Merge pull request 'Huge changes' (#3) from dev into main

Reviewed-on: #3

_Design/glossary.md

@@ -0,0 +1,329 @@
+# Glossary
+
+## AssetRegistry
+
+An AssetRegistry owns GPU-backed assets on the caller's behalf and hands out
+lightweight Handles instead of pointers or ownership.
+
+Internally it's a collection of per-type pools, each responsible for one
+asset type:
+
+```
+AssetRegistry
+ ├── MeshPool     → MeshHandle
+ ├── TexturePool  → TextureHandle   (planned)
+ └── MaterialPool → MaterialHandle  (planned)
+```
+
+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).
+
+Typical lifecycle:
+
+```
+load<Mesh>(path) / loadMesh(...)  →  MeshHandle
+                                        │
+                        get<Mesh>(handle)  →  const Mesh&
+                                        │
+                        release<Mesh>(handle)
+```
+
+Think: "Where do I get or release a GPU asset by handle, without owning its
+lifetime directly?"
+
+## Buffer
+
+A Buffer is a linear region of GPU memory used to store arbitrary data.
+
+Unlike an Image, which is designed for multidimensional image data, a buffer is essentially:
+
+```
+[ byte byte byte byte byte byte ... ]
+```
+
+Buffers commonly contain:
+
+Vertex data
+Index data
+Uniform data
+Storage data
+Indirect draw commands
+
+For example:
+
+```
+Vertex Buffer
+┌─────────────────────────────────┐
+│ Vertex │ Vertex │ Vertex │ ...  │
+└─────────────────────────────────┘
+```
+
+In Vulkan, VkBuffer / vk::Buffer is a fundamental resource.
+
+Think: "A linear chunk of GPU-accessible data."
+
+## Camera
+
+A Camera defines how the scene is viewed and projected onto the screen.
+
+It generally contains:
+
+Position
+Orientation
+Projection parameters
+View matrix
+Projection matrix
+
+For example:
+
+```
+Camera
+ ├── Position
+ ├── Rotation
+ ├── Projection
+ │    ├── Perspective
+ │    └── Orthographic
+ ├── View Matrix
+ └── Projection Matrix
+```
+
+Think: "From where and how am I looking at the scene?"
+
+## Canvas
+
+A Canvas is a coordinate/rendering space onto which things are drawn.
+
+For UI, for example:
+
+```
+Canvas
+┌──────────────────────────────┐
+│                              │
+│    ┌──────────────┐          │
+│    │ Panel        │          │
+│    └──────────────┘          │
+│                              │
+│              Button          │
+│                              │
+└──────────────────────────────┘
+```
+
+A canvas establishes things such as:
+
+Dimensions
+Coordinate system
+Origin
+Scaling
+Potentially clipping
+
+In a UI system, a Canvas is essentially:
+
+The space in which UI elements are laid out and rendered.
+
+## Frame
+
+Frame is context-dependent, but in a renderer it usually means one iteration of rendering the scene to produce one displayed image.
+
+## Layer
+
+A Layer is a logical ordering/grouping of content.
+
+For example:
+
+Layer 0: Background
+Layer 1: World
+Layer 2: Characters
+Layer 3: Effects
+Layer 4: UI
+
+Higher layers can be rendered over lower layers.
+
+In a 2D engine, layers might determine draw order:
+
+```
+Background
+    ↓
+Tiles
+    ↓
+Player
+    ↓
+Particles
+    ↓
+UI
+```
+
+However, Layer is very engine-specific. In a 3D renderer it could instead represent a rendering category, visibility mask, or render-pass grouping.
+
+## Material
+
+A Material describes how a surface should be rendered.
+
+It usually combines:
+
+Shader/pipeline configuration
+Textures
+Colors
+Numerical parameters
+
+For example:
+
+```
+Material
+ ├── Shader
+ ├── Albedo Texture
+ ├── Normal Texture
+ ├── Roughness
+ ├── Metallic
+ └── Base Color
+```
+
+Then:
+
+```
+Mesh + Material + Transform
+              ↓
+           Renderer
+              ↓
+             GPU
+```
+
+A useful conceptual distinction is:
+
+Mesh = what the object is shaped like.
+Material = how that shape should look.
+
+## Mesh
+
+A Mesh is the geometric data used to describe the shape of an object.
+
+Typically contains:
+
+Vertex positions
+Normals
+Texture coordinates (UVs)
+Tangents
+Indices
+
+For example, a cube mesh contains the vertices and triangles necessary to describe a cube.
+
+```
+Mesh
+ ├── Vertices
+ ├── Indices
+ └── Vertex attributes
+      ├── Position
+      ├── Normal
+      ├── UV
+      └── Tangent
+```
+
+Think: "What shape is this object?"
+
+## Panel
+
+A Panel is a rectangular UI region/container.
+
+For example:
+
+```
+┌──────────────────────────────┐
+│ Toolbar                      │
+├───────────┬──────────────────┤
+│           │                  │
+│ Scene     │    Viewport      │
+│           │                  │
+├───────────┼──────────────────┤
+│ Inspector │ Console          │
+└───────────┴──────────────────┘
+```
+
+Each of those regions could be a panel.
+
+A panel generally has:
+
+Position
+Size
+Child elements
+UI contents
+Potentially its own rendering/context
+
+This is primarily a UI concept, rather than a GPU concept.
+
+## PanelRegistry
+
+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:
+
+```
+PanelRegistry
+ └── Slot { Panel, generation }  →  PanelHandle
+```
+
+Typical lifecycle:
+
+```
+add(panel) / emplace<T>(...)  →  PanelHandle
+                                        │
+                        get(handle) / get<T>(handle)  →  Panel& / T&
+                                        │
+                        remove(handle)
+```
+
+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?"
+
+## Sprite
+
+A Sprite is a 2D renderable representation of an image, usually a rectangular region of a texture.
+
+For example:
+
+```
+Texture Atlas
+┌─────────────────────┐
+│ Player │ Enemy      │
+│        │            │
+├────────┼────────────┤
+│ Tree   │ Rock       │
+└─────────────────────┘
+```
+
+A sprite might reference only the Player region of that texture.
+
+A useful engine abstraction might be:
+
+```cpp
+Sprite {
+    Texture* texture;
+    Rect uv;
+}
+```
+
+Think: "Which 2D picture/region am I drawing?"
+
+## Texture
+
+A Texture is image data intended to be used by a shader.
+
+It can represent:
+
+Color/albedo
+Normal maps
+Roughness
+Metallic values
+Masks
+Height maps
+etc.
+
+A texture doesn't necessarily have to be displayed directly.
+
+Texture → Shader → Material/Object
+
+Think: "What image/data does the shader sample?"

engine/include/sophia/application.hpp

@@ -3,13 +3,20 @@
 #include <cstdlib>
 #include <iostream>
 #include <memory>
+#include <sophia/asset_registry.hpp>
 #include <sophia/camera_2d.hpp>
 #include <sophia/canvas.hpp>
 #include <sophia/frame_info.hpp>
 #include <sophia/types.hpp>
+#include <sophia/ui/debug_ui.hpp>
+#include <sophia/ui/panel_registry.hpp>
 #include <string>
 #include <vector>
 
+#define GLM_FORCE_RADIANS
+#define GLM_FORCE_DEPTH_ZERO_TO_ONE
+#include <glm/glm.hpp>
+
 namespace sophia {
 
 class Application {
@@ -23,7 +30,7 @@ class Application {
   Application(const Application&) = delete;
   Application& operator=(const Application&) = delete;
 
-  Application(const Config& config);
+  explicit Application(const Config& config);
   virtual ~Application();
 
   void run();
@@ -36,10 +43,17 @@ class Application {
   virtual void onRender() {}
   virtual void onDestroy() {}
 
+  AssetRegistry& assets() { return this->assetRegistry; }
+  PanelRegistry& panels() { return this->panelRegistry; }
+
+  DebugUI& debugUI() { return this->_debugUI; }
+
   Canvas canvas;
   Camera2D camera;
   std::vector<std::string> args;
 
