Merge pull request 'Add offscreen render targets and rename AssetRegistry to ResourceRegistry' (#8) from dev into main

Reviewed-on: #8

.gitea/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,31 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ""
+labels: ""
+assignees: ""
+---
+
+**Desktop (please complete the following information):**
+
+- OS: [e.g. iOS]
+- Browser [e.g. chrome, safari]
+- Version [e.g. 22]
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+
+1. Something
+2. ...
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Additional context**
+Add any other context about the problem here.

.gitea/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,23 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ""
+labels: ""
+assignees: ""
+---
+
+Relates to:
+
+- TODO
+
+## Context
+
+TODO
+
+## Implementation
+
+TODO
+
+## Additional resources
+
+TODO

.gitea/pull_request_template.md

@@ -0,0 +1,18 @@
+resolves TODO
+
+## Context
+
+TODO
+
+## Implementation
+
+TODO
+
+## Screenshots
+
+TODO
+
+## Testing Instructions
+
+1. Build engine via `bin/dev build && cd build/ && make -j4`
+2. Run testbed via `./testbed`

.gitignore

@@ -24,7 +24,6 @@ CMakeUserPresets.json
 *.bin
 *.out
 *.spv
-*.spv.h
 
 # Runtime data
 pids

.vscode/settings.json

@@ -41,8 +41,8 @@
     "LD_LIBRARY_PATH": "/home/caleb/.local/share/vulkan-sdk/1.4.357.1/x86_64/lib/VulkanLoader/lib:/home/caleb/.local/share/vulkan-sdk/1.4.357.1/x86_64/lib",
     "VK_ADD_LAYER_PATH": "/home/caleb/.local/share/vulkan-sdk/1.4.357.1/x86_64/share/vulkan/explicit_layer.d"
   },
-  "cmake.buildDirectory": "${workspaceFolder}/build",
-  "cmake.generator": "Ninja",
+  "cmake.useCMakePresets": "always",
+  "cmake.copyCompileCommands": "${workspaceFolder}/build/compile_commands.json",
   "cmake.configureOnOpen": true,
   "files.associations": {
     ".clang-format": "yaml",

CLAUDE.md

@@ -0,0 +1,17 @@
+# Sophia
+
+## Dev helper (`bin/dev`)
+
+`bin/dev` wraps common project tasks. Run `bin/dev bash-completions` to list commands.
+
+### Creating issues
+
+Use `bin/dev issue` to create Gitea issues instead of calling the API or `tea` directly:
+
+```sh
+bin/dev issue "<title>" [-b "<body>"] [-l <label>]... [-a <user>]... [--open]
+```
+
+- Labels are repo label names (`bug`, `enhancement`, `question`, ...).
+- The Gitea API cannot add an issue to a project. After creating an issue, tell the user its URL so they can add it to the "sophia" project (issue sidebar > Projects), or pass `--open`.
+- Only create issues when the user asks; issues are visible on the remote.

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.22.2)
+cmake_minimum_required(VERSION 3.25.2)
 
 set(NAME sophia)
 
@@ -15,8 +15,6 @@ endif()
 
 if(CMAKE_BUILD_TYPE STREQUAL "Debug")
   message(STATUS "Debug build: enabling debug logging")
-else()
-  add_compile_definitions(NDEBUG)
 endif()
 
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)

CMakePresets.json

@@ -0,0 +1,66 @@
+{
+  "version": 6,
+  "configurePresets": [
+    {
+      "name": "base",
+      "hidden": true,
+      "generator": "Ninja",
+      "binaryDir": "${sourceDir}/build/${presetName}",
+      "cacheVariables": {
+        "CMAKE_EXPORT_COMPILE_COMMANDS": "ON"
+      }
+    },
+    {
+      "name": "debug",
+      "displayName": "Debug",
+      "inherits": "base",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Debug"
+      }
+    },
+    {
+      "name": "release",
+      "displayName": "Release (with debug info)",
+      "inherits": "base",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "RelWithDebInfo"
+      }
+    },
+    {
+      "name": "asan",
+      "displayName": "Debug + AddressSanitizer/UBSan",
+      "inherits": "debug",
+      "cacheVariables": {
+        "CMAKE_CXX_FLAGS": "-fsanitize=address,undefined -fno-omit-frame-pointer",
+        "CMAKE_C_FLAGS": "-fsanitize=address,undefined -fno-omit-frame-pointer"
+      }
+    },
+    {
+      "name": "tsan",
+      "displayName": "Debug + ThreadSanitizer",
+      "inherits": "debug",
+      "cacheVariables": {
+        "CMAKE_CXX_FLAGS": "-fsanitize=thread",
+        "CMAKE_C_FLAGS": "-fsanitize=thread"
+      }
+    }
+  ],
+  "buildPresets": [
+    {
+      "name": "debug",
+      "configurePreset": "debug"
+    },
+    {
+      "name": "release",
+      "configurePreset": "release"
+    },
+    {
+      "name": "asan",
+      "configurePreset": "asan"
+    },
+    {
+      "name": "tsan",
+      "configurePreset": "tsan"
+    }
+  ]
+}

README.md

@@ -8,17 +8,21 @@ COMING SOON
 
 ### Dependencies
 
-- [cmake](https://cmake.org/)
+- [cmake](https://cmake.org/) 3.25+
+- [Ninja](https://ninja-build.org/)
 - [Vulkan SDK](https://vulkan.lunarg.com/) - With validation layers
 
 ### Build instructions
 
+Builds use the presets in `CMakePresets.json` (`debug`, `release`), each in its own `build/<preset>` directory:
+
 ```sh
-cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
-cd build
-make -j
+cmake --preset debug
+cmake --build --preset debug
 ```
 
+Or with the dev helper: `dev build [preset] [--fresh]`.
+
 ## Third Party libraries used
 
 - [GLFW](https://github.com/glfw/glfw) - Window and input handling

bin/dev

@@ -19,6 +19,8 @@ WAIT_FOR_PROCESS = "wait_for_process"
 
 class DevHelper:
     SHADER_EXTENSIONS = (".vert", ".frag", ".comp", ".geom", ".tesc", ".tese")
+    PROJECT_NAME = "sophia"
+    DEFAULT_PRESET = "debug"
 
     def __init__(self):
         self.last_exit_status = 0
@@ -26,6 +28,9 @@ class DevHelper:
     # Core logic
     def call(self, *args, **kwargs):
         if not args:
+            print("Usage: dev <command> [args...]\n\nCommands:")
+            for command in self._commands():
+                print(f"  {command}")
             return
 
         command, rest = args[0], args[1:]
@@ -35,9 +40,29 @@ class DevHelper:
             return method(*rest, **kwargs)
 
     # Primary command wrappers
+
+    ##
+    # Configures and builds a CMake preset (see CMakePresets.json).
+    #   dev build [preset] [--fresh]
+    # The preset defaults to debug and builds into build/<preset>. --fresh
+    # discards the preset's CMake cache before configuring.
     def build(self, *args, **kwargs):
-        command = f"rm -rf build && cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug"
-        self._exec_in_root(command, replace=True)
+        preset, fresh = self._parse_preset_args(args, "build")
+        self._build_preset(preset, fresh)
+
+    ##
+    # Builds the debug preset (incrementally), then runs the testbed from
+    # build/debug. Any arguments are passed through to the testbed.
+    #   dev testbed [args...]
+    def testbed(self, *args, **kwargs):
+        preset = self.DEFAULT_PRESET
+        self._build_preset(preset, fresh=False)
+
+        preset_dir = os.path.join(self._project_root(), "build", preset)
+        binary = os.path.join(preset_dir, "bin", "testbed")
+        print(f"Running: {shlex.join([binary, *args])}")
+        os.chdir(preset_dir)
+        os.execv(binary, [binary, *args])
 
     ##
     # Checks out a branch named after a Gitea issue URL.
@@ -61,6 +86,40 @@ class DevHelper:
         flag = "" if exists else "-b "
         self._exec_in_root(f"git checkout {flag}{shlex.quote(branch_name)}", replace=True)
 
+    ##
+    # Creates an issue on this project's Gitea repo.
+    #   dev issue <title> [-b|--body <text>] [-l|--label <name>]... [-a|--assignee <user>]... [-o|--open]
+    # The body is read from stdin if --body is not given and stdin is piped.
+    # Gitea's API cannot add issues to a project (only the web UI can), so the
+    # issue URL is printed and --open opens it in the browser to do so.
+    def issue(self, *args, **kwargs):
+        title, body, labels, assignees, open_in_browser = self._parse_issue_args(args)
+
+        repo = self._origin_repo()
+        if repo is None:
+            raise RuntimeError("could not determine the Gitea repo from the origin remote")
+
+        payload = {"title": title, "body": body}
+        if labels:
+            label_ids = self._fetch_label_ids(repo)
+            unknown = [label for label in labels if label not in label_ids]
+            if unknown:
+                raise ValueError(f"Unknown label(s): {', '.join(unknown)} (available: {', '.join(sorted(label_ids))})")
+            payload["labels"] = [label_ids[label] for label in labels]
+        if assignees:
+            payload["assignees"] = assignees
+
+        issue = self._tea_api(f"repos/{repo}/issues", payload)
+        print(f"Created issue #{issue['number']}: {issue['title']}")
+        print(issue["html_url"])
+        print(f"Add it to the project from the issue sidebar: Projects > {self.PROJECT_NAME}")
+
+        if open_in_browser:
+            opener = shutil.which("xdg-open") or shutil.which("open")
+            if opener is None:
+                raise RuntimeError("xdg-open not found on PATH")
+            subprocess.Popen([opener, issue["html_url"]], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+
     def renderdoc(self, *args, **kwargs):
         qrenderdoc = self._find_qrenderdoc()
         self._exec_in_root(qrenderdoc, replace=True)
@@ -101,14 +160,62 @@ class DevHelper:
             raise NotImplementedError(f"Not implemented for platform {sys.platform}")
 
     def bash_completions(self, *args, **kwargs):
-        completions = sorted(
+        print(" ".join(self._commands()))
+
+    # Private helpers
+    def _commands(self):
+        return sorted(
             METHOD_TO_COMMAND.get(name, name)
             for name in vars(DevHelper)
             if not name.startswith("_") and name != "call" and callable(getattr(DevHelper, name))
         )
-        print(" ".join(completions))
 
-    # Private helpers
+    def _parse_preset_args(self, args, command):
+        preset = None
+        fresh = False
+        for arg in args:
+            if arg == "--fresh":
+                fresh = True
+            elif arg.startswith("-"):
+                raise ValueError(f"Unknown option: {arg}")
+            elif preset is None:
+                preset = arg
+            else:
+                raise ValueError(f"Usage: dev {command} [preset] [--fresh]")
+
+        preset = preset or self.DEFAULT_PRESET
+        presets = self._configure_presets()
+        if preset not in presets:
+            raise ValueError(f"Unknown preset: {preset} (available: {', '.join(presets)})")
+        return preset, fresh
+
+    def _configure_presets(self):
+        with open(os.path.join(self._project_root(), "CMakePresets.json")) as f:
+            presets = json.load(f)["configurePresets"]
+        return [preset["name"] for preset in presets if not preset.get("hidden")]
+
+    def _build_preset(self, preset, fresh):
+        configure = ["cmake", "--preset", preset]
+        if fresh:
+            configure.append("--fresh")
+        self._run_in_root(configure)
+        self._copy_compile_commands(preset)
+        self._run_in_root(["cmake", "--build", "--preset", preset])
+
+    # Editor tooling reads build/compile_commands.json, so point it at the
+    # most recently configured preset.
+    def _copy_compile_commands(self, preset):
+        build_dir = os.path.join(self._project_root(), "build")
+        source = os.path.join(build_dir, preset, "compile_commands.json")
+        if os.path.isfile(source):
+            shutil.copyfile(source, os.path.join(build_dir, "compile_commands.json"))
+
+    def _run_in_root(self, command):
+        print(f"Running: {shlex.join(command)}")
+        result = subprocess.run(command, cwd=self._project_root())
+        if result.returncode != 0:
+            sys.exit(result.returncode)
+
     def _parse_issue_url(self, url):
         match = re.match(r"^(https?://[^/]+)/([^/]+)/([^/]+)/issues/(\d+)", url)
         if match is None:
@@ -126,6 +233,63 @@ class DevHelper:
             raise RuntimeError(f"failed to fetch issue title from {endpoint}")
         return json.loads(result.stdout)["title"]
 
+    def _parse_issue_args(self, args):
+        title = None
+        body = None
+        labels = []
+        assignees = []
+        open_in_browser = False
+
+        args = list(args)
+        while args:
+            arg = args.pop(0)
+            if arg in ("-b", "--body", "-l", "--label", "-a", "--assignee"):
+                if not args:
+                    raise ValueError(f"{arg} requires a value")
+                value = args.pop(0)
+                if arg in ("-b", "--body"):
+                    body = value
+                elif arg in ("-l", "--label"):
+                    labels.append(value)
+                else:
+                    assignees.append(value)
+            elif arg in ("-o", "--open"):
+                open_in_browser = True
+            elif arg.startswith("-"):
+                raise ValueError(f"Unknown option: {arg}")
+            elif title is None:
+                title = arg
+            else:
+                title = f"{title} {arg}"
+
+        if not title:
+            raise ValueError("Must provide an issue title. Usage: dev issue <title> [-b <body>] [-l <label>]... [-a <user>]... [-o]")
+        if body is None:
+            body = "" if sys.stdin.isatty() else sys.stdin.read()
+        return title, body, labels, assignees, open_in_browser
+
+    def _tea_api(self, endpoint, payload=None):
+        if shutil.which("tea") is None:
+            raise RuntimeError("tea not found on PATH (install gitea tea and run `tea login add`)")
+
+        command = ["tea", "api", endpoint]
+        if payload is not None:
+            command += ["-d", "@-"]
+        print(f"Running: {' '.join(command)}")
+        result = subprocess.run(
+            command,
+            input=json.dumps(payload) if payload is not None else None,
+            stdout=subprocess.PIPE,
+            text=True,
+        )
+        if result.returncode != 0:
+            raise RuntimeError(f"tea api request failed: {endpoint}")
+        return json.loads(result.stdout)
+
+    def _fetch_label_ids(self, repo):
+        labels = self._tea_api(f"repos/{repo}/labels?limit=100")
+        return {label["name"]: label["id"] for label in labels}
+
     def _format_branch_name(self, issue_repo, issue_number, issue_title):
         formatted_title = re.sub(r"-+", "-", re.sub(r"[^a-z0-9\-]", "", re.sub(r"\s+", "-", issue_title.lower().strip())))
         if issue_repo == self._origin_repo():

docs/glossary.md

@@ -1,36 +1,56 @@
 # Glossary
 
-## AssetRegistry
+## ResourceRegistry
 
-An AssetRegistry owns GPU-backed assets on the caller's behalf and hands out
-lightweight Handles instead of pointers or ownership.
+A ResourceRegistry owns GPU-backed resources on the caller's behalf and hands out
+lightweight Handles instead of pointers or ownership. It is engine-internal:
+frontend code never sees it, and reaches it through a ResourceRegistryRef.
 
-Internally it's a collection of per-type pools, each responsible for one
-asset type:
+Internally it's a collection of per-type pools, each a `Pool<T, Handle>`
+(a generation-checked slot pool). A type that needs extra behaviour wraps its
+pool in a thin class instead:
 
 ```
-AssetRegistry
- ├── MeshPool     → MeshHandle
- ├── TexturePool  → TextureHandle   (planned)
- └── MaterialPool → MaterialHandle  (planned)
+ResourceRegistry
+ ├── meshPool          Pool<Mesh, MeshHandle>
+ ├── renderTargetPool  RenderTargetPool → RenderTargetHandle
+ │                     (wraps Pool; waits for the GPU on release, applies resizes)
+ ├── texturePool       (planned)
+ └── materialPool      (planned)
 ```
 
+Engine code (`Application`, `ImGuiRenderer`, `SceneRenderer`) uses the pools
+directly, e.g. `resources.renderTargetPool.get(handle)`.
+
 A Handle is a small (index, generation) pair. The index locates the slot in
 the pool; the generation is bumped when that slot is released, so a Handle
 kept around after release() is detected as stale instead of resolving to
-someone else's asset (or freed memory).
+someone else's resource (or freed memory).
+
+Think: "Where does the engine keep every GPU resource, and how does it look one
+up by handle?"
+
+## ResourceRegistryRef
+
+A ResourceRegistryRef is the frontend's non-owning, cheap-to-copy view of the
+ResourceRegistry, returned by `Application::resources()`. It exposes only what
+frontend code needs and hands out no pools, so no Vulkan-facing types leak
+through the public API:
+
+```
+create<T>(...)   load<T>(path)   release<T>(handle)
+requestResize(target, w, h)   getExtent(target)   isAlive(handle)
+```
 
 Typical lifecycle:
 
 ```
-load<Mesh>(path) / loadMesh(...)  →  MeshHandle
-                                        │
-                        get<Mesh>(handle)  →  const Mesh&
+load<Mesh>(path) / create<Mesh>(...)  →  MeshHandle
                                         │
                         release<Mesh>(handle)
 ```
 
-Think: "Where do I get or release a GPU asset by handle, without owning its
+Think: "How do I create or release a GPU resource by handle, without owning its
 lifetime directly?"
 