+  void drawMesh(MeshHandle handle, const glm::mat4& transform);
+
  private:
   friend class Canvas;
 
@@ -48,6 +62,11 @@ class Application {
 
   class Impl;
   std::unique_ptr<Impl> impl;
+
+  AssetRegistry assetRegistry;
+  PanelRegistry panelRegistry;
+
+  DebugUI _debugUI;
 };
 
 }  // namespace sophia

engine/include/sophia/asset_registry.hpp

@@ -0,0 +1,64 @@
+#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/canvas.hpp

@@ -33,7 +33,7 @@ class Canvas {
  private:
   friend class Application;
 
-  Canvas(Application* application);
+  explicit Canvas(Application* application);
 
   class Impl;
   std::unique_ptr<Impl> impl;

engine/include/sophia/components.hpp

@@ -0,0 +1,37 @@
+#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>
+
+namespace sophia {
+
+struct TagComponent {
+  std::string tag;  // entt::hashed_string ?
+};
+
+struct TransformComponent {
+  glm::vec3 position{0.f, 0.f, 0.f};
+  glm::quat rotation{1.f, 0.f, 0.f, 0.f};
+  glm::vec3 scale{1.f, 1.f, 1.f};
+
+  glm::mat4 mat4() const {
+    return glm::translate(glm::mat4{1.f}, position) * glm::mat4_cast(rotation) *
+           glm::scale(glm::mat4{1.f}, scale);
+  }
+
+  glm::mat3 normalMatrix() const {
+    return glm::mat3{glm::transpose(glm::inverse(mat4()))};
+  }
+};
+
+struct MeshComponent {
+  MeshHandle handle;
+};
+
+}  // namespace sophia

engine/include/sophia/handles.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <compare>
+
+#include "sophia/types.hpp"
+
+namespace sophia {
+
+template <typename Tag>
+struct Handle {
+  static constexpr u32 INVALID_INDEX = (1u << 20) - 1;
+
+  u32 index : 20 = INVALID_INDEX;
+  u32 generation : 12 = 1;
+
+  [[nodiscard]] static constexpr Handle invalid() {
+    return Handle{INVALID_INDEX, 0};
+  }
+
+  [[nodiscard]] constexpr bool isValid() const {
+    return index != INVALID_INDEX;
+  }
+
+  [[nodiscard]] auto operator<=>(const Handle&) const = default;
+};
+
+struct MeshTag {};
+struct PanelTag {};
+
+using MeshHandle = Handle<MeshTag>;
+using PanelHandle = Handle<PanelTag>;
+
+}  // namespace sophia

engine/include/sophia/ui/debug_ui.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <sophia/handles.hpp>
+#include <sophia/ui/panel_registry.hpp>
+
+namespace sophia {
+
+class DebugUI {
+ public:
+  DebugUI(const DebugUI&) = delete;
+  DebugUI& operator=(const DebugUI&) = delete;
+
+  explicit DebugUI(PanelRegistry& registry);
+  ~DebugUI() = default;
+
+  void show();
+  void hide();
+
+  void showPanelRegistry(bool show = true);
+  void showFrameStats(bool show = true);
+  void showConsole(bool show = true);
+
+ private:
+  PanelRegistry& registry;
+
+  PanelHandle panelRegistryHandle;
+  PanelHandle frameStatsHandle;
+  PanelHandle consoleHandle;
+};
+
+}  // namespace sophia

engine/include/sophia/ui/panel.hpp

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <sophia/frame_info.hpp>
+#include <string>
+#include <utility>
+
+namespace sophia {
+
+class Panel {
+ public:
+  Panel(const Panel&) = delete;
+  Panel& operator=(const Panel&) = delete;
+
+  Panel(Panel&&) noexcept = default;
+  Panel& operator=(Panel&&) noexcept = default;
+
+  explicit Panel(std::string name = {}) : name{std::move(name)} {}
+  virtual ~Panel() = default;
+
+  virtual void onUpdate(const FrameInfo& frameInfo) = 0;
+
+  const std::string& getName() const { return name; }
+
+  bool isVisible() const { return this->visible; }
+  void setVisible(bool visible) { this->visible = visible; }
+  void toggleVisible() { this->visible = !this->visible; }
+
+ protected:
+  bool visible = true;
+
+ private:
+  std::string name;
+};
+
+}  // namespace sophia

engine/include/sophia/ui/panel_registry.hpp

@@ -0,0 +1,107 @@
+#pragma once
+
+#include <memory>
+#include <sophia/frame_info.hpp>
+#include <sophia/handles.hpp>
+#include <sophia/ui/panel.hpp>
+#include <sophia/util/assert.hpp>
+#include <string_view>
+#include <typeinfo>
+#include <utility>
+#include <vector>
+
+namespace sophia {
+
+class PanelRegistry {
+ public:
+  PanelRegistry(const PanelRegistry&) = delete;
+  PanelRegistry& operator=(const PanelRegistry&) = delete;
+
+  PanelRegistry() = default;
+  ~PanelRegistry() = default;
+
+  PanelHandle add(std::unique_ptr<Panel> 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));
+  }
+
+  template <typename T>
+  const T& get(PanelHandle handle) const {
+    const Panel& panel = get(handle);
+    SOPHIA_ASSERT(dynamic_cast<const T*>(&panel) != nullptr,
+                  "PanelHandle does not refer to a", typeid(T).name());
+    return static_cast<const T&>(panel);
+  }
+
+  template <typename T>
+  T& get(PanelHandle handle) {
+    return const_cast<T&>(std::as_const(*this).template get<T>(handle));
+  }
+
+  void remove(PanelHandle handle);
+  bool isValid(PanelHandle handle) const;
+
+  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;
+  }
+
+  template <typename T>
+  T* find() {
+    return const_cast<T*>(std::as_const(*this).template find<T>());
+  }
+
+  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;
+  }
+
+  Panel* find(std::string_view name) {
+    return const_cast<Panel*>(std::as_const(*this).find(name));
+  }
+
+  u32 size() const;
+  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());
+      }
+    }
+    return result;
+  }
+
+  void update(const FrameInfo& frameInfo);
+
+ private:
+  struct Slot {
+    std::unique_ptr<Panel> panel;
+    u32 generation = 0;
+  };
+
+  std::vector<Slot> slots;
+  std::vector<u32> freeList;
+};
+
+}  // namespace sophia

engine/src/application.cpp

@@ -10,10 +10,13 @@
 
 #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"
@@ -49,72 +52,10 @@ class Application::Impl {
         device{&window},
         renderContext{window, device} {}
 
-  /*void run(const std::string& vertShaderPath,
-             const std::string& fragShaderPath) {
-      log::info("Running Render Triangle Test...");
-
-      RenderContext renderContext{window, device};
-
-      auto vertexShader = Shader::Builder()
-                              .fromGLSL(vertShaderPath)
-                              .setStage(ShaderStage::VERTEX)
-                              .build();
-      auto fragmentShader = Shader::Builder()
-                                .fromGLSL(fragShaderPath)
-                                .setStage(ShaderStage::FRAGMENT)
-                                .build();
-
-      vk::PushConstantRange pushConstantRange{};
-      pushConstantRange.stageFlags =
-          vk::ShaderStageFlagBits::eVertex | vk::ShaderStageFlagBits::eFragment;
-      pushConstantRange.offset = 0;
-      pushConstantRange.size = sizeof(PushConstants);
-
-      vk::PipelineLayoutCreateInfo pipelineLayoutInfo{};
-      pipelineLayoutInfo.pushConstantRangeCount = 1;
-      pipelineLayoutInfo.pPushConstantRanges = &pushConstantRange;
-
-      vk::UniquePipelineLayout pipelineLayout =
-          device.get()->createPipelineLayoutUnique(pipelineLayoutInfo);
-
-      std::vector<vk::VertexInputBindingDescription> bindingDescriptions{
-          {0, sizeof(Vertex), vk::VertexInputRate::eVertex}};
-      std::vector<vk::VertexInputAttributeDescription> attributeDescriptions{
-          {0, 0, vk::Format::eR32G32Sfloat, offsetof(Vertex, position)},
-          {1, 0, vk::Format::eR32G32B32Sfloat, offsetof(Vertex, color)}};
-
-      std::unique_ptr<sophia::GraphicsPipeline> graphicsPipeline =
-          GraphicsPipeline::Builder(device)
-              .setVertexShader(*vertexShader)
-              .setFragmentShader(*fragmentShader)
-              .setPipelineLayout(pipelineLayout.get())
-              .setColorAttachmentFormats({renderContext.getImageFormat()})
-              .setVertexInput(bindingDescriptions, attributeDescriptions)
-              .build();
-
-      // Oversized triangle covering the full screen so the fragment shader runs
-      // for every pixel.
-      std::vector<Vertex> vertices{
-          {{-1.0f, -1.0f}, {1.0f, 0.0f, 0.0f}},
-          {{3.0f, -1.0f}, {0.0f, 1.0f, 0.0f}},
-          {{-1.0f, 3.0f}, {0.0f, 0.0f, 1.0f}},
-      };
-
-      Buffer vertexBuffer{device, sizeof(Vertex),
-                          static_cast<u32>(vertices.size()),
-                          vk::BufferUsageFlagBits::eVertexBuffer,
-                          vk::MemoryPropertyFlagBits::eHostVisible |
-                              vk::MemoryPropertyFlagBits::eHostCoherent};
-      vertexBuffer.map();
-      vertexBuffer.writeToBuffer(vertices.data(),
-                                 sizeof(Vertex) * vertices.size());
-      vertexBuffer.unmap();
-
-
-    }*/
-
   void run() {
     ModelRenderSystem modelRenderSystem{device, renderContext};
+    ImGuiRenderer imguiRenderer{window, device, renderContext.getImageFormat(),
+                                renderContext.getImageCount()};
 
     this->application.onCreate();
 
@@ -139,7 +80,6 @@ class Application::Impl {
                                     static_cast<float>(extent.height)),
                           this->application.camera};
       this->application.onUpdate(frameInfo);
-      this->application.onRender();
       this->application.camera.setProjection(
           -frameInfo.currentFramebufferExtent.x / 2.f,
           frameInfo.currentFramebufferExtent.x / 2.f,
@@ -151,6 +91,11 @@ class Application::Impl {
         continue;
       }
 
+      imguiRenderer.beginFrame();
+
+      this->application.panelRegistry.update(frameInfo);
+      this->application.onRender();
+
       renderContext.transitionCurrentImage(
           commandBuffer, vk::ImageLayout::eColorAttachmentOptimal);
 
@@ -183,7 +128,18 @@ class Application::Impl {
       commandBuffer.setViewport(0, viewport);
       commandBuffer.setScissor(0, scissor);
 
-      modelRenderSystem.render(commandBuffer, this->meshes, frameInfo);
+      std::vector<ModelRenderSystem::MeshInstance> instances;
+      instances.reserve(this->meshes.size() + this->drawCalls.size());
+      for (const std::unique_ptr<Mesh>& mesh : this->meshes) {
+        instances.push_back({mesh.get(), glm::mat4{1.f}});
+      }
+      instances.insert(instances.end(), this->drawCalls.begin(),
+                       this->drawCalls.end());
+
+      modelRenderSystem.render(commandBuffer, instances, frameInfo);
+      this->drawCalls.clear();
+
+      imguiRenderer.endFrame(commandBuffer);
 
       commandBuffer.endRendering();
 
@@ -224,6 +180,12 @@ class Application::Impl {
     this->meshes.clear();
   }
 
+  void drawMesh(const Mesh& mesh, const glm::mat4& transform) {
+    this->drawCalls.push_back({&mesh, transform});
+  }
+
+  Device& getDevice() { return device; }
+
  private:
   Application& application;
   const Application::Config config;
@@ -232,6 +194,7 @@ class Application::Impl {
   RenderContext renderContext;
 
   std::vector<std::unique_ptr<Mesh>> meshes;
+  std::vector<ModelRenderSystem::MeshInstance> drawCalls;
 };
 
 void Application::setCommandLineArgs(int argc, const char* const* argv) {
@@ -241,7 +204,9 @@ void Application::setCommandLineArgs(int argc, const char* const* argv) {
 Application::Application(const Config& config)
     : impl{std::make_unique<Impl>(*this, config)},
       canvas{this},
-      args{std::move(commandLineArgs)} {}
+      args{std::move(commandLineArgs)},
+      assetRegistry{impl->getDevice()},
+      _debugUI{this->panelRegistry} {}
 
 Application::~Application() = default;
 
@@ -254,4 +219,8 @@ 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);
+}
+
 }  // namespace sophia

engine/src/assets/asset_registry.cpp

@@ -0,0 +1,60 @@
+#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

@@ -0,0 +1,58 @@
+#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

@@ -0,0 +1,35 @@
+#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/imgui_renderer.cpp

@@ -0,0 +1,85 @@
+#include "imgui_renderer.hpp"
+
+#include <imgui.h>
+#include <imgui_impl_glfw.h>
+#include <imgui_impl_vulkan.h>
+
+namespace sophia {
+
+ImGuiRenderer::ImGuiRenderer(Window& window, Device& device,
+                             vk::Format colorAttachmentFormat,
+                             u32 minImageCount) {
+  // 1. Construct ImGui context
+  IMGUI_CHECKVERSION();
+  ImGui::CreateContext();
+
+  ImGui_ImplGlfw_InitForVulkan(window.getGLFWwindow(), true);
+
+  ImGui_ImplVulkan_InitInfo initInfo = {};
+  device.populateImGuiInitInfo(initInfo);
+  initInfo.DescriptorPoolSize =
+      IMGUI_IMPL_VULKAN_MINIMUM_SAMPLED_IMAGE_POOL_SIZE + 5;
+  initInfo.MinImageCount = minImageCount;
+  initInfo.ImageCount = minImageCount;
+
+  VkFormat rawColorAttachmentFormat =
+      static_cast<VkFormat>(colorAttachmentFormat);
+  initInfo.UseDynamicRendering = true;
+  initInfo.PipelineInfoMain.PipelineRenderingCreateInfo.sType =
+      VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR;
+  initInfo.PipelineInfoMain.PipelineRenderingCreateInfo.colorAttachmentCount =
+      1;
+  initInfo.PipelineInfoMain.PipelineRenderingCreateInfo
+      .pColorAttachmentFormats = &rawColorAttachmentFormat;
+
+  ImGui_ImplVulkan_Init(&initInfo);
+
+  // 2. Enable dark theme
+  ImGui::StyleColorsDark();
+
+  // 3. Enable docking / keyboard
+  ImGuiIO& io = ImGui::GetIO();
+  io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
+  io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
+  io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
+
+  /**
+   * When viewports are enabled we tweak WindowRounding/WindowBg so
+   * platform windows can look identical to regular ones.
+   */
+  ImGuiStyle& style = ImGui::GetStyle();
+  if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
+    style.WindowRounding = 0.0f;
+    style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+  }
+}
+
+ImGuiRenderer::~ImGuiRenderer() {
+  ImGui_ImplVulkan_Shutdown();
+  ImGui_ImplGlfw_Shutdown();
+  ImGui::DestroyContext();
+}
+
+void ImGuiRenderer::beginFrame() {
+  ImGui_ImplVulkan_NewFrame();
+  ImGui_ImplGlfw_NewFrame();
+  ImGui::NewFrame();
+
+  ImGui::DockSpaceOverViewport(0, ImGui::GetMainViewport(),
+                               ImGuiDockNodeFlags_PassthruCentralNode);
+}
+
+void ImGuiRenderer::endFrame(vk::CommandBuffer commandBuffer) {
+  ImGui::Render();
+  ImDrawData* mainDrawData = ImGui::GetDrawData();
+
+  ImGuiIO& io = ImGui::GetIO();
+  if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
+    ImGui::UpdatePlatformWindows();
+    ImGui::RenderPlatformWindowsDefault();
+  }
+
+  ImGui_ImplVulkan_RenderDrawData(mainDrawData, commandBuffer);
+}
+
+}  // namespace sophia