 ## Buffer
@@ -256,11 +276,13 @@ This is primarily a UI concept, rather than a GPU concept.
 A PanelRegistry owns Panels on the caller's behalf and hands out lightweight
 PanelHandles instead of pointers or ownership.
 
-Internally it's a generation-checked slot pool, the same shape AssetRegistry's
-per-type pools use:
+Internally it wraps a `Pool<Panel, PanelHandle>` (the same generation-checked
+slot pool ResourceRegistry uses, in `sophia/util/pool.hpp`) and adds the
+Panel-specific parts: lookup by type or name, and the default dock layout:
 
 ```
 PanelRegistry
+ └── Pool<Panel, PanelHandle>
       └── Slot { Panel, generation }  →  PanelHandle
 ```
 
@@ -279,6 +301,34 @@ Each frame, update(frameInfo) calls onUpdate on every visible Panel it holds.
 Think: "Where do I register or look up a UI panel by handle, without owning
 its lifetime directly?"
 
+## SceneRegistry
+
+A SceneRegistry owns Scenes on the caller's behalf and hands out lightweight
+SceneHandles instead of pointers or ownership. Like PanelRegistry, it is owned
+by Application and reached from frontend code directly (`scenes()`), rather than
+through ResourceRegistryRef: scenes are CPU-side entity data, not GPU resources.
+
+Internally it wraps a `Pool<Scene, SceneHandle>`:
+
+```
+SceneRegistry
+ └── Pool<Scene, SceneHandle>
+      └── Slot { Scene, generation }  →  SceneHandle
+```
+
+Typical lifecycle:
+
+```
+create()  →  SceneHandle
+                  │
+        get(handle)  →  Scene&
+                  │
+        release(handle)
+```
+
+Think: "Where do I create or look up a Scene by handle, without owning its
+lifetime directly?"
+
 ## Sprite
 
 A Sprite is a 2D renderable representation of an image, usually a rectangular region of a texture.

editor/main.cpp

@@ -18,7 +18,10 @@ class Editor : public sophia::Application {
     panels().emplace<SceneHierarchyPanel>();
     panels().emplace<InspectorPanel>();
     panels().emplace<AssetBrowserPanel>();
-    panels().emplace<ViewportPanel>();
+    sophia::RenderTargetHandle sceneTarget =
+        resources().create<sophia::RenderTarget>();
+    views().create({.scene = scenes().create(), .target = sceneTarget});
+    panels().emplace<ViewportPanel>(ui(), sceneTarget);
 
     panels().setDefaultLayout(
         {.left = {"Scene Hierarchy"},

editor/panels/viewport_panel.cpp

@@ -24,8 +24,9 @@ void ViewportPanel::onUpdate(const sophia::FrameInfo&) {
   const ImVec2 size = ImGui::GetContentRegionAvail();
   const ImVec2 end(origin.x + size.x, origin.y + size.y);
 
+  ui.image(target);
+
   ImDrawList* drawList = ImGui::GetWindowDrawList();
-  drawList->AddRectFilled(origin, end, IM_COL32(24, 26, 32, 255));
 
   if (showGrid) {
     constexpr float GRID_STEP = 40.0f;

editor/panels/viewport_panel.hpp

@@ -1,15 +1,25 @@
 #pragma once
 
 #include <sophia/frame_info.hpp>
+#include <sophia/handles.hpp>
 #include <sophia/ui/panel.hpp>
+#include <sophia/ui/ui.hpp>
 
 class ViewportPanel : public sophia::Panel {
  public:
-  ViewportPanel() : Panel{{.name = "Viewport"}} {}
+  ViewportPanel(sophia::UI& ui, sophia::RenderTargetHandle target)
+      : Panel{{.name = "Viewport",
+               .windowFlags = ImGuiWindowFlags_NoScrollbar |
+                              ImGuiWindowFlags_NoScrollWithMouse}},
+        ui{ui},
+        target{target} {}
 
   void onUpdate(const sophia::FrameInfo& frameInfo) override;
 
  private:
+  sophia::UI& ui;
+  sophia::RenderTargetHandle target;
+
   enum class GizmoMode { Move, Rotate, Scale };
 
   GizmoMode gizmoMode = GizmoMode::Move;

engine/CMakeLists.txt

@@ -17,6 +17,11 @@ target_include_directories(${ENGINE_NAME} PUBLIC
   "${CMAKE_CURRENT_SOURCE_DIR}/include"
 )
 
+target_compile_definitions(${ENGINE_NAME} PUBLIC
+  GLM_FORCE_RADIANS
+  GLM_FORCE_DEPTH_ZERO_TO_ONE
+)
+
 target_link_libraries(${ENGINE_NAME} PUBLIC
   vulkan
   shaderc

engine/include/sophia/application.hpp

@@ -3,21 +3,21 @@
 #include <cstdlib>
 #include <iostream>
 #include <memory>
-#include <sophia/asset_registry.hpp>
 #include <sophia/camera_2d.hpp>
 #include <sophia/canvas.hpp>
 #include <sophia/console/console_command_registry.hpp>
 #include <sophia/frame_info.hpp>
+#include <sophia/math.hpp>
+#include <sophia/resource_registry_ref.hpp>
+#include <sophia/scene_registry.hpp>
+#include <sophia/scene_view_registry.hpp>
 #include <sophia/types.hpp>
 #include <sophia/ui/debug_ui.hpp>
 #include <sophia/ui/panel_registry.hpp>
+#include <sophia/ui/ui.hpp>
 #include <string>
 #include <vector>
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-
 namespace sophia {
 
 class Application {
@@ -44,8 +44,11 @@ class Application {
   virtual void onRender() {}
   virtual void onDestroy() {}
 
-  AssetRegistry& assets() { return this->assetRegistry; }
+  ResourceRegistryRef resources();
   PanelRegistry& panels() { return this->panelRegistry; }
+  SceneRegistry& scenes() { return this->sceneRegistry; }
+  SceneViewRegistry& views() { return this->sceneViewRegistry; }
+  UI& ui() { return this->_ui; }
 
   DebugUI& debugUI() { return this->_debugUI; }
 
@@ -66,8 +69,10 @@ class Application {
   class Impl;
   std::unique_ptr<Impl> impl;
 
-  AssetRegistry assetRegistry;
   PanelRegistry panelRegistry;
+  SceneRegistry sceneRegistry;
+  SceneViewRegistry sceneViewRegistry;
+  UI _ui;
 
   DebugUI _debugUI;
 };

engine/include/sophia/asset_registry.hpp

@@ -1,64 +0,0 @@
-#pragma once
-
-#include <memory>
-#include <sophia/handles.hpp>
-#include <string>
-#include <vector>
-
-#include "sophia/canvas.hpp"
-#include "sophia/types.hpp"
-
-namespace sophia {
-
-class Device;
-class Mesh;
-
-template <typename T>
-struct AssetTraits;
-
-template <>
-struct AssetTraits<Mesh> {
-  using Handle = MeshHandle;
-};
-
-class AssetRegistry {
- public:
-  ~AssetRegistry();
-
-  AssetRegistry(const AssetRegistry&) = delete;
-  AssetRegistry& operator=(const AssetRegistry&) = delete;
-
-  template <typename T>
-  typename AssetTraits<T>::Handle load(const std::string& path);
-
-  /**
-   * TEMPORARY: Remove once load<Mesh> can read real model files from disk.
-   */
-  MeshHandle loadMesh(std::vector<CanvasVertex> vertices,
-                      std::vector<u32> indices);
-
-  template <typename T>
-  void release(typename AssetTraits<T>::Handle handle);
-
- private:
-  friend class Application;
-
-  explicit AssetRegistry(Device& device);
-
-  template <typename T>
-  const T& get(typename AssetTraits<T>::Handle handle) const;
-
-  class Impl;
-  std::unique_ptr<Impl> impl;
-};
-
-template <>
-MeshHandle AssetRegistry::load<Mesh>(const std::string& path);
-
-template <>
-void AssetRegistry::release<Mesh>(MeshHandle handle);
-
-template <>
-const Mesh& AssetRegistry::get<Mesh>(MeshHandle handle) const;
-
-}  // namespace sophia

engine/include/sophia/camera_2d.hpp

@@ -1,9 +1,7 @@
 #pragma once
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
+#include <sophia/math.hpp>
 
 namespace sophia {
 

engine/include/sophia/canvas.hpp

@@ -2,12 +2,9 @@
 
 #include <memory>
 #include <sophia/frame_info.hpp>
+#include <sophia/math.hpp>
 #include <vector>
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-
 namespace sophia {
 
 class Application;

engine/include/sophia/components.hpp

@@ -1,18 +1,17 @@
 #pragma once
 
-#include <sophia/asset_registry.hpp>
-#include <string>
-
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
-#include <glm/gtc/quaternion.hpp>
+#include <iostream>
+#include <ostream>
+#include <sophia/handles.hpp>
+#include <sophia/math.hpp>
+#include <string>
 
 namespace sophia {
 
 struct TagComponent {
   std::string tag;  // entt::hashed_string ?
+  uint32_t mask = 0;
 };
 
 struct TransformComponent {
@@ -28,10 +27,56 @@ struct TransformComponent {
   glm::mat3 normalMatrix() const {
     return glm::mat3{glm::transpose(glm::inverse(mat4()))};
   }
+
+  friend std::ostream& operator<<(std::ostream& os,
+                                  const TransformComponent& transform) {
+    os << "TransformComponent {\n"
+       << "  Position: (" << transform.position.x << ", "
+       << transform.position.y << ", " << transform.position.z << ")\n"
+       << "  Rotation (w, x, y, z): (" << transform.rotation.w << ", "
+       << transform.rotation.x << ", " << transform.rotation.y << ", "
+       << transform.rotation.z << ")\n"
+       << "  Scale: (" << transform.scale.x << ", " << transform.scale.y << ", "
+       << transform.scale.z << ")\n"
+       << "}";
+    return os;
+  }
 };
 
 struct MeshComponent {
   MeshHandle handle;
 };
 
+struct CameraComponent {
+  struct Orthographic {
+    float height = 10.f;
+    float nearPlane = -1.f;
+    float farPlane = 1.f;
+  };
+
+  struct Perspective {
+    float fov = glm::radians(60.f);
+    float nearPlane = 0.1f;
+    float farPlane = 100.f;
+  };
+
+  enum class Projection { Orthographic, Perspective };
+
+  Projection projection = Projection::Orthographic;
+  Orthographic ortho;
+  Perspective perspective;
+
+  glm::mat4 getProjection(float aspect) const {
+    if (projection == Projection::Perspective) {
+      return glm::perspective(perspective.fov, aspect, perspective.nearPlane,
+                              perspective.farPlane);
+    }
+
+    float halfHeight = ortho.height / 2.f;
+    float halfWidth = halfHeight * aspect;
+    return glm::ortho(-halfWidth, halfWidth, -halfHeight, halfHeight,
+                      ortho.nearPlane, ortho.farPlane);
+  }
+};
+
 }  // namespace sophia

engine/include/sophia/entity.hpp

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <entt/entt.hpp>
+#include <sophia/scene.hpp>
+#include <sophia/types.hpp>
+#include <sophia/util/assert.hpp>
+
+namespace sophia {
+
+class Entity {
+ public:
+  Entity(const Entity&) = default;
+  Entity& operator=(const Entity&) = default;
+
+  Entity() = default;
+  Entity(entt::entity handle, Scene* scene);
+
+  template <typename T, typename... Args>
+  T& addComponent(Args&&... args) {
+    SOPHIA_ASSERT(!hasComponent<T>(), "Entity already has component!");
+    T& component =
+        scene->registry.emplace<T>(handle, std::forward<Args>(args)...);
+    // scene->OnComponentAdded<T>(*this, component);
+    return component;
+  }
+
+  template <typename T>
+  T& getComponent() {
+    SOPHIA_ASSERT(hasComponent<T>(), "Entity does not have component!");
+    return scene->registry.get<T>(handle);
+  }
+
+  template <typename T>
+  bool hasComponent() {
+    return scene->registry.all_of<T>(handle);
+  }
+
+  template <typename T>
+  void removeComponent() {
+    SOPHIA_ASSERT(hasComponent<T>(), "Entity does not have component!");
+    scene->registry.remove<T>(handle);
+  }
+
+  operator bool() const { return handle != entt::null; }
+  operator entt::entity() const { return handle; }
+  operator u32() const { return (u32)handle; }
+
+  // UUID GetUUID() { return GetComponent<IDComponent>().ID; }
+  // const std::string& GetName() { return GetComponent<TagComponent>().Tag; }
+
+  bool operator==(const Entity& other) const {
+    return handle == other.handle && scene == other.scene;
+  }
+
+  bool operator!=(const Entity& other) const { return !(*this == other); }
+
+ private:
+  entt::entity handle{entt::null};
+  Scene* scene = nullptr;
+};
+
+}  // namespace sophia

engine/include/sophia/frame_info.hpp

@@ -1,12 +1,9 @@
 #pragma once
 
 #include <sophia/camera_2d.hpp>
+#include <sophia/math.hpp>
 #include <sophia/types.hpp>
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-
 namespace sophia {
 
 struct FrameInfo {

engine/include/sophia/handles.hpp

@@ -6,7 +6,7 @@
 
 namespace sophia {
 
-template <typename Tag>
+template <typename T>
 struct Handle {
   static constexpr u32 INVALID_INDEX = (1u << 20) - 1;
 
@@ -24,10 +24,25 @@ struct Handle {
   [[nodiscard]] auto operator<=>(const Handle&) const = default;
 };
 
-struct MeshTag {};
-struct PanelTag {};
+struct InvalidHandle {
+  template <typename T>
+  [[nodiscard]] constexpr operator Handle<T>() const {
+    return Handle<T>::invalid();
+  }
+};
 
-using MeshHandle = Handle<MeshTag>;
-using PanelHandle = Handle<PanelTag>;
+inline constexpr InvalidHandle INVALID_HANDLE{};
+
+class Mesh;
+class Panel;
+class RenderTarget;
+class Scene;
+struct SceneView;
+
+using MeshHandle = Handle<Mesh>;
+using PanelHandle = Handle<Panel>;
+using RenderTargetHandle = Handle<RenderTarget>;
+using SceneHandle = Handle<Scene>;
+using SceneViewHandle = Handle<SceneView>;
 
 }  // namespace sophia

engine/include/sophia/math.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <glm/glm.hpp>
+#include <glm/gtc/quaternion.hpp>
+
+namespace sophia {
+
+using vec2 = glm::vec2;
+using vec3 = glm::vec3;
+using vec4 = glm::vec4;
+using ivec2 = glm::ivec2;
+using uvec2 = glm::uvec2;
+using mat3 = glm::mat3;
+using mat4 = glm::mat4;
+using quat = glm::quat;
+
+}  // namespace sophia

engine/include/sophia/resource_registry_ref.hpp

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <sophia/canvas.hpp>
+#include <sophia/handles.hpp>
+#include <sophia/math.hpp>
+#include <sophia/types.hpp>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+namespace sophia {
+
+class ResourceRegistry;
+
+class ResourceRegistryRef {
+ public:
+  template <typename T>
+  Handle<T> load(const std::string& path);
+
+  template <typename T, typename... Args>
+  Handle<T> create(Args&&... args) {
+    return createResource(std::type_identity<T>{}, std::forward<Args>(args)...);
+  }
+
+  void requestResize(RenderTargetHandle handle, u32 width, u32 height);
+
+  glm::vec2 getExtent(RenderTargetHandle handle) const;
+
+  bool isAlive(RenderTargetHandle handle) const;
+
+  template <typename T>
+  void release(Handle<T> handle);
+
+ private:
+  friend class Application;
+
+  explicit ResourceRegistryRef(ResourceRegistry& registry)
+      : registry{&registry} {}
+
+  MeshHandle createResource(std::type_identity<Mesh>,
+                            std::vector<CanvasVertex> vertices,
+                            std::vector<u32> indices = {});
+
+  RenderTargetHandle createResource(std::type_identity<RenderTarget>,
+                                    u32 width = 1, u32 height = 1);
+
+  ResourceRegistry* registry;
+};
+
+template <>
+MeshHandle ResourceRegistryRef::load<Mesh>(const std::string& path);
+
+template <>
+void ResourceRegistryRef::release<Mesh>(MeshHandle handle);
+
+template <>
+void ResourceRegistryRef::release<RenderTarget>(RenderTargetHandle handle);
+
+}  // namespace sophia

engine/include/sophia/scene.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <entt/entt.hpp>
+#include <string>
+
+namespace sophia {
+
+class Entity;
+class SceneRenderer;  // !TEMP remove this
+
+class Scene {
+ public:
+  Scene();
+  ~Scene();
+
+  void createEntity(const std::string& name = {});
+  void destroyEntity(Entity entity);
+
+  // The camera a render request uses when it doesn't name one. Null until
+  // set.
+  entt::entity getActiveCamera() const { return activeCamera; }
+  void setActiveCamera(entt::entity camera) { activeCamera = camera; }
+
+ private:
+  friend class Entity;
+  friend class SceneRenderer;  // !TEMP remove this
+
+  entt::registry registry;
+  entt::entity activeCamera = entt::null;
+};
+
+}  // namespace sophia