engine/src/imgui_renderer.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <sophia/types.hpp>
+
+#include "device.hpp"
+#include "window.hpp"
+
+namespace sophia {
+
+class ImGuiRenderer {
+ public:
+  ImGuiRenderer(const ImGuiRenderer&) = delete;
+  ImGuiRenderer& operator=(const ImGuiRenderer&) = delete;
+
+  ImGuiRenderer(Window& window, Device& device,
+                vk::Format colorAttachmentFormat, u32 minImageCount);
+  ~ImGuiRenderer();
+
+  void beginFrame();
+  void endFrame(vk::CommandBuffer commandBuffer);
+};
+
+}  // namespace sophia

engine/src/mesh.cpp

@@ -36,7 +36,7 @@ Mesh::Mesh(Device& device, const Builder& builder) : device{device} {
   createIndexBuffers(builder.indices);
 }
 
-Mesh::~Mesh() {}
+Mesh::~Mesh() = default;
 
 void Mesh::bind(vk::CommandBuffer commandBuffer) const {
   vk::Buffer buffers[] = {this->vertexBuffer->getBuffer()};

engine/src/mesh.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <memory>
+#include <sophia/asset_registry.hpp>
 #include <sophia/types.hpp>
 #include <vector>
 

engine/src/render_context.cpp

@@ -142,8 +142,6 @@ void RenderContext::recreateSwapchain() {
   // Old fences referred to images owned by the now-replaced swapchain;
   // there's nothing valid left to wait on.
   this->imagesInFlight.assign(this->swapchain->imageCount(), vk::Fence{});
-
-  log::trace("recreated swapchain");
 }
 
 void RenderContext::createFrames() {

engine/src/render_context.hpp

@@ -45,6 +45,9 @@ class RenderContext {
   vk::Format getImageFormat() const {
     return this->swapchain->getImageFormat();
   }
+  u32 getImageCount() const {
+    return static_cast<u32>(this->swapchain->imageCount());
+  }
 
  private:
   void recreateSwapchain();

engine/src/scene.cpp

@@ -0,0 +1,17 @@
+#include "scene.hpp"
+
+#include <sophia/components.hpp>
+#include <sophia/util/logger.hpp>
+
+namespace sophia {
+
+Scene::Scene() {
+  entt::entity entity = this->registry.create();
+
+  auto& a = this->registry.emplace<TransformComponent>(entity);
+  auto& b = this->registry.get<TransformComponent>(entity);
+}
+
+Scene::~Scene() { log::trace("destroying sophia::Scene"); }
+
+}  // namespace sophia

engine/src/scene.hpp

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

engine/src/swapchain.cpp

@@ -186,7 +186,7 @@ vk::PresentModeKHR Swapchain::choosePresentMode(
       bestMode = availablePresentMode;
     }
   }
-  log::warning("Present mode MAILBOX not available.");
+  log::trace("Present mode MAILBOX not available.");
 
   if (bestMode == vk::PresentModeKHR::eImmediate) {
     log::info("Selected present mode: IMMEDIATE (no vsync)");

engine/src/systems/model_render_system.cpp

@@ -1,6 +1,6 @@
 #include "model_render_system.hpp"
 
-#include <cassert>
+#include <sophia/util/assert.hpp>
 
 #include "shaders/model_render_system.frag.spv.h"
 #include "shaders/model_render_system.vert.spv.h"
@@ -12,7 +12,7 @@ ModelRenderSystem::ModelRenderSystem(Device& device,
     : device{device}, renderContext{renderContext} {
   createPipelineLayout();
 
-  assert(this->pipelineLayout.get() != nullptr &&
+  SOPHIA_ASSERT(this->pipelineLayout.get() != nullptr,
                 "Cannot create pipeline before pipeline layout");
 
   auto vertexShader = Shader::Builder()
@@ -42,23 +42,23 @@ ModelRenderSystem::~ModelRenderSystem() {
 }
 
 void ModelRenderSystem::render(vk::CommandBuffer commandBuffer,
-                               std::span<const std::unique_ptr<Mesh>> meshes,
+                               std::span<const MeshInstance> instances,
                                const FrameInfo& frameInfo) {
   glm::mat4 viewProjection = frameInfo.camera.getViewProjection();
 
   this->graphicsPipeline->bind(commandBuffer);
 
-  for (const std::unique_ptr<Mesh>& mesh : meshes) {
+  for (const MeshInstance& instance : instances) {
     PushConstantData push{};
-    push.modelMatrix = viewProjection;
+    push.transform = viewProjection * instance.transform;
 
     commandBuffer.pushConstants(
         this->pipelineLayout.get(),
         vk::ShaderStageFlagBits::eVertex | vk::ShaderStageFlagBits::eFragment,
         0, sizeof(PushConstantData), &push);
 
-    mesh->bind(commandBuffer);
+    instance.mesh->bind(commandBuffer);
-    mesh->draw(commandBuffer);
+    instance.mesh->draw(commandBuffer);
   }
 }
 

engine/src/systems/model_render_system.hpp

@@ -13,9 +13,15 @@ namespace sophia {
 
 class ModelRenderSystem {
  public:
+  // Layout must match the shader's `Push` block in model_render_system.vert.
   struct PushConstantData {
-    glm::mat4 modelMatrix{1.f};
+    glm::mat4 transform{1.f};
-    glm::mat4 normalMatrix{1.f};
+    glm::vec4 color{1.f};
+  };
+
+  struct MeshInstance {
+    const Mesh* mesh;
+    glm::mat4 transform{1.f};
   };
 
   ModelRenderSystem(const ModelRenderSystem&) = delete;
@@ -25,7 +31,7 @@ class ModelRenderSystem {
   ~ModelRenderSystem();
 
   void render(vk::CommandBuffer commandBuffer,
-              std::span<const std::unique_ptr<Mesh>> meshes,
+              std::span<const MeshInstance> instances,
               const FrameInfo& frameInfo);
 
  private:

engine/src/ui/debug_ui.cpp

@@ -0,0 +1,47 @@
+#include <sophia/ui/debug_ui.hpp>
+
+#include "panels/console_panel.hpp"
+#include "panels/frame_stats_panel.hpp"
+#include "panels/panel_registry_panel.hpp"
+
+namespace sophia {
+
+DebugUI::DebugUI(PanelRegistry& registry) : registry{registry} {
+  // #ifndef NDEBUG
+  this->panelRegistryHandle = registry.emplace<PanelRegistryPanel>(registry);
+  this->frameStatsHandle = registry.emplace<FrameStatsPanel>();
+  this->consoleHandle = registry.emplace<ConsolePanel>();
+  // #endif  // !NDEBUG
+}
+
+void DebugUI::show() {
+  showPanelRegistry(true);
+  showFrameStats(true);
+  showConsole(true);
+}
+
+void DebugUI::hide() {
+  showPanelRegistry(false);
+  showFrameStats(false);
+  showConsole(false);
+}
+
+void DebugUI::showPanelRegistry(bool show) {
+  if (registry.isValid(panelRegistryHandle)) {
+    registry.get(panelRegistryHandle).setVisible(show);
+  }
+}
+
+void DebugUI::showFrameStats(bool show) {
+  if (registry.isValid(frameStatsHandle)) {
+    registry.get(frameStatsHandle).setVisible(show);
+  }
+}
+
+void DebugUI::showConsole(bool show) {
+  if (registry.isValid(consoleHandle)) {
+    registry.get(consoleHandle).setVisible(show);
+  }
+}
+
+}  // namespace sophia

engine/src/ui/panel_registry.cpp

@@ -0,0 +1,88 @@
+#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()) {
+      count++;
+    }
+  }
+  return count;
+}
+
+void PanelRegistry::update(const FrameInfo& frameInfo) {
+  for (auto& slot : slots) {
+    if (slot.panel && slot.panel->isVisible()) {
+      slot.panel->onUpdate(frameInfo);
+    }
+  }
+}
+
+}  // namespace sophia

engine/src/ui/panels/console_panel.cpp

@@ -0,0 +1,136 @@
+#include "console_panel.hpp"
+
+#include <algorithm>
+
+namespace sophia {
+
+namespace {
+constexpr ImVec4 COLOR_DEFAULT = ImVec4(0.85f, 0.85f, 0.85f, 1.0f);
+constexpr ImVec4 COLOR_COMMAND = ImVec4(1.0f, 0.78f, 0.37f, 1.0f);
+constexpr ImVec4 COLOR_ERROR = ImVec4(1.0f, 0.4f, 0.4f, 1.0f);
+constexpr ImVec4 COLOR_INFO = ImVec4(0.4f, 0.7f, 1.0f, 1.0f);
+}  // namespace
+
+void ConsolePanel::registerDefaultCommands() {
+  log("Console ready. Type 'help' for a list of commands.");
+}
+
+void ConsolePanel::log(const std::string& message) {
+  entries.push_back(Entry{message, COLOR_DEFAULT});
+  scrollToBottom = true;
+}
+
+void ConsolePanel::clear() { entries.clear(); }
+
+void ConsolePanel::execute(const std::string& command) {
+  entries.push_back(Entry{"> " + command, COLOR_COMMAND});
+  scrollToBottom = true;
+
+  historyPos = -1;
+  history.erase(std::remove(history.begin(), history.end(), command),
+                history.end());
+  history.push_back(command);
+
+  if (command == "help") {
+    entries.push_back(
+        Entry{"Available commands: help, clear, history", COLOR_INFO});
+  } else if (command == "clear") {
+    clear();
+  } else if (command == "history") {
+    for (const std::string& past : history) {
+      entries.push_back(Entry{past, COLOR_DEFAULT});
+    }
+  } else if (commandCallback) {
+    commandCallback(*this, command);
+  } else {
+    entries.push_back(Entry{"Unknown command: '" + command + "'", COLOR_ERROR});
+  }
+}
+
+int ConsolePanel::textEditCallback(ImGuiInputTextCallbackData* data) {
+  if (data->EventFlag != ImGuiInputTextFlags_CallbackHistory) {
+    return 0;
+  }
+
+  const int previousPos = historyPos;
+  if (data->EventKey == ImGuiKey_UpArrow) {
+    if (historyPos == -1) {
+      historyPos = static_cast<int>(history.size()) - 1;
+    } else if (historyPos > 0) {
+      historyPos--;
+    }
+  } else if (data->EventKey == ImGuiKey_DownArrow) {
+    if (historyPos != -1 && ++historyPos >= static_cast<int>(history.size())) {
+      historyPos = -1;
+    }
+  }
+
+  if (previousPos != historyPos) {
+    const std::string& historyStr =
+        historyPos >= 0 ? history[static_cast<size_t>(historyPos)] : "";
+    data->DeleteChars(0, data->BufTextLen);
+    data->InsertChars(0, historyStr.c_str());
+  }
+
+  return 0;
+}
+
+void ConsolePanel::onUpdate(const FrameInfo&) {
+  ImGui::Begin("Console");
+
+  if (ImGui::SmallButton("Clear")) {
+    clear();
+  }
+  ImGui::SameLine();
+  ImGui::Checkbox("Auto-scroll", &autoScroll);
+
+  ImGui::Separator();
+
+  const float footerHeight =
+      ImGui::GetStyle().ItemSpacing.y + ImGui::GetFrameHeightWithSpacing();
+  ImGui::BeginChild("ScrollRegion", ImVec2(0, -footerHeight), false,
+                    ImGuiWindowFlags_HorizontalScrollbar);
+
+  for (const Entry& entry : entries) {
+    ImGui::PushStyleColor(ImGuiCol_Text, entry.color);
+    ImGui::TextUnformatted(entry.text.c_str());
+    ImGui::PopStyleColor();
+  }
+
+  if (scrollToBottom ||
+      (autoScroll && ImGui::GetScrollY() >= ImGui::GetScrollMaxY())) {
+    ImGui::SetScrollHereY(1.0f);
+  }
+  scrollToBottom = false;
+
+  ImGui::EndChild();
+  ImGui::Separator();
+
+  ImGuiInputTextFlags inputFlags = ImGuiInputTextFlags_EnterReturnsTrue |
+                                   ImGuiInputTextFlags_CallbackHistory;
+
+  bool reclaimFocus = false;
+  if (ImGui::InputText(
+          "Input", inputBuffer, sizeof(inputBuffer), inputFlags,
+          [](ImGuiInputTextCallbackData* data) -> int {
+            auto* console = static_cast<ConsolePanel*>(data->UserData);
+            return console->textEditCallback(data);
+          },
+          this)) {
+    std::string command{inputBuffer};
+    if (!command.empty()) {
+      execute(command);
+    }
+    inputBuffer[0] = '\0';
+    reclaimFocus = true;
+  }
+
+  ImGui::SetItemDefaultFocus();
+  if (reclaimFocus) {
+    ImGui::SetKeyboardFocusHere(-1);
+  }
+
+  ImGui::End();
+}
+
+}  // namespace sophia

engine/src/ui/panels/console_panel.hpp

@@ -0,0 +1,50 @@
+#pragma once
+
+#include <imgui.h>
+
+#include <functional>
+#include <sophia/frame_info.hpp>
+#include <sophia/ui/panel.hpp>
+#include <string>
+#include <vector>
+
+namespace sophia {
+
+class ConsolePanel : public Panel {
+ public:
+  using CommandCallback =
+      std::function<void(ConsolePanel&, const std::string&)>;
+
+  ConsolePanel() : Panel{"Console"} { registerDefaultCommands(); }
+
+  void onUpdate(const FrameInfo& frameInfo) override;
+
+  void log(const std::string& message);
+  void clear();
+
+  void setCommandCallback(CommandCallback callback) {
+    this->commandCallback = std::move(callback);
+  }
+
+ private:
+  struct Entry {
+    std::string text;
+    ImVec4 color;
+  };
+
+  void registerDefaultCommands();
+  void execute(const std::string& command);
+  int textEditCallback(struct ImGuiInputTextCallbackData* data);
+
+  std::vector<Entry> entries;
+  std::vector<std::string> history;
+  int historyPos = -1;
+
+  char inputBuffer[256] = {};
+  bool autoScroll = true;
+  bool scrollToBottom = false;
+
+  CommandCallback commandCallback;
+};
+
+}  // namespace sophia

engine/src/ui/panels/ecs_inspector_panel.cpp

@@ -0,0 +1,57 @@
+#include "ecs_inspector_panel.hpp"
+
+#include <imgui.h>
+
+#include <sophia/components.hpp>
+
+namespace sophia {
+
+void EcsInspectorPanel::onUpdate(const FrameInfo&) {
+  ImGui::Begin("ECS Inspector");
+
+  entityScratch.clear();
+  for (entt::entity entity : registry.storage<entt::entity>()) {
+    entityScratch.push_back(entity);
+  }
+
+  ImGui::BeginChild("EntityList", ImVec2(0, 200), true);
+  ImGuiListClipper clipper;
+  clipper.Begin(static_cast<int>(entityScratch.size()));
+  while (clipper.Step()) {
+    for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++) {
+      entt::entity entity = entityScratch[static_cast<size_t>(i)];
+      const TagComponent* tag = registry.try_get<TagComponent>(entity);
+      std::string label = tag ? tag->tag : "Entity";
+
+      ImGui::PushID(static_cast<int>(entt::to_integral(entity)));
+      if (ImGui::Selectable(label.c_str(), selected == entity)) {
+        selected = entity;
+      }
+      ImGui::PopID();
+    }
+  }
+  ImGui::EndChild();
+
+  ImGui::Separator();
+
+  if (registry.valid(selected)) {
+    if (auto* transform = registry.try_get<TransformComponent>(selected)) {
+      ImGui::DragFloat3("Position", &transform->position.x, 0.1f);
+      ImGui::DragFloat3("Scale", &transform->scale.x, 0.1f);
+      ImGui::Text("Rotation: %.2f, %.2f, %.2f, %.2f", transform->rotation.w,
+                  transform->rotation.x, transform->rotation.y,
+                  transform->rotation.z);
+    }
+
+    if (auto* mesh = registry.try_get<MeshComponent>(selected)) {
+      ImGui::Text("Mesh: index=%u generation=%u", mesh->handle.index,
+                  mesh->handle.generation);
+    }
+  } else {
+    ImGui::TextDisabled("No entity selected");
+  }
+
+  ImGui::End();
+}
+
+}  // namespace sophia