engine/include/sophia/scene_registry.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <sophia/handles.hpp>
+#include <sophia/scene.hpp>
+#include <sophia/util/pool.hpp>
+
+namespace sophia {
+
+class SceneRegistry {
+ public:
+  SceneRegistry(const SceneRegistry&) = delete;
+  SceneRegistry& operator=(const SceneRegistry&) = delete;
+
+  SceneRegistry() = default;
+  ~SceneRegistry() = default;
+
+  SceneHandle create() { return pool.create(); }
+
+  const Scene& get(SceneHandle handle) const { return pool.get(handle); }
+  Scene& get(SceneHandle handle) { return pool.get(handle); }
+
+  void release(SceneHandle handle) { pool.release(handle); }
+  bool isAlive(SceneHandle handle) const { return pool.isAlive(handle); }
+
+  u32 size() const { return pool.size(); }
+
+ private:
+  Pool<Scene> pool{"Scene"};
+};
+
+}  // namespace sophia

engine/include/sophia/scene_view.hpp

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <sophia/entity.hpp>
+#include <sophia/handles.hpp>
+#include <sophia/math.hpp>
+#include <sophia/scene.hpp>
+
+namespace sophia {
+
+enum class ClearFlags : u8 {
+  None = 0,
+  Color = 1 << 0,
+  Depth = 1 << 1,
+  Stencil = 1 << 2,
+  All = Color | Depth | Stencil
+};
+
+struct SceneView {
+  SceneHandle scene = INVALID_HANDLE;
+  RenderTargetHandle target = INVALID_HANDLE;
+  Entity camera;
+
+  vec4 viewport{0.0f, 0.0f, 1.0f, 1.0f};
+
+  vec4 clearColor{0.f, 0.f, 0.f, 1.f};
+  ClearFlags clearFlags = ClearFlags::All;
+
+  u32 priority = 0;  // Lower priority renders first
+  u32 layerMask = 0xFFFFFFFF;
+
+  bool enabled = true;  // Disabled views are kept but not rendered
+};
+
+}  // namespace sophia

engine/include/sophia/scene_view_registry.hpp

@@ -0,0 +1,86 @@
+#pragma once
+
+#include <algorithm>
+#include <sophia/handles.hpp>
+#include <sophia/scene_view.hpp>
+#include <sophia/util/pool.hpp>
+#include <utility>
+#include <vector>
+
+namespace sophia {
+
+/**
+ * Every live SceneView. The application renders all enabled views each frame,
+ * in ascending priority order, before the UI.
+ */
+class SceneViewRegistry {
+ public:
+  SceneViewRegistry(const SceneViewRegistry&) = delete;
+  SceneViewRegistry& operator=(const SceneViewRegistry&) = delete;
+
+  SceneViewRegistry() = default;
+  ~SceneViewRegistry() = default;
+
+  SceneViewHandle create(const SceneView& view = {}) {
+    isRenderQueueDirty = true;
+    return pool.create(view);
+  }
+
+  const SceneView& get(SceneViewHandle handle) const {
+    return pool.get(handle);
+  }
+
+  SceneView& get(SceneViewHandle handle) {
+    isRenderQueueDirty = true;
+    return pool.get(handle);
+  }
+
+  void release(SceneViewHandle handle) {
+    isRenderQueueDirty = true;
+    pool.release(handle);
+  }
+
+  bool isAlive(SceneViewHandle handle) const { return pool.isAlive(handle); }
+
+  u32 size() const { return pool.size(); }
+
+  template <typename Fn>
+  void forEach(Fn&& fn) {
+    isRenderQueueDirty = true;
+    pool.forEach(std::forward<Fn>(fn));
+  }
+
+  template <typename Fn>
+  void forEach(Fn&& fn) const {
+    pool.forEach(std::forward<Fn>(fn));
+  }
+
+  const std::vector<SceneViewHandle>& GetRenderQueue() const {
+    if (isRenderQueueDirty) {
+      rebuildRenderQueue();
+    }
+    return renderQueue;
+  }
+
+ private:
+  void rebuildRenderQueue() const {
+    renderQueue.clear();
+    pool.forEachWithHandle([&](SceneViewHandle handle, const SceneView& view) {
+      if (view.enabled) {
+        renderQueue.push_back(handle);
+      }
+    });
+
+    std::ranges::stable_sort(renderQueue, {}, [this](SceneViewHandle handle) {
+      return pool.get(handle).priority;
+    });
+    isRenderQueueDirty = false;
+  }
+
+  Pool<SceneView> pool{"SceneView"};
+
+  mutable std::vector<SceneViewHandle> renderQueue;
+  mutable bool isRenderQueueDirty = true;
+};
+
+}  // namespace sophia

engine/include/sophia/ui/debug_ui.hpp

@@ -17,9 +17,9 @@ class DebugUI {
   void show();
   void hide();
 
-  void showPanelRegistry(bool show = true);
-  void showFrameStats(bool show = true);
-  void showConsole(bool show = true);
+  void showPanelRegistry(bool show = false);
+  void showFrameStats(bool show = false);
+  void showConsole(bool show = false);
 
  private:
   PanelRegistry& registry;

engine/include/sophia/ui/panel_registry.hpp

@@ -6,6 +6,7 @@
 #include <sophia/ui/dock_layout.hpp>
 #include <sophia/ui/panel.hpp>
 #include <sophia/util/assert.hpp>
+#include <sophia/util/pool.hpp>
 #include <string_view>
 #include <typeinfo>
 #include <utility>
@@ -21,17 +22,17 @@ class PanelRegistry {
   PanelRegistry() = default;
   ~PanelRegistry() = default;
 
-  PanelHandle add(std::unique_ptr<Panel> panel);
+  PanelHandle add(std::unique_ptr<Panel> panel) {
+    return pool.add(std::move(panel));
+  }
 
   template <typename T, typename... Args>
   PanelHandle emplace(Args&&... args) {
     return add(std::make_unique<T>(std::forward<Args>(args)...));
   }
 
-  const Panel& get(PanelHandle handle) const;
-  Panel& get(PanelHandle handle) {
-    return const_cast<Panel&>(std::as_const(*this).get(handle));
-  }
+  const Panel& get(PanelHandle handle) const { return pool.get(handle); }
+  Panel& get(PanelHandle handle) { return pool.get(handle); }
 
   template <typename T>
   const T& get(PanelHandle handle) const {
@@ -46,19 +47,17 @@ class PanelRegistry {
     return const_cast<T&>(std::as_const(*this).template get<T>(handle));
   }
 
-  void remove(PanelHandle handle);
-  bool isValid(PanelHandle handle) const;
+  void remove(PanelHandle handle) { pool.release(handle); }
+  bool isValid(PanelHandle handle) const { return pool.isAlive(handle); }
 
   template <typename T>
   const T* find() const {
-    for (const Slot& slot : slots) {
-      if (slot.panel) {
-        if (const T* panel = dynamic_cast<const T*>(slot.panel.get())) {
-          return panel;
-        }
-      }
-    }
-    return nullptr;
+    const T* result = nullptr;
+    pool.findIf([&result](const Panel& panel) {
+      result = dynamic_cast<const T*>(&panel);
+      return result != nullptr;
+    });
+    return result;
   }
 
   template <typename T>
@@ -67,29 +66,22 @@ class PanelRegistry {
   }
 
   const Panel* find(std::string_view name) const {
-    for (const Slot& slot : slots) {
-      if (slot.panel && slot.panel->getName() == name) {
-        return slot.panel.get();
-      }
-    }
-    return nullptr;
+    return pool.findIf(
+        [name](const Panel& panel) { return panel.getName() == name; });
   }
 
   Panel* find(std::string_view name) {
     return const_cast<Panel*>(std::as_const(*this).find(name));
   }
 
-  u32 size() const;
+  u32 size() const { return pool.size(); }
   u32 visibleCount() const;
 
   std::vector<std::string_view> names() const {
     std::vector<std::string_view> result;
-    result.reserve(slots.size());
-    for (const Slot& slot : slots) {
-      if (slot.panel) {
-        result.push_back(slot.panel->getName());
-      }
-    }
+    result.reserve(pool.size());
+    pool.forEach(
+        [&result](const Panel& panel) { result.push_back(panel.getName()); });
     return result;
   }
 
@@ -101,13 +93,7 @@ class PanelRegistry {
   const DockLayout& getDefaultLayout() const { return defaultLayout; }
 
  private:
-  struct Slot {
-    std::unique_ptr<Panel> panel;
-    u32 generation = 0;
-  };
-
-  std::vector<Slot> slots;
-  std::vector<u32> freeList;
+  Pool<Panel> pool{"Panel"};
   DockLayout defaultLayout;
 };
 

engine/include/sophia/ui/ui.hpp

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <imgui.h>
+
+#include <sophia/handles.hpp>
+#include <sophia/resource_registry_ref.hpp>
+
+namespace sophia {
+
+class ImGuiRenderer;
+
+class UI {
+ public:
+  UI(const UI&) = delete;
+  UI& operator=(const UI&) = delete;
+
+  /**
+   * Draws the target filling the space left in the current window, and keeps
+   * the target sized to match. The target catches up on the next frame, so the
+   * image may be a frame behind while the window is being resized.
+   */
+  void image(RenderTargetHandle handle);
+
+  /**
+   * Texture to hand to ImGui::Image() that shows the target's contents.
+   * Changes when the target is resized, so fetch it each frame rather than
+   * caching it.
+   */
+  ImTextureID getTextureId(RenderTargetHandle handle);
+
+ private:
+  friend class Application;
+
+  explicit UI(ResourceRegistryRef resources) : resources{resources} {}
+
+  ResourceRegistryRef resources;
+  ImGuiRenderer* renderer = nullptr;
+};
+
+}  // namespace sophia

engine/include/sophia/util/pool.hpp

@@ -0,0 +1,131 @@
+#pragma once
+
+#include <memory>
+#include <sophia/handles.hpp>
+#include <sophia/types.hpp>
+#include <sophia/util/assert.hpp>
+#include <utility>
+#include <vector>
+
+namespace sophia {
+
+template <typename T>
+class Pool {
+ public:
+  explicit Pool(const char* name) : name{name} {}
+
+  Pool(const Pool&) = delete;
+  Pool& operator=(const Pool&) = delete;
+
+  template <typename... Args>
+  Handle<T> create(Args&&... args) {
+    return add(std::make_unique<T>(std::forward<Args>(args)...));
+  }
+
+  Handle<T> add(std::unique_ptr<T> item) {
+    if (!freeList.empty()) {
+      u32 index = freeList.back();
+      freeList.pop_back();
+      slots[index].item = std::move(item);
+      return Handle<T>{index, slots[index].generation};
+    }
+
+    slots.push_back(Slot{std::move(item), 0});
+    return Handle<T>{static_cast<u32>(slots.size() - 1), 0};
+  }
+
+  T& get(Handle<T> handle) {
+    return const_cast<T&>(std::as_const(*this).get(handle));
+  }
+
+  const T& get(Handle<T> handle) const { return *validate(handle).item; }
+
+  void release(Handle<T> handle) {
+    validate(handle);
+
+    Slot& slot = slots[handle.index];
+    slot.item.reset();
+    slot.generation = (slot.generation + 1) & GENERATION_MASK;
+    freeList.push_back(handle.index);
+  }
+
+  bool isAlive(Handle<T> handle) const {
+    return handle.isValid() && handle.index < slots.size() &&
+           slots[handle.index].generation == handle.generation &&
+           slots[handle.index].item != nullptr;
+  }
+
+  u32 size() const { return static_cast<u32>(slots.size() - freeList.size()); }
+
+  template <typename Fn>
+  void forEach(Fn&& fn) {
+    for (Slot& slot : slots) {
+      if (slot.item) {
+        fn(*slot.item);
+      }
+    }
+  }
+
+  template <typename Fn>
+  void forEach(Fn&& fn) const {
+    for (const Slot& slot : slots) {
+      if (slot.item) {
+        fn(*slot.item);
+      }
+    }
+  }
+
+  /** Calls `fn(handle, item)` for every live item. */
+  template <typename Fn>
+  void forEachWithHandle(Fn&& fn) const {
+    for (u32 index = 0; index < slots.size(); index++) {
+      const Slot& slot = slots[index];
+      if (slot.item) {
+        fn(Handle<T>{index, slot.generation}, *slot.item);
+      }
+    }
+  }
+
+  template <typename Predicate>
+  T* findIf(Predicate&& predicate) {
+    return const_cast<T*>(
+        std::as_const(*this).findIf(std::forward<Predicate>(predicate)));
+  }
+
+  template <typename Predicate>
+  const T* findIf(Predicate&& predicate) const {
+    for (const Slot& slot : slots) {
+      if (slot.item && predicate(*slot.item)) {
+        return slot.item.get();
+      }
+    }
+    return nullptr;
+  }
+
+ private:
+  static constexpr u32 GENERATION_MASK = (1u << 12) - 1;
+
+  struct Slot {
+    std::unique_ptr<T> item;
+    u32 generation = 0;
+  };
+
+  const Slot& validate(Handle<T> handle) const {
+    SOPHIA_ASSERT(handle.isValid(), "invalid handle:", name);
+    SOPHIA_ASSERT(handle.index < slots.size(), name,
+                  "handle index out of range:", handle.index);
+
+    const Slot& slot = slots[handle.index];
+    SOPHIA_ASSERT(slot.generation == handle.generation, "stale", name,
+                  "handle (generation mismatch):", handle.index);
+    SOPHIA_ASSERT(slot.item != nullptr, name,
+                  "handle refers to a released item:", handle.index);
+    return slot;
+  }
+
+  const char* name;
+  std::vector<Slot> slots;
+  std::vector<u32> freeList;
+};
+
+}  // namespace sophia

engine/src/application.cpp

@@ -1,6 +1,11 @@
+#include <imgui.h>
+
+#include <algorithm>
 #include <array>
 #include <chrono>
 #include <cstddef>
+#include <glm/glm.hpp>
+#include <map>
 #include <sophia/application.hpp>
 #include <sophia/util/logger.hpp>
 #include <string>
@@ -8,20 +13,18 @@
 #include <vector>
 #include <vulkan/vulkan.hpp>
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <imgui.h>
-
-#include <glm/glm.hpp>
-
-#include "buffer.hpp"
-#include "device.hpp"
-#include "imgui_renderer.hpp"
-#include "mesh.hpp"
-#include "pipelines/graphics_pipeline.hpp"
-#include "render_context.hpp"
-#include "shader.hpp"
-#include "systems/model_render_system.hpp"
+#include "rendering/imgui_renderer.hpp"
+#include "rendering/model_render_system.hpp"
+#include "rendering/render_context.hpp"
+#include "rendering/render_graph.hpp"
+#include "rendering/scene_renderer.hpp"
+#include "resources/mesh.hpp"
+#include "resources/render_target.hpp"
+#include "resources/resource_registry.hpp"
+#include "vulkan/buffer.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/pipelines/graphics_pipeline.hpp"
+#include "vulkan/shader.hpp"
 #include "window.hpp"
 
 namespace sophia {
@@ -41,6 +44,12 @@ struct PushConstants {
 
 std::vector<std::string> commandLineArgs;
 
+constexpr ClearColor CLEAR_COLOR = {0.01f, 0.01f, 0.02f, 1.0f};
+
+bool hasFlag(ClearFlags flags, ClearFlags flag) {
+  return (static_cast<u8>(flags) & static_cast<u8>(flag)) != 0;
+}
+
 }  // namespace
 
 class Application::Impl {
@@ -50,12 +59,17 @@ class Application::Impl {
         config{config},
         window{config.width, config.height, config.name},
         device{&window},
-        renderContext{window, device} {}
+        renderContext{window, device},
+        resourceRegistry{device, renderContext.getImageFormat()} {}
 
   void run() {
     ModelRenderSystem modelRenderSystem{device, renderContext};
+    SceneRenderer sceneRenderer{this->application.sceneRegistry,
+                                this->resourceRegistry};
     ImGuiRenderer imguiRenderer{window, device, renderContext.getImageFormat(),
-                                renderContext.getImageCount()};
+                                renderContext.getImageCount(),
+                                this->resourceRegistry};
+    this->application._ui.renderer = &imguiRenderer;
 
     this->application.consoleCommandRegistry.registerCommand(
         "reset_layout", "Restore the default panel layout",
@@ -65,8 +79,17 @@ class Application::Impl {
         });
 
     this->application.onCreate();
-    imguiRenderer.setDefaultLayout(
-        this->application.panelRegistry.getDefaultLayout());
+
+    auto& meshPool = this->resourceRegistry.meshPool;
+    auto& renderTargetPool = this->resourceRegistry.renderTargetPool;
+
+    PanelRegistry& panelRegistry = this->application.panelRegistry;
+    SceneRegistry& sceneRegistry = this->application.sceneRegistry;
+    SceneViewRegistry& sceneViewRegistry = this->application.sceneViewRegistry;
+    const SceneViewRegistry& sceneViewRegistryConst =
+        this->application.sceneViewRegistry;
+
+    imguiRenderer.setDefaultLayout(panelRegistry.getDefaultLayout());
 
     auto startTime = std::chrono::high_resolution_clock::now();
     auto currentTime = startTime;
@@ -83,6 +106,10 @@ class Application::Impl {
       double elapsedTime =
           std::chrono::duration<double>(currentTime - startTime).count();
 
+      // Resizing waits for the GPU, so it has to happen before any of this
+      // frame's work (or ImGui's references to the targets) is recorded.
+      renderTargetPool.applyPendingResizes();
+
       vk::Extent2D extent = renderContext.getExtent();
       FrameInfo frameInfo{frameIndex, elapsedTime, deltaTime,
                           glm::vec2(static_cast<float>(extent.width),
@@ -102,41 +129,9 @@ class Application::Impl {
 
       imguiRenderer.beginFrame();
 