engine/src/ui/panels/ecs_inspector_panel.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <entt/entt.hpp>
+#include <sophia/frame_info.hpp>
+#include <sophia/ui/panel.hpp>
+#include <vector>
+
+namespace sophia {
+
+class EcsInspectorPanel : public Panel {
+ public:
+  explicit EcsInspectorPanel(entt::registry& registry)
+      : Panel{"ECS Inspector"}, registry{registry} {}
+
+  void onUpdate(const FrameInfo& frameInfo) override;
+
+ private:
+  entt::registry& registry;
+  entt::entity selected = entt::null;
+  std::vector<entt::entity> entityScratch;
+};
+
+}  // namespace sophia

engine/src/ui/panels/frame_stats_panel.hpp

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <imgui.h>
+
+#include <sophia/frame_info.hpp>
+#include <sophia/ui/panel.hpp>
+
+namespace sophia {
+
+class FrameStatsPanel : public Panel {
+ public:
+  FrameStatsPanel() : Panel{"Frame Stats"} {}
+
+  void onUpdate(const FrameInfo& frameInfo) override {
+    frameCount++;
+    accumulatedTime += frameInfo.deltaTime;
+
+    if (frameInfo.elapsedTime >= nextRefreshTime) {
+      displayedFps = static_cast<double>(frameCount) / accumulatedTime;
+      displayedFrameTimeMs =
+          (accumulatedTime / static_cast<double>(frameCount)) * 1000.0;
+
+      frameCount = 0;
+      accumulatedTime = 0.0;
+      nextRefreshTime = frameInfo.elapsedTime + REFRESH_INTERVAL;
+    }
+
+    ImGui::Begin("Frame Stats");
+    ImGui::Text("FPS: %.1f", displayedFps);
+    ImGui::Text("Frame time: %.3f ms", displayedFrameTimeMs);
+    ImGui::End();
+  }
+
+ private:
+  static constexpr double REFRESH_INTERVAL = 1.0;
+
+  double accumulatedTime = 0.0;
+  u32 frameCount = 0;
+  double nextRefreshTime = 0.0;
+  double displayedFps = 0.0;
+  double displayedFrameTimeMs = 0.0;
+};
+
+}  // namespace sophia

engine/src/ui/panels/panel_registry_panel.cpp

@@ -0,0 +1,28 @@
+#include "panel_registry_panel.hpp"
+
+#include <imgui.h>
+
+namespace sophia {
+
+void PanelRegistryPanel::onUpdate(const FrameInfo&) {
+  ImGui::Begin("PanelRegistry");
+  ImGui::Text("%u panels (%u visible)", registry.size(),
+              registry.visibleCount());
+  ImGui::Separator();
+
+  for (std::string_view name : registry.names()) {
+    Panel* panel = registry.find(name);
+    if (!panel || panel == this) {
+      continue;
+    }
+
+    bool visible = panel->isVisible();
+    if (ImGui::Checkbox(name.data(), &visible)) {
+      panel->setVisible(visible);
+    }
+  }
+
+  ImGui::End();
+}
+
+}  // namespace sophia

engine/src/ui/panels/panel_registry_panel.hpp

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <sophia/frame_info.hpp>
+#include <sophia/ui/panel.hpp>
+#include <sophia/ui/panel_registry.hpp>
+
+namespace sophia {
+
+class PanelRegistryPanel : public Panel {
+ public:
+  explicit PanelRegistryPanel(PanelRegistry& registry)
+      : Panel{"PanelRegistry"}, registry{registry} {}
+
+  void onUpdate(const FrameInfo& frameInfo) override;
+
+ private:
+  PanelRegistry& registry;
+};
+
+}  // namespace sophia

examples/boids_2d/CMakeLists.txt

@@ -0,0 +1,3 @@
+add_executable(boids_2d main.cpp)
+
+target_link_libraries(boids_2d PRIVATE ${PROJECT_NAME})