-      this->application.panelRegistry.update(frameInfo);
+      panelRegistry.update(frameInfo);
       this->application.onRender();
 
-      renderContext.transitionCurrentImage(
-          commandBuffer, vk::ImageLayout::eColorAttachmentOptimal);
-
-      vk::ClearValue clearValue{};
-      clearValue.color =
-          vk::ClearColorValue{std::array<float, 4>{0.01f, 0.01f, 0.02f, 1.0f}};
-
-      vk::RenderingAttachmentInfo colorAttachment{};
-      colorAttachment.imageView = renderContext.getCurrentImageView();
-      colorAttachment.imageLayout = vk::ImageLayout::eColorAttachmentOptimal;
-      colorAttachment.loadOp = vk::AttachmentLoadOp::eClear;
-      colorAttachment.storeOp = vk::AttachmentStoreOp::eStore;
-      colorAttachment.clearValue = clearValue;
-
-      vk::RenderingInfo renderingInfo{};
-      renderingInfo.renderArea = vk::Rect2D{{0, 0}, extent};
-      renderingInfo.layerCount = 1;
-      renderingInfo.colorAttachmentCount = 1;
-      renderingInfo.pColorAttachments = &colorAttachment;
-
-      commandBuffer.beginRendering(renderingInfo);
-
-      vk::Viewport viewport{0.0f,
-                            0.0f,
-                            static_cast<float>(extent.width),
-                            static_cast<float>(extent.height),
-                            0.0f,
-                            1.0f};
-      vk::Rect2D scissor{{0, 0}, extent};
-      commandBuffer.setViewport(0, viewport);
-      commandBuffer.setScissor(0, scissor);
-
       std::vector<ModelRenderSystem::MeshInstance> instances;
       instances.reserve(this->meshes.size() + this->drawCalls.size());
       for (const std::unique_ptr<Mesh>& mesh : this->meshes) {
@@ -144,16 +139,61 @@ class Application::Impl {
       }
       instances.insert(instances.end(), this->drawCalls.begin(),
                        this->drawCalls.end());
-
-      modelRenderSystem.render(commandBuffer, instances, frameInfo);
       this->drawCalls.clear();
 
+      RenderGraph graph;
+      ImageRef backbuffer =
+          graph.importImage(renderContext.getCurrentImage(), Access::Present);
+
+      std::map<RenderTargetHandle, ImageRef> viewTargets;
+      for (SceneViewHandle handle : sceneViewRegistryConst.GetRenderQueue()) {
+        const SceneView& view = sceneViewRegistryConst.get(handle);
+        if (!sceneRegistry.isAlive(view.scene) ||
+            !renderTargetPool.isAlive(view.target)) {
+          continue;
+        }
+
+        auto [it, inserted] = viewTargets.try_emplace(view.target);
+        if (inserted) {
+          it->second =
+              graph.importImage(renderTargetPool.get(view.target).getImage(),
+                                Access::SampledRead);
+        }
+
+        const vec4& color = view.clearColor;
+        graph.addPass(
+            "scene view",
+            [&](RenderGraph::PassBuilder& pass) {
+              pass.writeColor(it->second,
+                              hasFlag(view.clearFlags, ClearFlags::Color)
+                                  ? vk::AttachmentLoadOp::eClear
+                                  : vk::AttachmentLoadOp::eLoad,
+                              {color.r, color.g, color.b, color.a});
+            },
+            [&sceneRenderer, &sceneViewRegistry, handle](vk::CommandBuffer) {
+              const SceneView& view = sceneViewRegistry.get(handle);
+              if (view.camera) {
+                sceneRenderer.render(view);
+              }
+            });
+      }
+
+      graph.addPass(
+          "main",
+          [&](RenderGraph::PassBuilder& pass) {
+            pass.writeColor(backbuffer, vk::AttachmentLoadOp::eClear,
+                            CLEAR_COLOR);
+            for (const auto& [handle, target] : viewTargets) {
+              pass.sample(target);
+            }
+          },
+          [&](vk::CommandBuffer commandBuffer) {
+            modelRenderSystem.render(commandBuffer, instances, frameInfo);
+
             imguiRenderer.endFrame(commandBuffer);
+          });
 
-      commandBuffer.endRendering();
-
-      renderContext.transitionCurrentImage(commandBuffer,
-                                           vk::ImageLayout::ePresentSrcKHR);
+      graph.execute(commandBuffer);
 
       renderContext.endFrame();
 
@@ -164,6 +204,8 @@ class Application::Impl {
 
     device.waitIdle();
 
+    this->application._ui.renderer = nullptr;
+
     auto endTime = std::chrono::high_resolution_clock::now();
     double totalRuntime =
         std::chrono::duration<double>(endTime - startTime).count();
@@ -193,7 +235,7 @@ class Application::Impl {
     this->drawCalls.push_back({&mesh, transform});
   }
 
-  Device& getDevice() { return device; }
+  ResourceRegistry& getResourceRegistry() { return resourceRegistry; }
 
  private:
   Application& application;
@@ -201,6 +243,7 @@ class Application::Impl {
   Window window;
   Device device;
   RenderContext renderContext;
+  ResourceRegistry resourceRegistry;
 
   std::vector<std::unique_ptr<Mesh>> meshes;
   std::vector<ModelRenderSystem::MeshInstance> drawCalls;
@@ -214,13 +257,17 @@ Application::Application(const Config& config)
     : impl{std::make_unique<Impl>(*this, config)},
       canvas{this},
       args{std::move(commandLineArgs)},
-      assetRegistry{impl->getDevice()},
+      _ui{ResourceRegistryRef{impl->getResourceRegistry()}},
       _debugUI{this->panelRegistry, this->consoleCommandRegistry} {}
 
 Application::~Application() = default;
 
 void Application::run() { impl->run(); }
 
+ResourceRegistryRef Application::resources() {
+  return ResourceRegistryRef{impl->getResourceRegistry()};
+}
+
 void Application::pushMesh(std::vector<CanvasVertex> vertices,
                            std::vector<u32> indices) {
   impl->pushMesh(std::move(vertices), std::move(indices));
@@ -229,7 +276,7 @@ void Application::pushMesh(std::vector<CanvasVertex> vertices,
 void Application::clearMeshes() { impl->clearMeshes(); }
 
 void Application::drawMesh(MeshHandle handle, const glm::mat4& transform) {
-  impl->drawMesh(assetRegistry.get<Mesh>(handle), transform);
+  impl->drawMesh(impl->getResourceRegistry().meshPool.get(handle), transform);
 }
 
 }  // namespace sophia

engine/src/assets/asset_registry.cpp

@@ -1,60 +0,0 @@
-#include <sophia/asset_registry.hpp>
-#include <sophia/util/assert.hpp>
-
-#include "mesh.hpp"
-#include "pools/mesh_pool.hpp"
-
-namespace sophia {
-
-class AssetRegistry::Impl {
- public:
-  explicit Impl(Device& device) : meshPool{device} {}
-
-  MeshPool meshPool;
-  // TexturePool texturePool;
-  // MaterialPool materialPool;
-};
-
-AssetRegistry::AssetRegistry(Device& device)
-    : impl{std::make_unique<Impl>(device)} {}
-
-AssetRegistry::~AssetRegistry() = default;
-
-template <>
-MeshHandle AssetRegistry::load<Mesh>(const std::string& path) {
-  (void)path;
-  SOPHIA_ASSERT(false,
-                "Mesh::load(path) is not implemented yet - no model file "
-                "format is supported; build one via Mesh::Builder for now");
-  return MeshHandle{};
-}
-
-template <typename T>
-typename AssetTraits<T>::Handle load(const std::string&) {
-  static_assert(sizeof(T) == 0,
-                "load<T> is not implemented for this asset type");
-}
-
-template <>
-void AssetRegistry::release<Mesh>(MeshHandle handle) {
-  impl->meshPool.release(handle);
-}
-
-template <>
-const Mesh& AssetRegistry::get<Mesh>(MeshHandle handle) const {
-  return impl->meshPool.get(handle);
-}
-
-MeshHandle AssetRegistry::loadMesh(std::vector<CanvasVertex> vertices,
-                                   std::vector<u32> indices) {
-  Mesh::Builder builder{};
-  builder.vertices.reserve(vertices.size());
-  for (const CanvasVertex& vertex : vertices) {
-    builder.vertices.push_back({vertex.position, vertex.color});
-  }
-  builder.indices = std::move(indices);
-
-  return impl->meshPool.create(builder);
-}
-
-}  // namespace sophia

engine/src/assets/pools/mesh_pool.cpp

@@ -1,58 +0,0 @@
-#include "assets/pools/mesh_pool.hpp"
-
-#include <sophia/util/assert.hpp>
-
-namespace sophia {
-
-namespace {
-constexpr u32 GENERATION_MASK = (1u << 12) - 1;
-}  // namespace
-
-MeshPool::MeshPool(Device& device) : device{device} {}
-
-MeshPool::~MeshPool() = default;
-
-MeshHandle MeshPool::create(const Mesh::Builder& builder) {
-  auto mesh = std::make_unique<Mesh>(device, builder);
-
-  if (!freeList.empty()) {
-    u32 index = freeList.back();
-    freeList.pop_back();
-    slots[index].mesh = std::move(mesh);
-    return MeshHandle{index, slots[index].generation};
-  }
-
-  slots.push_back(Slot{std::move(mesh), 0});
-  return MeshHandle{static_cast<u32>(slots.size() - 1), 0};
-}
-
-const Mesh& MeshPool::get(MeshHandle handle) const {
-  SOPHIA_ASSERT(handle.isValid(), "invalid MeshHandle");
-  SOPHIA_ASSERT(handle.index < slots.size(),
-                "MeshHandle index out of range:", handle.index);
-
-  const Slot& slot = slots[handle.index];
-  SOPHIA_ASSERT(slot.generation == handle.generation,
-                "stale MeshHandle (generation mismatch):", handle.index);
-  SOPHIA_ASSERT(slot.mesh != nullptr,
-                "MeshHandle refers to a released mesh:", handle.index);
-  return *slot.mesh;
-}
-
-void MeshPool::release(MeshHandle handle) {
-  SOPHIA_ASSERT(handle.isValid(), "invalid MeshHandle");
-  SOPHIA_ASSERT(handle.index < slots.size(),
-                "MeshHandle index out of range:", handle.index);
-
-  Slot& slot = slots[handle.index];
-  SOPHIA_ASSERT(slot.generation == handle.generation,
-                "stale MeshHandle (generation mismatch):", handle.index);
-  SOPHIA_ASSERT(slot.mesh != nullptr,
-                "MeshHandle already released:", handle.index);
-
-  slot.mesh.reset();
-  slot.generation = (slot.generation + 1) & GENERATION_MASK;
-  freeList.push_back(handle.index);
-}
-
-}  // namespace sophia

engine/src/assets/pools/mesh_pool.hpp

@@ -1,35 +0,0 @@
-#pragma once
-
-#include <memory>
-#include <vector>
-
-#include "device.hpp"
-#include "mesh.hpp"
-
-namespace sophia {
-
-class MeshPool {
- public:
-  explicit MeshPool(Device& device);
-  ~MeshPool();
-
-  MeshPool(const MeshPool&) = delete;
-  MeshPool& operator=(const MeshPool&) = delete;
-
-  MeshHandle create(const Mesh::Builder& builder);
-  const Mesh& get(MeshHandle handle) const;
-  void release(MeshHandle handle);
-
- private:
-  struct Slot {
-    std::unique_ptr<Mesh> mesh;
-    u32 generation = 0;
-  };
-
-  Device& device;
-
-  std::vector<Slot> slots;
-  std::vector<u32> freeList;
-};
-
-}  // namespace sophia

engine/src/rendering/imgui_renderer.cpp

@@ -1,10 +1,12 @@
-#include "imgui_renderer.hpp"
+#include "rendering/imgui_renderer.hpp"
 
 #include <imgui.h>
 #include <imgui_impl_glfw.h>
 #include <imgui_impl_vulkan.h>
 #include <imgui_internal.h>
 
+#include "resources/render_target.hpp"
+
 namespace sophia {
 
 namespace {
@@ -20,7 +22,8 @@ void dockAll(const std::vector<std::string>& windows, ImGuiID nodeId) {
 
 ImGuiRenderer::ImGuiRenderer(Window& window, Device& device,
                              vk::Format colorAttachmentFormat,
-                             u32 minImageCount) {
+                             u32 minImageCount, ResourceRegistry& resources)
+    : resources{resources} {
   // 1. Construct ImGui context
   IMGUI_CHECKVERSION();
   ImGui::CreateContext();
@@ -67,12 +70,17 @@ ImGuiRenderer::ImGuiRenderer(Window& window, Device& device,
 }
 
 ImGuiRenderer::~ImGuiRenderer() {
+  for (const auto& [index, texture] : textures) {
+    ImGui_ImplVulkan_RemoveTexture(texture.descriptorSet);
+  }
   ImGui_ImplVulkan_Shutdown();
   ImGui_ImplGlfw_Shutdown();
   ImGui::DestroyContext();
 }
 
 void ImGuiRenderer::beginFrame() {
+  releaseStaleTextures();
+
   ImGui_ImplVulkan_NewFrame();
   ImGui_ImplGlfw_NewFrame();
   ImGui::NewFrame();
@@ -82,6 +90,46 @@ void ImGuiRenderer::beginFrame() {
   applyLayoutIfNeeded(dockspaceId, DOCKSPACE_FLAGS);
 }
 
+ImTextureID ImGuiRenderer::getTextureId(RenderTargetHandle handle) {
+  vk::ImageView view =
+      resources.renderTargetPool.get(handle).getImage().getView();
+
+  auto it = textures.find(handle.index);
+  if (it != textures.end()) {
+    if (it->second.generation == handle.generation && it->second.view == view) {
+      return (ImTextureID)it->second.descriptorSet;
+    }
+    ImGui_ImplVulkan_RemoveTexture(it->second.descriptorSet);
+    textures.erase(it);
+  }
+
+  // ImGui owns the sampler; it only needs the view and the layout the image is
+  // left in once the scene pass has finished.
+  VkDescriptorSet descriptorSet = ImGui_ImplVulkan_AddTexture(
+      static_cast<VkImageView>(view), VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL);
+  textures[handle.index] = {handle.generation, view, descriptorSet};
+  return (ImTextureID)descriptorSet;
+}
+
+// Resizing and releasing a target both wait for the GPU before destroying its
+// image, so nothing in flight can still be using a stale texture.
+void ImGuiRenderer::releaseStaleTextures() {
+  for (auto it = textures.begin(); it != textures.end();) {
+    RenderTargetHandle handle{it->first, it->second.generation};
+    RenderTargetPool& renderTargetPool = resources.renderTargetPool;
+
+    bool stale =
+        !renderTargetPool.isAlive(handle) ||
+        renderTargetPool.get(handle).getImage().getView() != it->second.view;
+    if (stale) {
+      ImGui_ImplVulkan_RemoveTexture(it->second.descriptorSet);
+      it = textures.erase(it);
+    } else {
+      ++it;
+    }
+  }
+}
+
 void ImGuiRenderer::setDefaultLayout(DockLayout layout) {
   defaultLayout = std::move(layout);
   seedIfUnsaved = true;

engine/src/rendering/imgui_renderer.hpp

@@ -2,10 +2,13 @@
 
 #include <imgui.h>
 
+#include <sophia/handles.hpp>
 #include <sophia/types.hpp>
 #include <sophia/ui/dock_layout.hpp>
+#include <unordered_map>
 
-#include "device.hpp"
+#include "resources/resource_registry.hpp"
+#include "vulkan/device.hpp"
 #include "window.hpp"
 
 namespace sophia {
@@ -16,17 +19,32 @@ class ImGuiRenderer {
   ImGuiRenderer& operator=(const ImGuiRenderer&) = delete;
 
   ImGuiRenderer(Window& window, Device& device,
-                vk::Format colorAttachmentFormat, u32 minImageCount);
+                vk::Format colorAttachmentFormat, u32 minImageCount,
+                ResourceRegistry& resources);
   ~ImGuiRenderer();
 
   void beginFrame();
   void endFrame(vk::CommandBuffer commandBuffer);
 
+  ImTextureID getTextureId(RenderTargetHandle handle);
+
   void setDefaultLayout(DockLayout layout);
   void resetLayout();
 
  private:
   void applyLayoutIfNeeded(ImGuiID dockspaceId, ImGuiDockNodeFlags flags);
+  void releaseStaleTextures();
+
+  struct Texture {
+    u32 generation;
+    vk::ImageView view;
+    VkDescriptorSet descriptorSet;
+  };
+
+  ResourceRegistry& resources;
+
+  // Keyed by RenderTargetHandle::index.
+  std::unordered_map<u32, Texture> textures;
 
   DockLayout defaultLayout;
   bool seedIfUnsaved = false;

engine/src/rendering/model_render_system.cpp

@@ -1,4 +1,4 @@
-#include "model_render_system.hpp"
+#include "rendering/model_render_system.hpp"
 
 #include <sophia/util/assert.hpp>
 

engine/src/rendering/model_render_system.hpp

@@ -4,10 +4,10 @@
 #include <sophia/frame_info.hpp>
 #include <span>
 
-#include "device.hpp"
-#include "mesh.hpp"
-#include "pipelines/graphics_pipeline.hpp"
-#include "render_context.hpp"
+#include "rendering/render_context.hpp"
+#include "resources/mesh.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/pipelines/graphics_pipeline.hpp"
 
 namespace sophia {
 

engine/src/rendering/render_context.cpp

@@ -1,10 +1,12 @@
-#include "render_context.hpp"
+#include "rendering/render_context.hpp"
 
 #include <limits>
 #include <sophia/util/assert.hpp>
 #include <sophia/util/logger.hpp>
 #include <stdexcept>
 
+#include "vulkan/access.hpp"
+
 namespace sophia {
 
 RenderContext::RenderContext(Window& window, Device& device)
@@ -80,8 +82,7 @@ void RenderContext::endFrame() {
   vk::Semaphore waitSemaphore = frame.imageAvailable.get();
   vk::Semaphore signalSemaphore =
       this->renderFinishedSemaphores.at(this->currentImageIndex).get();
-  vk::PipelineStageFlags waitStage =
-      vk::PipelineStageFlagBits::eColorAttachmentOutput;
+  vk::PipelineStageFlags waitStage = SWAPCHAIN_ACQUIRE_STAGE;
   vk::CommandBuffer commandBuffer = frame.commandBuffer;
 
   vk::SubmitInfo submitInfo{};

engine/src/rendering/render_context.hpp

@@ -6,8 +6,8 @@
 #include <vector>
 #include <vulkan/vulkan.hpp>
 
-#include "device.hpp"
-#include "swapchain.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/swapchain.hpp"
 #include "window.hpp"
 
 namespace sophia {
@@ -31,14 +31,8 @@ class RenderContext {
   vk::CommandBuffer beginFrame();
   void endFrame();
 
-  void transitionCurrentImage(vk::CommandBuffer commandBuffer,
-                              vk::ImageLayout newLayout) const {
-    this->swapchain->getImage(static_cast<int>(this->currentImageIndex))
-        .transitionLayout(commandBuffer, newLayout);
-  }
-  vk::ImageView getCurrentImageView() const {
-    return this->swapchain->getImageView(
-        static_cast<int>(this->currentImageIndex));
+  Image& getCurrentImage() const {
+    return this->swapchain->getImage(static_cast<int>(this->currentImageIndex));
   }
 
   vk::Extent2D getExtent() const { return this->swapchain->getExtent(); }

engine/src/rendering/render_graph.cpp

@@ -0,0 +1,168 @@
+#include "rendering/render_graph.hpp"
+
+#include <sophia/util/assert.hpp>
+#include <utility>
+
+#include "vulkan/debug_label.hpp"
+
+namespace sophia {
+
+ImageRef RenderGraph::importImage(Image& image, Access finalAccess) {
+  ImageRef ref{static_cast<u32>(this->images.size())};
+  this->images.push_back({&image, finalAccess, image.getAccessState()});
+  return ref;
+}
+
+void RenderGraph::addPass(std::string name, const SetupFn& setup,
+                          ExecuteFn execute) {
+  Pass& pass = this->passes.emplace_back();
+  pass.name = std::move(name);
+  pass.execute = std::move(execute);
+
+  PassBuilder builder{*this, pass};
+  setup(builder);
+}
+
+void RenderGraph::execute(vk::CommandBuffer commandBuffer) {
+  for (Pass& pass : this->passes) {
+    this->recordPass(commandBuffer, pass);
+  }
+
+  PendingBarriers pending;
+  for (u32 i = 0; i < this->images.size(); i++) {
+    this->transitionTo(ImageRef{i}, getAccessState(this->images[i].finalAccess),
+                       pending);
+  }
+  this->flush(commandBuffer, pending);
+
+  for (ImportedImage& imported : this->images) {
+    imported.image->recordLayout(imported.state.layout);
+  }
+
+  this->passes.clear();
+}
+
+void RenderGraph::transitionTo(ImageRef ref, const AccessState& next,
+                               PendingBarriers& pending) {
+  SOPHIA_ASSERT(ref.isValid() && ref.index < this->images.size(),
+                "ImageRef doesn't belong to this graph");
+
+  ImportedImage& imported = this->images[ref.index];
+
+  if (needsBarrier(imported.state, next)) {
+    pending.barriers.push_back(makeImageBarrier(
+        imported.image->get(), imported.image->getSubresourceRange(),
+        imported.state, next));
+    pending.srcStages |= imported.state.stage;
+    pending.dstStages |= next.stage;
+    imported.state = next;
+  } else {
+    // Same-layout read after read. Nothing to record, but a later write has
+    // to wait on this reader too.
+    imported.state.stage |= next.stage;
+    imported.state.access |= next.access;
+  }
+}
+
+void RenderGraph::flush(vk::CommandBuffer commandBuffer,
+                        PendingBarriers& pending) {
+  if (pending.barriers.empty()) {
+    return;
+  }
+
+  commandBuffer.pipelineBarrier(pending.srcStages, pending.dstStages, {},
+                                nullptr, nullptr, pending.barriers);
+  pending = PendingBarriers{};
+}
+
+void RenderGraph::recordPass(vk::CommandBuffer commandBuffer, Pass& pass) {
+  beginDebugLabel(commandBuffer, pass.name.c_str());
+
+  PendingBarriers pending;
+  for (const ImageUse& use : pass.uses) {
+    this->transitionTo(use.image, getAccessState(use.access), pending);
+  }
+  this->flush(commandBuffer, pending);
+
+  if (pass.colorAttachments.empty()) {
+    pass.execute(commandBuffer);
+  } else {
+    this->recordRendering(commandBuffer, pass);
+  }
+
+  endDebugLabel(commandBuffer);
+}
+
+void RenderGraph::recordRendering(vk::CommandBuffer commandBuffer, Pass& pass) {
+  std::vector<vk::RenderingAttachmentInfo> attachments;
+  attachments.reserve(pass.colorAttachments.size());
+
+  vk::Extent3D imageExtent =
+      this->images[pass.colorAttachments.front().image.index]
+          .image->getExtent();
+  vk::Extent2D extent{imageExtent.width, imageExtent.height};
+
+  for (const ColorAttachment& color : pass.colorAttachments) {
+    const Image& image = *this->images[color.image.index].image;
+    SOPHIA_ASSERT(image.getExtent().width == extent.width &&
+                      image.getExtent().height == extent.height,
+                  "Pass", pass.name,
+                  "has color attachments of different sizes");
+
+    vk::RenderingAttachmentInfo attachment{};
+    attachment.imageView = image.getView();
+    attachment.imageLayout = vk::ImageLayout::eColorAttachmentOptimal;
+    attachment.loadOp = color.loadOp;
+    attachment.storeOp = vk::AttachmentStoreOp::eStore;
+    attachment.clearValue.color = vk::ClearColorValue{color.clearColor};
+    attachments.push_back(attachment);
+  }
+
+  vk::RenderingInfo renderingInfo{};
+  renderingInfo.renderArea = vk::Rect2D{{0, 0}, extent};
+  renderingInfo.layerCount = 1;
+  renderingInfo.colorAttachmentCount = static_cast<u32>(attachments.size());
+  renderingInfo.pColorAttachments = attachments.data();
+
+  commandBuffer.beginRendering(renderingInfo);
+
+  vk::Viewport viewport{0.0f,
+                        0.0f,
+                        static_cast<float>(extent.width),
+                        static_cast<float>(extent.height),
+                        0.0f,
+                        1.0f};
+  vk::Rect2D scissor{{0, 0}, extent};
+  commandBuffer.setViewport(0, viewport);
+  commandBuffer.setScissor(0, scissor);
+
+  pass.execute(commandBuffer);
+
+  commandBuffer.endRendering();
+}
+
+RenderGraph::PassBuilder& RenderGraph::PassBuilder::writeColor(
+    ImageRef image, vk::AttachmentLoadOp loadOp, ClearColor clearColor) {
+  this->use(image, Access::ColorWrite);
+  this->pass.colorAttachments.push_back({image, loadOp, clearColor});
+  return *this;
+}
+
+RenderGraph::PassBuilder& RenderGraph::PassBuilder::sample(ImageRef image) {
+  return this->use(image, Access::SampledRead);
+}
+
+RenderGraph::PassBuilder& RenderGraph::PassBuilder::use(ImageRef image,
+                                                        Access access) {
+  SOPHIA_ASSERT(image.isValid() && image.index < this->graph.images.size(),
+                "ImageRef doesn't belong to this graph");
+  for (const ImageUse& existing : this->pass.uses) {
+    SOPHIA_ASSERT(existing.image.index != image.index, "Pass", this->pass.name,
+                  "uses the same image twice");
+  }
+
+  this->pass.uses.push_back({image, access});
+  return *this;
+}
+
+}  // namespace sophia

engine/src/rendering/render_graph.hpp

@@ -0,0 +1,149 @@
+#pragma once
+
+#include <array>
+#include <functional>
+#include <sophia/types.hpp>
+#include <string>
+#include <vector>
+#include <vulkan/vulkan.hpp>
+
+#include "vulkan/access.hpp"
+#include "vulkan/image.hpp"
+
+namespace sophia {
+
+/**
+ * Names an image within one RenderGraph. Only valid for the graph that
+ * returned it.
+ */
+struct ImageRef {
+  u32 index = INVALID_INDEX;
+
+  static constexpr u32 INVALID_INDEX = 0xFFFFFFFF;
+
+  bool isValid() const { return this->index != INVALID_INDEX; }
+};
+
+using ClearColor = std::array<float, 4>;
+
+/**
+ * A frame's passes and the images they touch, recorded into a single command
+ * buffer. Passes run in the order they were added; the graph's job is to
+ * work out the barriers and layout transitions between them from what each
+ * pass says it does to each image, and to begin/end rendering for passes that
+ * write color attachments.
+ *
+ * Built fresh every frame:
+ *
+ *   RenderGraph graph;
+ *   ImageRef backbuffer = graph.importImage(swapchainImage, Access::Present);
+ *   graph.addPass(
+ *       "main", [&](PassBuilder& pass) { pass.writeColor(backbuffer); },
+ *       [&](vk::CommandBuffer cb) { draw(cb); });
+ *   graph.execute(commandBuffer);
+ *
+ * Imported images start in whatever layout Image reports and are left in
+ * their final access when execute() returns, with the Image's tracked layout
+ * updated to match.
+ */
+class RenderGraph {
+ public:
+  class PassBuilder;
+
+  using SetupFn = std::function<void(PassBuilder&)>;
+  using ExecuteFn = std::function<void(vk::CommandBuffer)>;
+
+  RenderGraph() = default;
+
+  RenderGraph(const RenderGraph&) = delete;
+  RenderGraph& operator=(const RenderGraph&) = delete;
+
+  /**
+   * Brings an image the graph doesn't own into it. It must outlive
+   * execute(). After the last pass it is transitioned to `finalAccess`.
+   */
+  ImageRef importImage(Image& image, Access finalAccess);
+
+  /**
+   * Adds a pass. `setup` runs immediately and declares what the pass does to
+   * images; `execute` runs later, from execute(), with the barriers already
+   * recorded and (if the pass writes color) rendering begun. `name` labels
+   * the pass's commands in debugging tools such as RenderDoc.
+   */
+  void addPass(std::string name, const SetupFn& setup, ExecuteFn execute);
+
+  /**
+   * Records every pass, and the barriers between them, into `commandBuffer`.
+   */
+  void execute(vk::CommandBuffer commandBuffer);
+
+ private:
+  struct ImageUse {
+    ImageRef image;
+    Access access;
+  };
+
+  struct ColorAttachment {
+    ImageRef image;
+    vk::AttachmentLoadOp loadOp;
+    ClearColor clearColor;
+  };
+
+  struct Pass {
+    std::string name;
+    std::vector<ImageUse> uses;
+    std::vector<ColorAttachment> colorAttachments;
+    ExecuteFn execute;
+  };
+
+  struct ImportedImage {
+    Image* image;
+    Access finalAccess;
+    // What the image was last left in, as of the barriers recorded so far.
+    AccessState state;
+  };
+
+  struct PendingBarriers {
+    std::vector<vk::ImageMemoryBarrier> barriers;
+    vk::PipelineStageFlags srcStages;
+    vk::PipelineStageFlags dstStages;
+  };
+
+  void transitionTo(ImageRef ref, const AccessState& next,
+                    PendingBarriers& pending);
+  void flush(vk::CommandBuffer commandBuffer, PendingBarriers& pending);
+  void recordPass(vk::CommandBuffer commandBuffer, Pass& pass);
+  void recordRendering(vk::CommandBuffer commandBuffer, Pass& pass);
+
+  std::vector<ImportedImage> images;
+  std::vector<Pass> passes;
+};
+
+class RenderGraph::PassBuilder {
+ public:
+  /**
+   * Renders into `image` as a color attachment. Passes with one or more of
+   * these get rendering begun (and viewport/scissor set to the attachment's
+   * extent) before their execute callback runs.
+   */
+  PassBuilder& writeColor(
+      ImageRef image,
+      vk::AttachmentLoadOp loadOp = vk::AttachmentLoadOp::eClear,
+      ClearColor clearColor = {0.f, 0.f, 0.f, 1.f});
+
+  /** Samples `image` in a shader. */
+  PassBuilder& sample(ImageRef image);
+
+  /** Any other use, e.g. storage or transfer access. */
+  PassBuilder& use(ImageRef image, Access access);
+
+ private:
+  friend class RenderGraph;
+
+  PassBuilder(RenderGraph& graph, Pass& pass) : graph{graph}, pass{pass} {}
+
+  RenderGraph& graph;
+  Pass& pass;
+};
+
+}  // namespace sophia

engine/src/rendering/scene_renderer.cpp

@@ -0,0 +1,74 @@
+#include "rendering/scene_renderer.hpp"
+
+#include <sophia/components.hpp>
+#include <sophia/util/assert.hpp>
+
+namespace sophia {
+
+namespace {
+struct PushConstantData {
+  glm::mat4 transform{1.f};
+  glm::vec4 color{1.f};
+};
+}  // namespace
+
+SceneRenderer::SceneRenderer(const SceneRegistry& sceneRegistry,
+                             ResourceRegistry& resources)
+    : sceneRegistry{sceneRegistry}, resources{resources} {}
+
+SceneRenderer::~SceneRenderer() {}
+
+void SceneRenderer::render(SceneView sceneView) {
+  auto& handle = sceneView.scene;
+  auto& scene = this->sceneRegistry.get(handle);
+
+  auto& camera = sceneView.camera;
+  SOPHIA_ASSERT(camera.hasComponent<CameraComponent>(),
+                "camera does not have camera component!");
+
+  auto& registry = scene.registry;
+
+  auto view = registry.view<MeshComponent, TransformComponent>();
+
+  for (auto entity : view) {
+    auto& transform = view.get<TransformComponent>(entity);
+    log::info(transform);
+  }
+
+  // Get all mesh
+  // For each mesh, get all entities(ES) that have a transform and that mesh
+  // For e in ES: add e's transform component to a list
+
+  // We now have
+  /*
+  M = mesh
+  T = transform
+
+  Work Batch
+  |- M0
+  |  |- T0
+  |  \- T2
+  |
+  |- M1
+  |  |- T1
+  |  \- T5
+  |
+  \- M2
+     |- T3
+     \- T4
+
+  */
+
+  /*
+  for batch in Work Batch:
+      batch.mesh.bind()
+
+      for transform in batch.transforms:
+          commandBuffer.pushConstants(transform)
+          batch.mesh.draw(commandBuffer)
+
+  NOTE: Use instanced rendering?
+  */
+}
+
+}  // namespace sophia

engine/src/rendering/scene_renderer.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <sophia/scene_registry.hpp>
+#include <sophia/scene_view.hpp>
+
+#include "resources/resource_registry.hpp"
+
+namespace sophia {
+
+/**
+ * !TEMP to be decoupled once scene batching and rendering impl
+ */
+class SceneRenderer {
+ public:
+  SceneRenderer(const SceneRenderer&) = delete;
+  SceneRenderer& operator=(const SceneRenderer&) = delete;
+
+  SceneRenderer(const SceneRegistry& sceneRegistry,
+                ResourceRegistry& resources);
+  ~SceneRenderer();
+
+  void render(SceneView sceneView);
+
+ private:
+  const SceneRegistry& sceneRegistry;
+  ResourceRegistry& resources;
+};
+
+}  // namespace sophia

engine/src/resources/mesh.cpp

@@ -1,4 +1,4 @@
-#include "mesh.hpp"
+#include "resources/mesh.hpp"
 