examples/boids_2d/main.cpp

@@ -0,0 +1,248 @@
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
+#include <iostream>
+#include <random>
+#include <sophia/application.hpp>
+#include <sophia/event.hpp>
+#include <sophia/key_event.hpp>
+#include <stdexcept>
+#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;
+};
+
+constexpr uint32_t DEFAULT_NUMBER_OF_BOIDS = 25;
+
+class Boids2D : public sophia::Application {
+ public:
+  static constexpr float SCROLL_SPEED = 200.0f;
+
+  // World is a fixed box independent of the camera; boids wrap at its edges.
+  static constexpr float WORLD_HALF_WIDTH = 1000.0f;
+  static constexpr float WORLD_HALF_HEIGHT = 1000.0f;
+
+  static constexpr float MAX_SPEED = 120.0f;
+  static constexpr float MAX_FORCE = 200.0f;
+  static constexpr float PERCEPTION_RADIUS = 150.0f;
+  static constexpr float SEPARATION_RADIUS = 40.0f;
+  static constexpr float ALIGNMENT_WEIGHT = 1.0f;
+  static constexpr float COHESION_WEIGHT = 1.0f;
+  static constexpr float SEPARATION_WEIGHT = 1.5f;
+
+  static constexpr float BOID_LENGTH = 20.0f;
+  static constexpr float BOID_WIDTH = 12.0f;
+
+  // Neighbor lookups use a uniform grid instead of an O(n^2) scan. Cell size
+  // equals PERCEPTION_RADIUS so that a boid's neighbors can only ever fall in
+  // its own cell or the 8 cells surrounding it.
+  static constexpr float CELL_SIZE = PERCEPTION_RADIUS;
+  static constexpr int GRID_WIDTH =
+      static_cast<int>(2.0f * WORLD_HALF_WIDTH / CELL_SIZE) + 1;
+  static constexpr int GRID_HEIGHT =
+      static_cast<int>(2.0f * WORLD_HALF_HEIGHT / CELL_SIZE) + 1;
+
+  Boids2D() : Application{{.width = 750, .height = 1000, .name = "Boids2D"}} {
+    uint32_t numberOfBoids = DEFAULT_NUMBER_OF_BOIDS;
+    if (args.size() > 1) {
+      numberOfBoids = static_cast<uint32_t>(std::stoul(args[1]));
+    }
+    boids.resize(numberOfBoids);
+
+    sophia::EventSystem::get().addListener<sophia::KeyPressedEvent>(
+        [this](sophia::KeyPressedEvent& e) {
+          setScrollKeyHeld(e.getKeyCode(), true);
+        });
+    sophia::EventSystem::get().addListener<sophia::KeyReleasedEvent>(
+        [this](sophia::KeyReleasedEvent& e) {
+          setScrollKeyHeld(e.getKeyCode(), false);
+        });
+  }
+
+  void onCreate() override {
+    std::cout << "Boids2D created" << std::endl;
+
+    std::mt19937 rng{std::random_device{}()};
+    std::uniform_real_distribution<float> posX{-WORLD_HALF_WIDTH,
+                                               WORLD_HALF_WIDTH};
+    std::uniform_real_distribution<float> posY{-WORLD_HALF_HEIGHT,
+                                               WORLD_HALF_HEIGHT};
+    std::uniform_real_distribution<float> angle{0.0f, glm::two_pi<float>()};
+
+    for (Boid& boid : boids) {
+      boid.position = {posX(rng), posY(rng)};
+      float theta = angle(rng);
+      boid.velocity = glm::vec2{std::cos(theta), std::sin(theta)} * MAX_SPEED;
+    }
+
+    // Boid shape in local space, nose pointing along +x; each boid is drawn
+    // as an instance of this one mesh with a per-boid transform.
+    std::vector<sophia::CanvasVertex> vertices{
+        {{BOID_LENGTH * 0.5f, 0.0f}, {1.0f, 1.0f, 1.0f}},
+        {{-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), {});
+  }
+
+  void onUpdate(const sophia::FrameInfo& frameInfo) override {
+    float scrollDistance =
+        SCROLL_SPEED * static_cast<float>(frameInfo.deltaTime);
+    if (scrollLeft) camera.position.x -= scrollDistance;
+    if (scrollRight) camera.position.x += scrollDistance;
+    if (scrollUp) camera.position.y -= scrollDistance;
+    if (scrollDown) camera.position.y += scrollDistance;
+
+    updateBoids(static_cast<float>(frameInfo.deltaTime));
+
+    for (const Boid& boid : boids) {
+      drawBoid(boid);
+    }
+  }
+
+ private:
+  // Maps a world position to its grid cell, clamped to the grid bounds.
+  glm::ivec2 cellOf(glm::vec2 position) const {
+    int cx = static_cast<int>((position.x + WORLD_HALF_WIDTH) / CELL_SIZE);
+    int cy = static_cast<int>((position.y + WORLD_HALF_HEIGHT) / CELL_SIZE);
+    return {std::clamp(cx, 0, GRID_WIDTH - 1),
+            std::clamp(cy, 0, GRID_HEIGHT - 1)};
+  }
+
+  void rebuildGrid() {
+    for (std::vector<uint32_t>& cell : grid) cell.clear();
+
+    for (uint32_t i = 0; i < boids.size(); ++i) {
+      glm::ivec2 cell = cellOf(boids[i].position);
+      grid[cell.y * GRID_WIDTH + cell.x].push_back(i);
+    }
+  }
+
+  void updateBoids(float deltaTime) {
+    rebuildGrid();
+
+    std::vector<glm::vec2> accelerations(boids.size());
+
+    for (size_t i = 0; i < boids.size(); ++i) {
+      glm::vec2 separation{0.0f};
+      glm::vec2 averageVelocity{0.0f};
+      glm::vec2 averagePosition{0.0f};
+      int neighborCount = 0;
+
+      glm::ivec2 cell = cellOf(boids[i].position);
+
+      for (int cy = std::max(cell.y - 1, 0);
+           cy <= std::min(cell.y + 1, GRID_HEIGHT - 1); ++cy) {
+        for (int cx = std::max(cell.x - 1, 0);
+             cx <= std::min(cell.x + 1, GRID_WIDTH - 1); ++cx) {
+          for (uint32_t j : grid[cy * GRID_WIDTH + cx]) {
+            if (j == i) continue;
+
+            glm::vec2 offset = boids[i].position - boids[j].position;
+            float dist = glm::length(offset);
+            if (dist >= PERCEPTION_RADIUS) continue;
+
+            averageVelocity += boids[j].velocity;
+            averagePosition += boids[j].position;
+            ++neighborCount;
+
+            if (dist > 0.0f && dist < SEPARATION_RADIUS) {
+              separation += offset / (dist * dist);
+            }
+          }
+        }
+      }
+
+      glm::vec2 acceleration =
+          steerTowards(boids[i], separation) * SEPARATION_WEIGHT;
+
+      if (neighborCount > 0) {
+        averageVelocity /= static_cast<float>(neighborCount);
+        acceleration +=
+            steerTowards(boids[i], averageVelocity) * ALIGNMENT_WEIGHT;
+
+        averagePosition /= static_cast<float>(neighborCount);
+        glm::vec2 towardsGroup = averagePosition - boids[i].position;
+        acceleration += steerTowards(boids[i], towardsGroup) * COHESION_WEIGHT;
+      }
+
+      accelerations[i] = acceleration;
+    }
+
+    for (size_t i = 0; i < boids.size(); ++i) {
+      Boid& boid = boids[i];
+      boid.velocity += accelerations[i] * deltaTime;
+
+      float speed = glm::length(boid.velocity);
+      if (speed > MAX_SPEED) {
+        boid.velocity = boid.velocity / speed * MAX_SPEED;
+      }
+
+      boid.position += boid.velocity * deltaTime;
+      wrapPosition(boid.position);
+    }
+  }
+
+  // Steers boid towards desiredDirection at up to MAX_SPEED, clamped to
+  // MAX_FORCE.
+  glm::vec2 steerTowards(const Boid& boid, glm::vec2 desiredDirection) {
+    float directionLength = glm::length(desiredDirection);
+    if (directionLength < 1e-5f) return glm::vec2{0.0f};
+
+    glm::vec2 desired = desiredDirection / directionLength * MAX_SPEED;
+    glm::vec2 steer = desired - boid.velocity;
+
+    float steerLength = glm::length(steer);
+    if (steerLength > MAX_FORCE) {
+      steer = steer / steerLength * MAX_FORCE;
+    }
+    return steer;
+  }
+
+  void wrapPosition(glm::vec2& position) {
+    if (position.x > WORLD_HALF_WIDTH) position.x = -WORLD_HALF_WIDTH;
+    if (position.x < -WORLD_HALF_WIDTH) position.x = WORLD_HALF_WIDTH;
+    if (position.y > WORLD_HALF_HEIGHT) position.y = -WORLD_HALF_HEIGHT;
+    if (position.y < -WORLD_HALF_HEIGHT) position.y = WORLD_HALF_HEIGHT;
+  }
+
+  void drawBoid(const Boid& boid) {
+    glm::vec2 direction = boid.velocity;
+    float speed = glm::length(direction);
+    direction = speed > 1e-5f ? direction / speed : glm::vec2{0.0f, -1.0f};
+    float angle = std::atan2(direction.y, direction.x);
+
+    glm::mat4 transform =
+        glm::translate(glm::mat4{1.f}, glm::vec3(boid.position, 0.0f)) *
+        glm::rotate(glm::mat4{1.f}, angle, glm::vec3(0.0f, 0.0f, 1.0f));
+
+    drawMesh(boidMesh, transform);
+  }
+
+  void setScrollKeyHeld(sophia::KeyCode keycode, bool held) {
+    if (keycode == sophia::Key::Left) scrollLeft = held;
+    if (keycode == sophia::Key::Right) scrollRight = held;
+    if (keycode == sophia::Key::Up) scrollUp = held;
+    if (keycode == sophia::Key::Down) scrollDown = held;
+  }
+
+  std::vector<Boid> boids;
+  std::vector<std::vector<uint32_t>> grid{
+      static_cast<size_t>(GRID_WIDTH * GRID_HEIGHT)};
+  sophia::MeshHandle boidMesh{};
+  bool scrollLeft = false;
+  bool scrollRight = false;
+  bool scrollUp = false;
+  bool scrollDown = false;
+};
+
+SOPHIA_MAIN(Boids2D)

testbed/main.cpp

@@ -1,200 +1,17 @@
-#include <cmath>
 #include <iostream>
-#include <random>
 #include <sophia/application.hpp>
-#include <sophia/event.hpp>
-#include <sophia/key_event.hpp>
-#include <stdexcept>
-#include <string>
-#include <vector>
-
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-#include <glm/gtc/constants.hpp>
-
-struct Boid {
-  glm::vec2 position;
-  glm::vec2 velocity;
-};
-
-constexpr uint32_t DEFAULT_NUMBER_OF_BOIDS = 25;
 