 #include <sophia/util/assert.hpp>
 #include <sophia/util/logger.hpp>

engine/src/resources/mesh.hpp

@@ -1,23 +1,18 @@
 #pragma once
 
 #include <memory>
-#include <sophia/asset_registry.hpp>
+#include <sophia/handles.hpp>
+#include <sophia/math.hpp>
 #include <sophia/types.hpp>
 #include <vector>
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-
-#include "buffer.hpp"
-#include "device.hpp"
+#include "vulkan/buffer.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 
 class Mesh {
  public:
-  using HandleType = MeshHandle;
-
   struct Vertex {
     glm::vec2 position{};
     glm::vec3 color{};

engine/src/resources/pools/render_target_pool.cpp

@@ -0,0 +1,22 @@
+#include "resources/pools/render_target_pool.hpp"
+
+namespace sophia {
+
+RenderTargetPool::RenderTargetPool(Device& device, vk::Format format)
+    : device{device}, format{format} {}
+
+RenderTargetHandle RenderTargetPool::create(u32 width, u32 height) {
+  return pool.create(device, format, width, height);
+}
+
+void RenderTargetPool::release(RenderTargetHandle handle) {
+  SOPHIA_ASSERT(pool.isAlive(handle), "invalid RenderTargetHandle");
+  device.waitIdle();
+  pool.release(handle);
+}
+
+void RenderTargetPool::applyPendingResizes() {
+  pool.forEach([](RenderTarget& target) { target.applyPendingResize(); });
+}
+
+}  // namespace sophia

engine/src/resources/pools/render_target_pool.hpp

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <sophia/handles.hpp>
+#include <sophia/util/pool.hpp>
+
+#include "resources/render_target.hpp"
+#include "vulkan/device.hpp"
+
+namespace sophia {
+
+class RenderTargetPool {
+ public:
+  RenderTargetPool(Device& device, vk::Format format);
+
+  RenderTargetPool(const RenderTargetPool&) = delete;
+  RenderTargetPool& operator=(const RenderTargetPool&) = delete;
+
+  RenderTargetHandle create(u32 width, u32 height);
+  RenderTarget& get(RenderTargetHandle handle) { return pool.get(handle); }
+  const RenderTarget& get(RenderTargetHandle handle) const {
+    return pool.get(handle);
+  }
+  void release(RenderTargetHandle handle);
+
+  bool isAlive(RenderTargetHandle handle) const { return pool.isAlive(handle); }
+
+  void applyPendingResizes();
+
+ private:
+  Device& device;
+  vk::Format format;
+
+  Pool<RenderTarget> pool{"RenderTarget"};
+};
+
+}  // namespace sophia

engine/src/resources/render_target.cpp

@@ -0,0 +1,52 @@
+#include "resources/render_target.hpp"
+
+#include <algorithm>
+
+namespace sophia {
+
+RenderTarget::RenderTarget(Device& device, vk::Format format, u32 width,
+                           u32 height)
+    : device{device}, format{format} {
+  create(std::max(width, 1u), std::max(height, 1u));
+}
+
+RenderTarget::~RenderTarget() { destroy(); }
+
+vk::Extent2D RenderTarget::getExtent() const {
+  vk::Extent3D extent = this->image->getExtent();
+  return {extent.width, extent.height};
+}
+
+void RenderTarget::requestResize(u32 width, u32 height) {
+  this->pendingExtent = vk::Extent2D{std::max(width, 1u), std::max(height, 1u)};
+}
+
+void RenderTarget::applyPendingResize() {
+  if (!this->pendingExtent) {
+    return;
+  }
+
+  vk::Extent2D extent = *this->pendingExtent;
+  this->pendingExtent.reset();
+  if (extent == getExtent()) {
+    return;
+  }
+
+  this->device.waitIdle();
+
+  destroy();
+  create(extent.width, extent.height);
+}
+
+void RenderTarget::create(u32 width, u32 height) {
+  this->image = Image::Builder(this->device)
+                    .setExtent(width, height)
+                    .setFormat(this->format)
+                    .asColorAttachment()
+                    .withView()
+                    .build();
+}
+
+void RenderTarget::destroy() { this->image.reset(); }
+
+}  // namespace sophia

engine/src/resources/render_target.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <memory>
+#include <optional>
+#include <sophia/types.hpp>
+#include <vulkan/vulkan.hpp>
+
+#include "vulkan/device.hpp"
+#include "vulkan/image.hpp"
+
+namespace sophia {
+
+/**
+ * A place rendering can go. Currently always backed by an offscreen color
+ * image.
+ *
+ * Owned by the ResourceRegistry and addressed through a RenderTargetHandle.
+ */
+class RenderTarget {
+ public:
+  RenderTarget(Device& device, vk::Format format, u32 width, u32 height);
+  ~RenderTarget();
+
+  RenderTarget(const RenderTarget&) = delete;
+  RenderTarget& operator=(const RenderTarget&) = delete;
+
+  Image& getImage() const { return *this->image; }
+
+  vk::Extent2D getExtent() const;
+
+  void requestResize(u32 width, u32 height);
+
+  /**
+   * Applies a pending resize. Waits for the GPU, so it must run before any of
+   * the frame's work (or any UI reference to the image) is recorded.
+   */
+  void applyPendingResize();
+
+ private:
+  void create(u32 width, u32 height);
+  void destroy();
+
+  Device& device;
+  vk::Format format;
+
+  std::unique_ptr<Image> image;
+
+  std::optional<vk::Extent2D> pendingExtent;
+};
+
+}  // namespace sophia

engine/src/resources/resource_registry.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <sophia/handles.hpp>
+#include <sophia/util/pool.hpp>
+
+#include "resources/mesh.hpp"
+#include "resources/pools/render_target_pool.hpp"
+#include "vulkan/device.hpp"
+
+namespace sophia {
+
+class ResourceRegistry {
+ public:
+  ResourceRegistry(const ResourceRegistry&) = delete;
+  ResourceRegistry& operator=(const ResourceRegistry&) = delete;
+
+  ResourceRegistry(Device& device, vk::Format renderTargetFormat)
+      : device{device}, renderTargetPool{device, renderTargetFormat} {}
+
+  Device& device;
+  Pool<Mesh> meshPool{"Mesh"};
+  RenderTargetPool renderTargetPool;
+  // TexturePool textures;
+  // MaterialPool materials;
+};
+
+}  // namespace sophia

engine/src/resources/resource_registry_ref.cpp

@@ -0,0 +1,59 @@
+#include <sophia/resource_registry_ref.hpp>
+#include <sophia/util/assert.hpp>
+
+#include "resources/resource_registry.hpp"
+
+namespace sophia {
+
+template <>
+MeshHandle ResourceRegistryRef::load<Mesh>(const std::string& path) {
+  (void)path;
+  SOPHIA_ASSERT(false,
+                "Mesh::load(path) is not implemented yet - no model file "
+                "format is supported; build one via Mesh::Builder for now");
+  return MeshHandle{};
+}
+
+template <>
+void ResourceRegistryRef::release<Mesh>(MeshHandle handle) {
+  registry->meshPool.release(handle);
+}
+
+template <>
+void ResourceRegistryRef::release<RenderTarget>(RenderTargetHandle handle) {
+  registry->renderTargetPool.release(handle);
+}
+
+MeshHandle ResourceRegistryRef::createResource(
+    std::type_identity<Mesh>, std::vector<CanvasVertex> vertices,
+    std::vector<u32> indices) {
+  Mesh::Builder builder{};
+  builder.vertices.reserve(vertices.size());
+  for (const CanvasVertex& vertex : vertices) {
+    builder.vertices.push_back({vertex.position, vertex.color});
+  }
+  builder.indices = std::move(indices);
+
+  return registry->meshPool.create(registry->device, builder);
+}
+
+RenderTargetHandle ResourceRegistryRef::createResource(
+    std::type_identity<RenderTarget>, u32 width, u32 height) {
+  return registry->renderTargetPool.create(width, height);
+}
+
+void ResourceRegistryRef::requestResize(RenderTargetHandle handle, u32 width,
+                                        u32 height) {
+  registry->renderTargetPool.get(handle).requestResize(width, height);
+}
+
+glm::vec2 ResourceRegistryRef::getExtent(RenderTargetHandle handle) const {
+  vk::Extent2D extent = registry->renderTargetPool.get(handle).getExtent();
+  return {static_cast<float>(extent.width), static_cast<float>(extent.height)};
+}
+
+bool ResourceRegistryRef::isAlive(RenderTargetHandle handle) const {
+  return registry->renderTargetPool.isAlive(handle);
+}
+
+}  // namespace sophia

engine/src/scene.hpp

@@ -1,16 +0,0 @@
-#pragma once
-
-#include <entt/entt.hpp>
-
-namespace sophia {
-
-class Scene {
- public:
-  Scene();
-  ~Scene();
-
- private:
-  entt::registry registry;
-};
-
-}  // namespace sophia

engine/src/scene/entity.cpp

@@ -0,0 +1,8 @@
+#include <sophia/entity.hpp>
+
+namespace sophia {
+
+Entity::Entity(entt::entity handle, Scene* scene)
+    : handle(handle), scene(scene) {}
+
+}  // namespace sophia

engine/src/scene/scene.cpp

@@ -1,6 +1,5 @@
-#include "scene.hpp"
-
 #include <sophia/components.hpp>
+#include <sophia/scene.hpp>
 #include <sophia/util/logger.hpp>
 
 namespace sophia {

engine/src/shaders/fullscreen.vert.spv.h

@@ -0,0 +1,100 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+
+namespace sophia::shaders {
+
+inline constexpr std::array<uint32_t, 355> fullscreen_vert_spv = {
+    0x07230203, 0x00010000, 0x000d000b, 0x00000032,
+    0x00000000, 0x00020011, 0x00000001, 0x0006000b,
+    0x00000001, 0x4c534c47, 0x6474732e, 0x3035342e,
+    0x00000000, 0x0003000e, 0x00000000, 0x00000001,
+    0x0008000f, 0x00000000, 0x00000004, 0x6e69616d,
+    0x00000000, 0x00000018, 0x00000022, 0x0000002c,
+    0x00030003, 0x00000002, 0x000001c2, 0x000a0004,
+    0x475f4c47, 0x4c474f4f, 0x70635f45, 0x74735f70,
+    0x5f656c79, 0x656e696c, 0x7269645f, 0x69746365,
+    0x00006576, 0x00080004, 0x475f4c47, 0x4c474f4f,
+    0x6e695f45, 0x64756c63, 0x69645f65, 0x74636572,
+    0x00657669, 0x00040005, 0x00000004, 0x6e69616d,
+    0x00000000, 0x00050005, 0x0000000c, 0x69736f70,
+    0x6e6f6974, 0x00000073, 0x00030005, 0x00000015,
+    0x00736f70, 0x00060005, 0x00000018, 0x565f6c67,
+    0x65747265, 0x646e4978, 0x00007865, 0x00060005,
+    0x00000020, 0x505f6c67, 0x65567265, 0x78657472,
+    0x00000000, 0x00060006, 0x00000020, 0x00000000,
+    0x505f6c67, 0x7469736f, 0x006e6f69, 0x00070006,
+    0x00000020, 0x00000001, 0x505f6c67, 0x746e696f,
+    0x657a6953, 0x00000000, 0x00070006, 0x00000020,
+    0x00000002, 0x435f6c67, 0x4470696c, 0x61747369,
+    0x0065636e, 0x00070006, 0x00000020, 0x00000003,
+    0x435f6c67, 0x446c6c75, 0x61747369, 0x0065636e,
+    0x00030005, 0x00000022, 0x00000000, 0x00030005,
+    0x0000002c, 0x00007675, 0x00040047, 0x00000018,
+    0x0000000b, 0x0000002a, 0x00030047, 0x00000020,
+    0x00000002, 0x00050048, 0x00000020, 0x00000000,
+    0x0000000b, 0x00000000, 0x00050048, 0x00000020,
+    0x00000001, 0x0000000b, 0x00000001, 0x00050048,
+    0x00000020, 0x00000002, 0x0000000b, 0x00000003,
+    0x00050048, 0x00000020, 0x00000003, 0x0000000b,
+    0x00000004, 0x00040047, 0x0000002c, 0x0000001e,
+    0x00000000, 0x00020013, 0x00000002, 0x00030021,
+    0x00000003, 0x00000002, 0x00030016, 0x00000006,
+    0x00000020, 0x00040017, 0x00000007, 0x00000006,
+    0x00000002, 0x00040015, 0x00000008, 0x00000020,
+    0x00000000, 0x0004002b, 0x00000008, 0x00000009,
+    0x00000006, 0x0004001c, 0x0000000a, 0x00000007,
+    0x00000009, 0x00040020, 0x0000000b, 0x00000006,
+    0x0000000a, 0x0004003b, 0x0000000b, 0x0000000c,
+    0x00000006, 0x0004002b, 0x00000006, 0x0000000d,
+    0xbf800000, 0x0005002c, 0x00000007, 0x0000000e,
+    0x0000000d, 0x0000000d, 0x0004002b, 0x00000006,
+    0x0000000f, 0x3f800000, 0x0005002c, 0x00000007,
+    0x00000010, 0x0000000f, 0x0000000d, 0x0005002c,
+    0x00000007, 0x00000011, 0x0000000d, 0x0000000f,
+    0x0005002c, 0x00000007, 0x00000012, 0x0000000f,
+    0x0000000f, 0x0009002c, 0x0000000a, 0x00000013,
+    0x0000000e, 0x00000010, 0x00000011, 0x00000011,
+    0x00000010, 0x00000012, 0x00040020, 0x00000014,
+    0x00000007, 0x00000007, 0x00040015, 0x00000016,
+    0x00000020, 0x00000001, 0x00040020, 0x00000017,
+    0x00000001, 0x00000016, 0x0004003b, 0x00000017,
+    0x00000018, 0x00000001, 0x00040020, 0x0000001a,
+    0x00000006, 0x00000007, 0x00040017, 0x0000001d,
+    0x00000006, 0x00000004, 0x0004002b, 0x00000008,
+    0x0000001e, 0x00000001, 0x0004001c, 0x0000001f,
+    0x00000006, 0x0000001e, 0x0006001e, 0x00000020,
+    0x0000001d, 0x00000006, 0x0000001f, 0x0000001f,
+    0x00040020, 0x00000021, 0x00000003, 0x00000020,
+    0x0004003b, 0x00000021, 0x00000022, 0x00000003,
+    0x0004002b, 0x00000016, 0x00000023, 0x00000000,
+    0x0004002b, 0x00000006, 0x00000025, 0x00000000,
+    0x00040020, 0x00000029, 0x00000003, 0x0000001d,
+    0x00040020, 0x0000002b, 0x00000003, 0x00000007,
+    0x0004003b, 0x0000002b, 0x0000002c, 0x00000003,
+    0x0004002b, 0x00000006, 0x0000002e, 0x3f000000,
+    0x00050036, 0x00000002, 0x00000004, 0x00000000,
+    0x00000003, 0x000200f8, 0x00000005, 0x0004003b,
+    0x00000014, 0x00000015, 0x00000007, 0x0003003e,
+    0x0000000c, 0x00000013, 0x0004003d, 0x00000016,
+    0x00000019, 0x00000018, 0x00050041, 0x0000001a,
+    0x0000001b, 0x0000000c, 0x00000019, 0x0004003d,
+    0x00000007, 0x0000001c, 0x0000001b, 0x0003003e,
+    0x00000015, 0x0000001c, 0x0004003d, 0x00000007,
+    0x00000024, 0x00000015, 0x00050051, 0x00000006,
+    0x00000026, 0x00000024, 0x00000000, 0x00050051,
+    0x00000006, 0x00000027, 0x00000024, 0x00000001,
+    0x00070050, 0x0000001d, 0x00000028, 0x00000026,
+    0x00000027, 0x00000025, 0x0000000f, 0x00050041,
+    0x00000029, 0x0000002a, 0x00000022, 0x00000023,
+    0x0003003e, 0x0000002a, 0x00000028, 0x0004003d,
+    0x00000007, 0x0000002d, 0x00000015, 0x0005008e,
+    0x00000007, 0x0000002f, 0x0000002d, 0x0000002e,
+    0x00050050, 0x00000007, 0x00000030, 0x0000002e,
+    0x0000002e, 0x00050081, 0x00000007, 0x00000031,
+    0x0000002f, 0x00000030, 0x0003003e, 0x0000002c,
+    0x00000031, 0x000100fd, 0x00010038,
+};
+
+}  // namespace sophia::shaders

engine/src/shaders/model_render_system.frag.spv.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+
+namespace sophia::shaders {
+
+inline constexpr std::array<uint32_t, 143> model_render_system_frag_spv = {
+    0x07230203, 0x00010000, 0x000d000b, 0x00000013, 0x00000000, 0x00020011,
+    0x00000001, 0x0006000b, 0x00000001, 0x4c534c47, 0x6474732e, 0x3035342e,
+    0x00000000, 0x0003000e, 0x00000000, 0x00000001, 0x0007000f, 0x00000004,
+    0x00000004, 0x6e69616d, 0x00000000, 0x00000009, 0x0000000c, 0x00030010,
+    0x00000004, 0x00000007, 0x00030003, 0x00000002, 0x000001c2, 0x000a0004,
+    0x475f4c47, 0x4c474f4f, 0x70635f45, 0x74735f70, 0x5f656c79, 0x656e696c,
+    0x7269645f, 0x69746365, 0x00006576, 0x00080004, 0x475f4c47, 0x4c474f4f,
+    0x6e695f45, 0x64756c63, 0x69645f65, 0x74636572, 0x00657669, 0x00040005,
+    0x00000004, 0x6e69616d, 0x00000000, 0x00050005, 0x00000009, 0x4374756f,
+    0x726f6c6f, 0x00000000, 0x00050005, 0x0000000c, 0x67617266, 0x6f6c6f43,
+    0x00000072, 0x00040047, 0x00000009, 0x0000001e, 0x00000000, 0x00040047,
+    0x0000000c, 0x0000001e, 0x00000000, 0x00020013, 0x00000002, 0x00030021,
+    0x00000003, 0x00000002, 0x00030016, 0x00000006, 0x00000020, 0x00040017,
+    0x00000007, 0x00000006, 0x00000004, 0x00040020, 0x00000008, 0x00000003,
+    0x00000007, 0x0004003b, 0x00000008, 0x00000009, 0x00000003, 0x00040017,
+    0x0000000a, 0x00000006, 0x00000003, 0x00040020, 0x0000000b, 0x00000001,
+    0x0000000a, 0x0004003b, 0x0000000b, 0x0000000c, 0x00000001, 0x0004002b,
+    0x00000006, 0x0000000e, 0x3f800000, 0x00050036, 0x00000002, 0x00000004,
+    0x00000000, 0x00000003, 0x000200f8, 0x00000005, 0x0004003d, 0x0000000a,
+    0x0000000d, 0x0000000c, 0x00050051, 0x00000006, 0x0000000f, 0x0000000d,
+    0x00000000, 0x00050051, 0x00000006, 0x00000010, 0x0000000d, 0x00000001,
+    0x00050051, 0x00000006, 0x00000011, 0x0000000d, 0x00000002, 0x00070050,
+    0x00000007, 0x00000012, 0x0000000f, 0x00000010, 0x00000011, 0x0000000e,
+    0x0003003e, 0x00000009, 0x00000012, 0x000100fd, 0x00010038,
+};
+
+}  // namespace sophia::shaders

engine/src/shaders/model_render_system.vert.spv.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+
+namespace sophia::shaders {
+
+inline constexpr std::array<uint32_t, 345> model_render_system_vert_spv = {
+    0x07230203, 0x00010000, 0x000d000b, 0x00000029, 0x00000000, 0x00020011,
+    0x00000001, 0x0006000b, 0x00000001, 0x4c534c47, 0x6474732e, 0x3035342e,
+    0x00000000, 0x0003000e, 0x00000000, 0x00000001, 0x0009000f, 0x00000000,
+    0x00000004, 0x6e69616d, 0x00000000, 0x0000000d, 0x00000019, 0x00000025,
+    0x00000027, 0x00030003, 0x00000002, 0x000001c2, 0x000a0004, 0x475f4c47,
+    0x4c474f4f, 0x70635f45, 0x74735f70, 0x5f656c79, 0x656e696c, 0x7269645f,
+    0x69746365, 0x00006576, 0x00080004, 0x475f4c47, 0x4c474f4f, 0x6e695f45,
+    0x64756c63, 0x69645f65, 0x74636572, 0x00657669, 0x00040005, 0x00000004,
+    0x6e69616d, 0x00000000, 0x00060005, 0x0000000b, 0x505f6c67, 0x65567265,
+    0x78657472, 0x00000000, 0x00060006, 0x0000000b, 0x00000000, 0x505f6c67,
+    0x7469736f, 0x006e6f69, 0x00070006, 0x0000000b, 0x00000001, 0x505f6c67,
+    0x746e696f, 0x657a6953, 0x00000000, 0x00070006, 0x0000000b, 0x00000002,
+    0x435f6c67, 0x4470696c, 0x61747369, 0x0065636e, 0x00070006, 0x0000000b,
+    0x00000003, 0x435f6c67, 0x446c6c75, 0x61747369, 0x0065636e, 0x00030005,
+    0x0000000d, 0x00000000, 0x00040005, 0x00000011, 0x68737550, 0x00000000,
+    0x00060006, 0x00000011, 0x00000000, 0x6e617274, 0x726f6673, 0x0000006d,
+    0x00050006, 0x00000011, 0x00000001, 0x6f6c6f63, 0x00000072, 0x00040005,
+    0x00000013, 0x68737570, 0x00000000, 0x00050005, 0x00000019, 0x69736f70,
+    0x6e6f6974, 0x00000000, 0x00050005, 0x00000025, 0x67617266, 0x6f6c6f43,
+    0x00000072, 0x00040005, 0x00000027, 0x6f6c6f63, 0x00000072, 0x00030047,
+    0x0000000b, 0x00000002, 0x00050048, 0x0000000b, 0x00000000, 0x0000000b,
+    0x00000000, 0x00050048, 0x0000000b, 0x00000001, 0x0000000b, 0x00000001,
+    0x00050048, 0x0000000b, 0x00000002, 0x0000000b, 0x00000003, 0x00050048,
+    0x0000000b, 0x00000003, 0x0000000b, 0x00000004, 0x00030047, 0x00000011,
+    0x00000002, 0x00040048, 0x00000011, 0x00000000, 0x00000005, 0x00050048,
+    0x00000011, 0x00000000, 0x00000007, 0x00000010, 0x00050048, 0x00000011,
+    0x00000000, 0x00000023, 0x00000000, 0x00050048, 0x00000011, 0x00000001,
+    0x00000023, 0x00000040, 0x00040047, 0x00000019, 0x0000001e, 0x00000000,
+    0x00040047, 0x00000025, 0x0000001e, 0x00000000, 0x00040047, 0x00000027,
+    0x0000001e, 0x00000001, 0x00020013, 0x00000002, 0x00030021, 0x00000003,
+    0x00000002, 0x00030016, 0x00000006, 0x00000020, 0x00040017, 0x00000007,
+    0x00000006, 0x00000004, 0x00040015, 0x00000008, 0x00000020, 0x00000000,
+    0x0004002b, 0x00000008, 0x00000009, 0x00000001, 0x0004001c, 0x0000000a,
+    0x00000006, 0x00000009, 0x0006001e, 0x0000000b, 0x00000007, 0x00000006,
+    0x0000000a, 0x0000000a, 0x00040020, 0x0000000c, 0x00000003, 0x0000000b,
+    0x0004003b, 0x0000000c, 0x0000000d, 0x00000003, 0x00040015, 0x0000000e,
+    0x00000020, 0x00000001, 0x0004002b, 0x0000000e, 0x0000000f, 0x00000000,
+    0x00040018, 0x00000010, 0x00000007, 0x00000004, 0x0004001e, 0x00000011,
+    0x00000010, 0x00000007, 0x00040020, 0x00000012, 0x00000009, 0x00000011,
+    0x0004003b, 0x00000012, 0x00000013, 0x00000009, 0x00040020, 0x00000014,
+    0x00000009, 0x00000010, 0x00040017, 0x00000017, 0x00000006, 0x00000002,
+    0x00040020, 0x00000018, 0x00000001, 0x00000017, 0x0004003b, 0x00000018,
+    0x00000019, 0x00000001, 0x0004002b, 0x00000006, 0x0000001b, 0x00000000,
+    0x0004002b, 0x00000006, 0x0000001c, 0x3f800000, 0x00040020, 0x00000021,
+    0x00000003, 0x00000007, 0x00040017, 0x00000023, 0x00000006, 0x00000003,
+    0x00040020, 0x00000024, 0x00000003, 0x00000023, 0x0004003b, 0x00000024,
+    0x00000025, 0x00000003, 0x00040020, 0x00000026, 0x00000001, 0x00000023,
+    0x0004003b, 0x00000026, 0x00000027, 0x00000001, 0x00050036, 0x00000002,
+    0x00000004, 0x00000000, 0x00000003, 0x000200f8, 0x00000005, 0x00050041,
+    0x00000014, 0x00000015, 0x00000013, 0x0000000f, 0x0004003d, 0x00000010,
+    0x00000016, 0x00000015, 0x0004003d, 0x00000017, 0x0000001a, 0x00000019,
+    0x00050051, 0x00000006, 0x0000001d, 0x0000001a, 0x00000000, 0x00050051,
+    0x00000006, 0x0000001e, 0x0000001a, 0x00000001, 0x00070050, 0x00000007,
+    0x0000001f, 0x0000001d, 0x0000001e, 0x0000001b, 0x0000001c, 0x00050091,
+    0x00000007, 0x00000020, 0x00000016, 0x0000001f, 0x00050041, 0x00000021,
+    0x00000022, 0x0000000d, 0x0000000f, 0x0003003e, 0x00000022, 0x00000020,
+    0x0004003d, 0x00000023, 0x00000028, 0x00000027, 0x0003003e, 0x00000025,
+    0x00000028, 0x000100fd, 0x00010038,
+};
+
+}  // namespace sophia::shaders

engine/src/ui/debug_ui.cpp

@@ -12,6 +12,7 @@ DebugUI::DebugUI(PanelRegistry& registry, ConsoleCommandRegistry& commands)
   this->panelRegistryHandle = registry.emplace<PanelRegistryPanel>(registry);
   this->frameStatsHandle = registry.emplace<FrameStatsPanel>();
   this->consoleHandle = registry.emplace<ConsolePanel>(commands);
+  hide();
   // #endif  // !NDEBUG
 }
 

engine/src/ui/panel_registry.cpp

@@ -1,88 +1,23 @@
 #include <sophia/ui/panel_registry.hpp>
-#include <sophia/util/assert.hpp>
 
 namespace sophia {
 
-namespace {
-constexpr u32 GENERATION_MASK = (1u << 12) - 1;
-}  // namespace
-
-PanelHandle PanelRegistry::add(std::unique_ptr<Panel> panel) {
-  if (!freeList.empty()) {
-    u32 index = freeList.back();
-    freeList.pop_back();
-    slots[index].panel = std::move(panel);
-    return PanelHandle{index, slots[index].generation};
-  }
-
-  slots.push_back(Slot{std::move(panel), 0});
-  return PanelHandle{static_cast<u32>(slots.size() - 1), 0};
-}
-
-const Panel& PanelRegistry::get(PanelHandle handle) const {
-  SOPHIA_ASSERT(handle.isValid(), "invalid PanelHandle");
-  SOPHIA_ASSERT(handle.index < slots.size(),
-                "PanelHandle index out of range:", handle.index);
-
-  const Slot& slot = slots[handle.index];
-  SOPHIA_ASSERT(slot.generation == handle.generation,
-                "stale PanelHandle (generation mismatch):", handle.index);
-  SOPHIA_ASSERT(slot.panel != nullptr,
-                "PanelHandle refers to a removed panel:", handle.index);
-  return *slot.panel;
-}
-
-void PanelRegistry::remove(PanelHandle handle) {
-  SOPHIA_ASSERT(handle.isValid(), "invalid PanelHandle");
-  SOPHIA_ASSERT(handle.index < slots.size(),
-                "PanelHandle index out of range:", handle.index);
-
-  Slot& slot = slots[handle.index];
-  SOPHIA_ASSERT(slot.generation == handle.generation,
-                "stale PanelHandle (generation mismatch):", handle.index);
-  SOPHIA_ASSERT(slot.panel != nullptr,
-                "PanelHandle already removed:", handle.index);
-
-  slot.panel.reset();
-  slot.generation = (slot.generation + 1) & GENERATION_MASK;
-  freeList.push_back(handle.index);
-}
-
-bool PanelRegistry::isValid(PanelHandle handle) const {
-  if (!handle.isValid() || handle.index >= slots.size()) {
-    return false;
-  }
-
-  const Slot& slot = slots[handle.index];
-  return slot.generation == handle.generation && slot.panel != nullptr;
-}
-
-u32 PanelRegistry::size() const {
-  u32 count = 0;
-  for (const Slot& slot : slots) {
-    if (slot.panel) {
-      count++;
-    }
-  }
-  return count;
-}
-
 u32 PanelRegistry::visibleCount() const {
   u32 count = 0;
-  for (const Slot& slot : slots) {
-    if (slot.panel && slot.panel->isVisible()) {
+  pool.forEach([&count](const Panel& panel) {
+    if (panel.isVisible()) {
       count++;
     }
-  }
+  });
   return count;
 }
 
 void PanelRegistry::update(const FrameInfo& frameInfo) {
-  for (auto& slot : slots) {
-    if (slot.panel && slot.panel->isVisible()) {
-      slot.panel->draw(frameInfo);
-    }
+  pool.forEach([&frameInfo](Panel& panel) {
+    if (panel.isVisible()) {
+      panel.draw(frameInfo);
     }
+  });
 }
 
 }  // namespace sophia

engine/src/ui/ui.cpp

@@ -0,0 +1,26 @@
+#include <sophia/ui/ui.hpp>
+#include <sophia/util/assert.hpp>
+
+#include "rendering/imgui_renderer.hpp"
+
+namespace sophia {
+
+void UI::image(RenderTargetHandle handle) {
+  const ImVec2 size = ImGui::GetContentRegionAvail();
+  if (size.x < 1.0f || size.y < 1.0f) {
+    return;
+  }
+
+  resources.requestResize(handle, static_cast<u32>(size.x),
+                          static_cast<u32>(size.y));
+  ImTextureID textureId = getTextureId(handle);
+  ImGui::Image(textureId, size);
+}
+
+ImTextureID UI::getTextureId(RenderTargetHandle handle) {
+  SOPHIA_ASSERT(renderer != nullptr,
+                "UI::getTextureId() called before the UI was set up");
+  return renderer->getTextureId(handle);
+}
+
+}  // namespace sophia

engine/src/vulkan/access.cpp

@@ -0,0 +1,104 @@
+#include "vulkan/access.hpp"
+
+#include <array>
+#include <sophia/util/logger.hpp>
+#include <stdexcept>
+
+namespace sophia {
+
+namespace {
+
+constexpr std::array<Access, 7> ALL_ACCESSES = {
+    Access::ColorWrite,       Access::DepthWrite,  Access::SampledRead,
+    Access::StorageReadWrite, Access::TransferSrc, Access::TransferDst,
+    Access::Present,
+};
+
+constexpr vk::AccessFlags WRITE_ACCESSES =
+    vk::AccessFlagBits::eColorAttachmentWrite |
+    vk::AccessFlagBits::eDepthStencilAttachmentWrite |
+    vk::AccessFlagBits::eShaderWrite | vk::AccessFlagBits::eTransferWrite;
+
+}  // namespace
+
+AccessState getAccessState(Access access) {
+  switch (access) {
+    case Access::ColorWrite:
+      return {vk::ImageLayout::eColorAttachmentOptimal,
+              vk::PipelineStageFlagBits::eColorAttachmentOutput,
+              vk::AccessFlagBits::eColorAttachmentRead |
+                  vk::AccessFlagBits::eColorAttachmentWrite};
+    case Access::DepthWrite:
+      return {vk::ImageLayout::eDepthStencilAttachmentOptimal,
+              vk::PipelineStageFlagBits::eEarlyFragmentTests |
+                  vk::PipelineStageFlagBits::eLateFragmentTests,
+              vk::AccessFlagBits::eDepthStencilAttachmentRead |
+                  vk::AccessFlagBits::eDepthStencilAttachmentWrite};
+    case Access::SampledRead:
+      return {vk::ImageLayout::eShaderReadOnlyOptimal,
+              vk::PipelineStageFlagBits::eFragmentShader,
+              vk::AccessFlagBits::eShaderRead};
+    case Access::StorageReadWrite:
+      return {
+          vk::ImageLayout::eGeneral, vk::PipelineStageFlagBits::eComputeShader,
+          vk::AccessFlagBits::eShaderRead | vk::AccessFlagBits::eShaderWrite};
+    case Access::TransferSrc:
+      return {vk::ImageLayout::eTransferSrcOptimal,
+              vk::PipelineStageFlagBits::eTransfer,
+              vk::AccessFlagBits::eTransferRead};
+    case Access::TransferDst:
+      return {vk::ImageLayout::eTransferDstOptimal,
+              vk::PipelineStageFlagBits::eTransfer,
+              vk::AccessFlagBits::eTransferWrite};
+    case Access::Present:
+      return {vk::ImageLayout::ePresentSrcKHR,
+              vk::PipelineStageFlagBits::eBottomOfPipe, vk::AccessFlags{}};
+  }
+
+  log::fatal("Unknown Access value.");
+  throw std::runtime_error("Unknown Access value.");
+}
+
+AccessState getStateForLayout(vk::ImageLayout layout) {
+  if (layout == vk::ImageLayout::eUndefined) {
+    return AccessState{};
+  }
+
+  for (Access access : ALL_ACCESSES) {
+    AccessState state = getAccessState(access);
+    if (state.layout == layout) {
+      return state;
+    }
+  }
+
+  log::fatal("Unsupported image layout:", vk::to_string(layout));
+  throw std::runtime_error("Unsupported image layout.");
+}
+
+bool writesImage(const AccessState& state) {
+  return static_cast<bool>(state.access & WRITE_ACCESSES);
+}
+
+bool needsBarrier(const AccessState& from, const AccessState& to) {
+  return from.layout != to.layout || writesImage(from) || writesImage(to);
+}
+
+vk::ImageMemoryBarrier makeImageBarrier(vk::Image image,
+                                        const vk::ImageSubresourceRange& range,
+                                        const AccessState& from,
+                                        const AccessState& to) {
+  vk::ImageMemoryBarrier barrier{};
+  barrier.oldLayout = from.layout;
+  barrier.newLayout = to.layout;
+  barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
+  barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
+  barrier.image = image;
+  barrier.subresourceRange = range;
+  // Only writes need to be made available; reads just need the execution
+  // dependency the stage masks already give.
+  barrier.srcAccessMask = from.access & WRITE_ACCESSES;
+  barrier.dstAccessMask = to.access;
+  return barrier;
+}
+
+}  // namespace sophia

engine/src/vulkan/access.hpp

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <vulkan/vulkan.hpp>
+
+namespace sophia {
+
+/**
+ * How an image is used at a point in a frame. Each value implies an image
+ * layout plus the pipeline stages and memory accesses that go with it, so a
+ * barrier between any two of them can be derived instead of hand-written.
+ */
+enum class Access {
+  ColorWrite,
+  DepthWrite,
+  SampledRead,
+  StorageReadWrite,
+  TransferSrc,
+  TransferDst,
+  Present,
+};
+
+/**
+ * The layout, stages and accesses an image is in after some use. Barriers go
+ * from one of these to another.
+ */
+struct AccessState {
+  vk::ImageLayout layout = vk::ImageLayout::eUndefined;
+  vk::PipelineStageFlags stage = vk::PipelineStageFlagBits::eTopOfPipe;
+  vk::AccessFlags access;
+};
+
+/**
+ * The stage RenderContext waits on for the swapchain image-available
+ * semaphore. A barrier that takes a swapchain image out of its
+ * just-acquired state has to use this as its source stage, otherwise the
+ * layout transition isn't ordered after the acquire.
+ */
+inline constexpr vk::PipelineStageFlags SWAPCHAIN_ACQUIRE_STAGE =
+    vk::PipelineStageFlagBits::eColorAttachmentOutput;
+
+AccessState getAccessState(Access access);
+
+/**
+ * The state of an image sitting in `layout` with no outstanding work.
+ * eUndefined maps to "nothing to wait on"; layouts with no matching Access
+ * throw.
+ */
+AccessState getStateForLayout(vk::ImageLayout layout);
+
+bool writesImage(const AccessState& state);
+
+/**
+ * Whether going from `from` to `to` needs a barrier: a layout change, or any
+ * hazard involving a write. Read-after-read in the same layout doesn't.
+ */
+bool needsBarrier(const AccessState& from, const AccessState& to);
+
+vk::ImageMemoryBarrier makeImageBarrier(vk::Image image,
+                                        const vk::ImageSubresourceRange& range,
+                                        const AccessState& from,
+                                        const AccessState& to);
+
+}  // namespace sophia

engine/src/vulkan/buffer.cpp

@@ -2,7 +2,7 @@
  * Based on
  * https://github.com/blurrypiano/littleVulkanEngine/blob/main/src/lve_buffer.cpp
  */
-#include "buffer.hpp"
+#include "vulkan/buffer.hpp"
 