 class Testbed : public sophia::Application {
  public:
-  static constexpr float SCROLL_SPEED = 200.0f;
+  Testbed() : Application{{.width = 750, .height = 1000, .name = "Testbed"}} {}
-
-  // World is a fixed box independent of the camera; boids wrap at its edges.
-  static constexpr float WORLD_HALF_WIDTH = 375.0f;
-  static constexpr float WORLD_HALF_HEIGHT = 500.0f;
-
-  static constexpr float MAX_SPEED = 120.0f;
-  static constexpr float MAX_FORCE = 200.0f;
-  static constexpr float PERCEPTION_RADIUS = 150.0f;
-  static constexpr float SEPARATION_RADIUS = 40.0f;
-  static constexpr float ALIGNMENT_WEIGHT = 1.0f;
-  static constexpr float COHESION_WEIGHT = 1.0f;
-  static constexpr float SEPARATION_WEIGHT = 1.5f;
-
-  Testbed() : Application{{.width = 750, .height = 1000, .name = "Testbed"}} {
-    uint32_t numberOfBoids = DEFAULT_NUMBER_OF_BOIDS;
-    if (args.size() > 1) {
-      numberOfBoids = static_cast<uint32_t>(std::stoul(args[1]));
-    }
-    boids.resize(numberOfBoids);
-
-    sophia::EventSystem::get().addListener<sophia::KeyPressedEvent>(
-        [this](sophia::KeyPressedEvent& e) {
-          setScrollKeyHeld(e.getKeyCode(), true);
-        });
-    sophia::EventSystem::get().addListener<sophia::KeyReleasedEvent>(
-        [this](sophia::KeyReleasedEvent& e) {
-          setScrollKeyHeld(e.getKeyCode(), false);
-        });
-  }
 
   void onCreate() override {
     std::cout << "Testbed created" << std::endl;
 
-    std::mt19937 rng{std::random_device{}()};
+    debugUI().show();
-    std::uniform_real_distribution<float> posX{-WORLD_HALF_WIDTH,
-                                               WORLD_HALF_WIDTH};
-    std::uniform_real_distribution<float> posY{-WORLD_HALF_HEIGHT,
-                                               WORLD_HALF_HEIGHT};
-    std::uniform_real_distribution<float> angle{0.0f, glm::two_pi<float>()};
-
-    for (Boid& boid : boids) {
-      boid.position = {posX(rng), posY(rng)};
-      float theta = angle(rng);
-      boid.velocity = glm::vec2{std::cos(theta), std::sin(theta)} * MAX_SPEED;
-    }
   }
 
-  void onUpdate(const sophia::FrameInfo& frameInfo) override {
+  void onUpdate(const sophia::FrameInfo& frameInfo) override {}
-    float scrollDistance =
-        SCROLL_SPEED * static_cast<float>(frameInfo.deltaTime);
-    if (scrollLeft) camera.position.x -= scrollDistance;
-    if (scrollRight) camera.position.x += scrollDistance;
-    if (scrollUp) camera.position.y -= scrollDistance;
-    if (scrollDown) camera.position.y += scrollDistance;
-
-    updateBoids(static_cast<float>(frameInfo.deltaTime));
-
-    canvas.clear();
-    for (const Boid& boid : boids) {
-      drawBoid(boid);
-    }
-  }
-
- private:
-  void updateBoids(float deltaTime) {
-    std::vector<glm::vec2> accelerations(boids.size());
-
-    for (size_t i = 0; i < boids.size(); ++i) {
-      glm::vec2 separation{0.0f};
-      glm::vec2 averageVelocity{0.0f};
-      glm::vec2 averagePosition{0.0f};
-      int neighborCount = 0;
-
-      for (size_t j = 0; j < boids.size(); ++j) {
-        if (i == j) continue;
-
-        glm::vec2 offset = boids[i].position - boids[j].position;
-        float dist = glm::length(offset);
-        if (dist >= PERCEPTION_RADIUS) continue;
-
-        averageVelocity += boids[j].velocity;
-        averagePosition += boids[j].position;
-        ++neighborCount;
-
-        if (dist > 0.0f && dist < SEPARATION_RADIUS) {
-          separation += offset / (dist * dist);
-        }
-      }
-
-      glm::vec2 acceleration =
-          steerTowards(boids[i], separation) * SEPARATION_WEIGHT;
-
-      if (neighborCount > 0) {
-        averageVelocity /= static_cast<float>(neighborCount);
-        acceleration +=
-            steerTowards(boids[i], averageVelocity) * ALIGNMENT_WEIGHT;
-
-        averagePosition /= static_cast<float>(neighborCount);
-        glm::vec2 towardsGroup = averagePosition - boids[i].position;
-        acceleration += steerTowards(boids[i], towardsGroup) * COHESION_WEIGHT;
-      }
-
-      accelerations[i] = acceleration;
-    }
-
-    for (size_t i = 0; i < boids.size(); ++i) {
-      Boid& boid = boids[i];
-      boid.velocity += accelerations[i] * deltaTime;
-
-      float speed = glm::length(boid.velocity);
-      if (speed > MAX_SPEED) {
-        boid.velocity = boid.velocity / speed * MAX_SPEED;
-      }
-
-      boid.position += boid.velocity * deltaTime;
-      wrapPosition(boid.position);
-    }
-  }
-
-  // Steers boid towards desiredDirection at up to MAX_SPEED, clamped to
-  // MAX_FORCE.
-  glm::vec2 steerTowards(const Boid& boid, glm::vec2 desiredDirection) {
-    float directionLength = glm::length(desiredDirection);
-    if (directionLength < 1e-5f) return glm::vec2{0.0f};
-
-    glm::vec2 desired = desiredDirection / directionLength * MAX_SPEED;
-    glm::vec2 steer = desired - boid.velocity;
-
-    float steerLength = glm::length(steer);
-    if (steerLength > MAX_FORCE) {
-      steer = steer / steerLength * MAX_FORCE;
-    }
-    return steer;
-  }
-
-  void wrapPosition(glm::vec2& position) {
-    if (position.x > WORLD_HALF_WIDTH) position.x = -WORLD_HALF_WIDTH;
-    if (position.x < -WORLD_HALF_WIDTH) position.x = WORLD_HALF_WIDTH;
-    if (position.y > WORLD_HALF_HEIGHT) position.y = -WORLD_HALF_HEIGHT;
-    if (position.y < -WORLD_HALF_HEIGHT) position.y = WORLD_HALF_HEIGHT;
-  }
-
-  void drawBoid(const Boid& boid) {
-    constexpr float LENGTH = 20.0f;
-    constexpr float WIDTH = 12.0f;
-
-    glm::vec2 direction = boid.velocity;
-    float speed = glm::length(direction);
-    direction = speed > 1e-5f ? direction / speed : glm::vec2{0.0f, -1.0f};
-    glm::vec2 perpendicular{-direction.y, direction.x};
-
-    glm::vec2 nose = boid.position + direction * (LENGTH * 0.5f);
-    glm::vec2 tailLeft = boid.position - direction * (LENGTH * 0.5f) +
-                         perpendicular * (WIDTH * 0.5f);
-    glm::vec2 tailRight = boid.position - direction * (LENGTH * 0.5f) -
-                          perpendicular * (WIDTH * 0.5f);
-
-    canvas.triangle(nose, tailLeft, tailRight, {1.0f, 1.0f, 1.0f});
-  }
-
-  void setScrollKeyHeld(sophia::KeyCode keycode, bool held) {
-    if (keycode == sophia::Key::Left) scrollLeft = held;
-    if (keycode == sophia::Key::Right) scrollRight = held;
-    if (keycode == sophia::Key::Up) scrollUp = held;
-    if (keycode == sophia::Key::Down) scrollDown = held;
-  }
-
-  std::vector<Boid> boids;
-  bool scrollLeft = false;
-  bool scrollRight = false;
-  bool scrollUp = false;
-  bool scrollDown = false;
 };
 
 SOPHIA_MAIN(Testbed)