 #include <sophia/util/assert.hpp>
 

engine/src/vulkan/buffer.hpp

@@ -4,7 +4,7 @@
  */
 #pragma once
 
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 

engine/src/vulkan/debug_label.cpp

@@ -0,0 +1,34 @@
+#include "vulkan/debug_label.hpp"
+
+namespace sophia {
+
+static PFN_vkCmdBeginDebugUtilsLabelEXT cmdBeginDebugUtilsLabel = nullptr;
+static PFN_vkCmdEndDebugUtilsLabelEXT cmdEndDebugUtilsLabel = nullptr;
+
+void loadDebugLabelFunctions(vk::Instance instance) {
+  cmdBeginDebugUtilsLabel = reinterpret_cast<PFN_vkCmdBeginDebugUtilsLabelEXT>(
+      vkGetInstanceProcAddr(instance, "vkCmdBeginDebugUtilsLabelEXT"));
+  cmdEndDebugUtilsLabel = reinterpret_cast<PFN_vkCmdEndDebugUtilsLabelEXT>(
+      vkGetInstanceProcAddr(instance, "vkCmdEndDebugUtilsLabelEXT"));
+}
+
+void beginDebugLabel(vk::CommandBuffer commandBuffer, const char* name) {
+  if (!cmdBeginDebugUtilsLabel) {
+    return;
+  }
+
+  VkDebugUtilsLabelEXT label{};
+  label.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT;
+  label.pLabelName = name;
+  cmdBeginDebugUtilsLabel(commandBuffer, &label);
+}
+
+void endDebugLabel(vk::CommandBuffer commandBuffer) {
+  if (!cmdEndDebugUtilsLabel) {
+    return;
+  }
+
+  cmdEndDebugUtilsLabel(commandBuffer);
+}
+
+}  // namespace sophia

engine/src/vulkan/debug_label.hpp

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <vulkan/vulkan.hpp>
+
+namespace sophia {
+
+void loadDebugLabelFunctions(vk::Instance instance);
+
+void beginDebugLabel(vk::CommandBuffer commandBuffer, const char* name);
+
+void endDebugLabel(vk::CommandBuffer commandBuffer);
+
+}  // namespace sophia

engine/src/vulkan/descriptors/descriptor_pool.hpp

@@ -3,7 +3,7 @@
 #include <memory>
 #include <vector>
 
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 

engine/src/vulkan/descriptors/descriptor_set_layout.hpp

@@ -4,7 +4,7 @@
 #include <unordered_map>
 #include <vector>
 
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 

engine/src/vulkan/descriptors/descriptor_writer.hpp

@@ -4,7 +4,7 @@
 
 #include "descriptor_pool.hpp"
 #include "descriptor_set_layout.hpp"
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 

engine/src/vulkan/device.cpp

@@ -1,10 +1,12 @@
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 #include <string.h>
 
 #include <set>
 #include <sophia/util/logger.hpp>
 
+#include "vulkan/debug_label.hpp"
+
 namespace sophia {
 
 static VKAPI_ATTR vk::Bool32 VKAPI_CALL
@@ -288,6 +290,8 @@ void Device::setupDebugMessenger() {
           nullptr, &this->debugMessenger) != VK_SUCCESS) {
     throw std::runtime_error("failed to set up debug callback!");
   }
+
+  loadDebugLabelFunctions(*instance);
 }
 
 bool Device::checkValidationLayerSupport() {

engine/src/vulkan/image.cpp

@@ -1,81 +1,42 @@
-#include "image.hpp"
+#include "vulkan/image.hpp"
 
 #include <cstring>
 #include <sophia/util/logger.hpp>
 #include <stdexcept>
 
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 
-void Image::transitionLayout(vk::CommandBuffer commandBuffer,
-                             vk::ImageLayout newLayout) {
-  vk::ImageMemoryBarrier barrier{};
-  barrier.oldLayout = this->layout;
-  barrier.newLayout = newLayout;
-  barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
-  barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
-  barrier.image = this->get();
-  barrier.subresourceRange.aspectMask = this->aspectMask;
-  barrier.subresourceRange.baseMipLevel = 0;
-  barrier.subresourceRange.levelCount = this->mipLevels;
-  barrier.subresourceRange.baseArrayLayer = 0;
-  barrier.subresourceRange.layerCount = this->arrayLayers;
-
-  vk::PipelineStageFlags srcStage;
-  vk::PipelineStageFlags dstStage;
-
-  if (this->layout == vk::ImageLayout::eUndefined &&
-      newLayout == vk::ImageLayout::eTransferDstOptimal) {
-    barrier.srcAccessMask = {};
-    barrier.dstAccessMask = vk::AccessFlagBits::eTransferWrite;
-    srcStage = vk::PipelineStageFlagBits::eTopOfPipe;
-    dstStage = vk::PipelineStageFlagBits::eTransfer;
-  } else if (this->layout == vk::ImageLayout::eTransferDstOptimal &&
-             newLayout == vk::ImageLayout::eShaderReadOnlyOptimal) {
-    barrier.srcAccessMask = vk::AccessFlagBits::eTransferWrite;
-    barrier.dstAccessMask = vk::AccessFlagBits::eShaderRead;
-    srcStage = vk::PipelineStageFlagBits::eTransfer;
-    dstStage = vk::PipelineStageFlagBits::eFragmentShader;
-  } else if (this->layout == vk::ImageLayout::eUndefined &&
-             newLayout == vk::ImageLayout::eDepthStencilAttachmentOptimal) {
-    barrier.srcAccessMask = {};
-    barrier.dstAccessMask = vk::AccessFlagBits::eDepthStencilAttachmentRead |
-                            vk::AccessFlagBits::eDepthStencilAttachmentWrite;
-    srcStage = vk::PipelineStageFlagBits::eTopOfPipe;
-    dstStage = vk::PipelineStageFlagBits::eEarlyFragmentTests;
-  } else if (this->layout == vk::ImageLayout::eUndefined &&
-             newLayout == vk::ImageLayout::eColorAttachmentOptimal) {
-    barrier.srcAccessMask = {};
-    barrier.dstAccessMask = vk::AccessFlagBits::eColorAttachmentWrite;
-    srcStage = vk::PipelineStageFlagBits::eTopOfPipe;
-    dstStage = vk::PipelineStageFlagBits::eColorAttachmentOutput;
-  } else if (this->layout == vk::ImageLayout::eUndefined &&
-             newLayout == vk::ImageLayout::eGeneral) {
-    barrier.srcAccessMask = {};
-    barrier.dstAccessMask =
-        vk::AccessFlagBits::eShaderRead | vk::AccessFlagBits::eShaderWrite;
-    srcStage = vk::PipelineStageFlagBits::eTopOfPipe;
-    dstStage = vk::PipelineStageFlagBits::eComputeShader;
-  } else if (this->layout == vk::ImageLayout::eColorAttachmentOptimal &&
-             newLayout == vk::ImageLayout::ePresentSrcKHR) {
-    barrier.srcAccessMask = vk::AccessFlagBits::eColorAttachmentWrite;
-    barrier.dstAccessMask = {};
-    srcStage = vk::PipelineStageFlagBits::eColorAttachmentOutput;
-    dstStage = vk::PipelineStageFlagBits::eBottomOfPipe;
-  } else if (this->layout == vk::ImageLayout::ePresentSrcKHR &&
-             newLayout == vk::ImageLayout::eColorAttachmentOptimal) {
-    barrier.srcAccessMask = {};
-    barrier.dstAccessMask = vk::AccessFlagBits::eColorAttachmentWrite;
-    srcStage = vk::PipelineStageFlagBits::eTopOfPipe;
-    dstStage = vk::PipelineStageFlagBits::eColorAttachmentOutput;
-  } else {
-    log::fatal("Unsupported image layout transition.");
-    throw std::runtime_error("Unsupported image layout transition.");
+vk::ImageSubresourceRange Image::getSubresourceRange() const {
+  return vk::ImageSubresourceRange{this->aspectMask, 0, this->mipLevels, 0,
+                                   this->arrayLayers};
 }
 
-  commandBuffer.pipelineBarrier(srcStage, dstStage, {}, nullptr, nullptr,
+AccessState Image::getAccessState() const {
+  AccessState state = getStateForLayout(this->layout);
+
+  // A wrapped (swapchain) image is handed to us by the acquire semaphore, so
+  // whatever we do next has to be ordered after that wait.
+  if (this->isExternal() && (this->layout == vk::ImageLayout::eUndefined ||
+                             this->layout == vk::ImageLayout::ePresentSrcKHR)) {
+    state.stage = SWAPCHAIN_ACQUIRE_STAGE;
+  }
+
+  return state;
+}
+
+void Image::transitionLayout(vk::CommandBuffer commandBuffer,
+                             vk::ImageLayout newLayout) {
+  AccessState from = this->getAccessState();
+  AccessState to = getStateForLayout(newLayout);
+
+  if (needsBarrier(from, to)) {
+    vk::ImageMemoryBarrier barrier =
+        makeImageBarrier(this->get(), this->getSubresourceRange(), from, to);
+    commandBuffer.pipelineBarrier(from.stage, to.stage, {}, nullptr, nullptr,
                                   barrier);
+  }
 
   this->layout = newLayout;
 }

engine/src/vulkan/image.hpp

@@ -4,6 +4,8 @@
 #include <sophia/types.hpp>
 #include <vulkan/vulkan.hpp>
 
+#include "vulkan/access.hpp"
+
 namespace sophia {
 
 class Device;
@@ -28,6 +30,20 @@ class Image {
   vk::Format getFormat() const { return this->format; }
   vk::Extent3D getExtent() const { return this->extent; }
   vk::ImageLayout getLayout() const { return this->layout; }
+  vk::ImageSubresourceRange getSubresourceRange() const;
+
+  /**
+   * The layout this image was last left in, plus the stages and accesses that
+   * a barrier out of it has to wait on.
+   */
+  AccessState getAccessState() const;
+
+  /**
+   * Updates the tracked layout without recording a barrier. For code that
+   * does its own transitions (the RenderGraph) and needs to hand the final
+   * layout back.
+   */
+  void recordLayout(vk::ImageLayout newLayout) { this->layout = newLayout; }
 
   void transitionLayout(vk::CommandBuffer commandBuffer,
                         vk::ImageLayout newLayout);

engine/src/vulkan/pipelines/compute_pipeline.hpp

@@ -3,9 +3,9 @@
 #include <memory>
 #include <vulkan/vulkan.hpp>
 
-#include "device.hpp"
 #include "pipeline.hpp"
-#include "shader.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/shader.hpp"
 
 namespace sophia {
 

engine/src/vulkan/pipelines/graphics_pipeline.hpp

@@ -6,9 +6,9 @@
 #include <vector>
 #include <vulkan/vulkan.hpp>
 
-#include "device.hpp"
 #include "pipeline.hpp"
-#include "shader.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/shader.hpp"
 
 namespace sophia {
 

engine/src/vulkan/pipelines/pipeline.hpp

@@ -4,7 +4,7 @@
 #include <vector>
 #include <vulkan/vulkan.hpp>
 
-#include "device.hpp"
+#include "vulkan/device.hpp"
 
 namespace sophia {
 

engine/src/vulkan/shader.cpp

@@ -1,4 +1,4 @@
-#include "shader.hpp"
+#include "vulkan/shader.hpp"
 
 #include <fstream>
 #include <shaderc/shaderc.hpp>
@@ -74,8 +74,7 @@ void Shader::load(const std::string& path, ShaderStage shaderStage) {
     throw std::runtime_error("invalid SPIR-V binary: " + path);
   }
 
-  this->spirv.assign(
-      reinterpret_cast<const u32*>(bytes.data()),
+  this->spirv.assign(reinterpret_cast<const u32*>(bytes.data()),
                      reinterpret_cast<const u32*>(bytes.data() + bytes.size()));
 
   log::info("Loaded precompiled shader: " + path + " (" +

engine/src/vulkan/swapchain.cpp

@@ -1,4 +1,4 @@
-#include "swapchain.hpp"
+#include "vulkan/swapchain.hpp"
 
 #include <algorithm>
 #include <limits>

engine/src/vulkan/swapchain.hpp

@@ -5,8 +5,8 @@
 #include <vector>
 #include <vulkan/vulkan.hpp>
 
-#include "device.hpp"
-#include "image.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/image.hpp"
 
 namespace sophia {
 
@@ -23,9 +23,6 @@ class Swapchain {
   Image& getImage(int index) const { return *this->images.at(index); }
   Image& getDepthImage(int index) const { return *this->depthImages.at(index); }
 
-  vk::ImageView getImageView(int index) const {
-    return this->images.at(index)->getView();
-  }
   vk::ImageView getDepthImageView(int index) const {
     return this->depthImages.at(index)->getView();
   }

examples/boids_2d/main.cpp

@@ -1,6 +1,9 @@
 #include <algorithm>
 #include <cmath>
 #include <cstdint>
+#include <glm/glm.hpp>
+#include <glm/gtc/constants.hpp>
+#include <glm/gtc/matrix_transform.hpp>
 #include <iostream>
 #include <random>
 #include <sophia/application.hpp>
@@ -10,12 +13,6 @@
 #include <string>
 #include <vector>
 
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-#include <glm/gtc/constants.hpp>
-#include <glm/gtc/matrix_transform.hpp>
-
 struct Boid {
   glm::vec2 position;
   glm::vec2 velocity;
@@ -91,7 +88,7 @@ class Boids2D : public sophia::Application {
         {{-BOID_LENGTH * 0.5f, BOID_WIDTH * 0.5f}, {1.0f, 1.0f, 1.0f}},
         {{-BOID_LENGTH * 0.5f, -BOID_WIDTH * 0.5f}, {1.0f, 1.0f, 1.0f}},
     };
-    boidMesh = assets().loadMesh(std::move(vertices), {});
+    boidMesh = resources().create<sophia::Mesh>(std::move(vertices));
   }
 
   void onUpdate(const sophia::FrameInfo& frameInfo) override {

testbed/main.cpp

@@ -1,17 +1,41 @@
-#include <iostream>
+#include <imgui.h>
+
 #include <sophia/application.hpp>
+#include <sophia/entity.hpp>
+#include <sophia/frame_info.hpp>
+#include <sophia/scene_view.hpp>
+#include <sophia/ui/panel.hpp>
+
+class Viewport : public sophia::Panel {
+ public:
+  Viewport(sophia::UI& ui, sophia::RenderTargetHandle target)
+      : Panel{{.name = "Viewport"}}, ui{ui}, target{target} {}
+
+  void onUpdate(const sophia::FrameInfo&) override {
+    ImGui::Text("Test ViewPort");
+
+    ui.image(target);
+  }
+
+ private:
+  sophia::UI& ui;
+  sophia::RenderTargetHandle target;
+};
 
 class Testbed : public sophia::Application {
  public:
   Testbed() : Application{{.width = 750, .height = 1000, .name = "Testbed"}} {}
 
   void onCreate() override {
-    std::cout << "Testbed created" << std::endl;
+    view = views().create({.scene = scenes().create(),
+                           .target = resources().create<sophia::RenderTarget>(),
+                           .clearColor = {0.1f, 0.1f, 0.15f, 1.f}});
 
-    debugUI().show();
+    panels().emplace<Viewport>(ui(), views().get(view).target);
   }
 
-  void onUpdate(const sophia::FrameInfo& frameInfo) override {}
+ private:
+  sophia::SceneViewHandle view;
 };
 
 SOPHIA_MAIN(Testbed)