Supporting setting panel layout

engine/include/sophia/ui/dock_layout.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+namespace sophia {
+
+struct DockLayout {
+  float leftWidth = 0.2f;
+  float rightWidth = 0.25f;
+  float bottomHeight = 0.25f;
+
+  std::vector<std::string> left;
+  std::vector<std::string> right;
+  std::vector<std::string> bottom;
+  std::vector<std::string> center;
+
+  bool empty() const {
+    return left.empty() && right.empty() && bottom.empty() && center.empty();
+  }
+};
+
+}  // namespace sophia

engine/include/sophia/ui/panel.hpp

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <glm/glm.hpp>
+#include <optional>
 #include <sophia/frame_info.hpp>
 #include <string>
 #include <utility>
@@ -8,28 +10,46 @@ namespace sophia {
 
 class Panel {
  public:
+  struct Config {
+    std::string name;
+
+    // Locked panels can't be moved, resized, docked, collapsed or closed.
+    bool locked = false;
+    bool closable = true;
+
+    // A zero component lets ImGui size the window. Applied on first use, or
+    // every frame when locked.
+    glm::vec2 size{0.0f, 0.0f};
+    std::optional<glm::vec2> position;
+  };
+
   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)} {}
+  explicit Panel(Config config) : config{std::move(config)} {}
   virtual ~Panel() = default;
 
-  virtual void onUpdate(const FrameInfo& frameInfo) = 0;
+  // Owns the ImGui window: Begin, onUpdate, End.
+  void draw(const FrameInfo& frameInfo);
 
-  const std::string& getName() const { return name; }
+  const std::string& getName() const { return config.name; }
+  bool isLocked() const { return config.locked; }
 
   bool isVisible() const { return this->visible; }
   void setVisible(bool visible) { this->visible = visible; }
   void toggleVisible() { this->visible = !this->visible; }
 
  protected:
+  // Draw the panel's contents; the window is already open.
+  virtual void onUpdate(const FrameInfo& frameInfo) = 0;
+
   bool visible = true;
 
  private:
-  std::string name;
+  Config config;
 };
 
 }  // namespace sophia

engine/include/sophia/ui/panel_registry.hpp

@@ -3,6 +3,7 @@
 #include <memory>
 #include <sophia/frame_info.hpp>
 #include <sophia/handles.hpp>
+#include <sophia/ui/dock_layout.hpp>
 #include <sophia/ui/panel.hpp>
 #include <sophia/util/assert.hpp>
 #include <string_view>
@@ -94,6 +95,11 @@ class PanelRegistry {
 
   void update(const FrameInfo& frameInfo);
 
+  void setDefaultLayout(DockLayout layout) {
+    defaultLayout = std::move(layout);
+  }
+  const DockLayout& getDefaultLayout() const { return defaultLayout; }
+
  private:
   struct Slot {
     std::unique_ptr<Panel> panel;
@@ -102,6 +108,7 @@ class PanelRegistry {
 
   std::vector<Slot> slots;
   std::vector<u32> freeList;
+  DockLayout defaultLayout;
 };
 
 }  // namespace sophia

engine/src/application.cpp

@@ -57,7 +57,16 @@ class Application::Impl {
     ImGuiRenderer imguiRenderer{window, device, renderContext.getImageFormat(),
                                 renderContext.getImageCount()};
 
+    this->application.consoleCommandRegistry.registerCommand(
+        "reset_layout", "Restore the default panel layout",
+        [&imguiRenderer](const std::vector<std::string>&) {
+          imguiRenderer.resetLayout();
+          return std::string{"Layout reset"};
+        });
+
     this->application.onCreate();
+    imguiRenderer.setDefaultLayout(
+        this->application.panelRegistry.getDefaultLayout());
 
     auto startTime = std::chrono::high_resolution_clock::now();
     auto currentTime = startTime;

engine/src/imgui_renderer.cpp

@@ -3,9 +3,21 @@
 #include <imgui.h>
 #include <imgui_impl_glfw.h>
 #include <imgui_impl_vulkan.h>
+#include <imgui_internal.h>  // DockBuilder API
 
 namespace sophia {
 
+namespace {
+constexpr ImGuiDockNodeFlags DOCKSPACE_FLAGS =
+    ImGuiDockNodeFlags_PassthruCentralNode;
+
+void dockAll(const std::vector<std::string>& windows, ImGuiID nodeId) {
+  for (const std::string& name : windows) {
+    ImGui::DockBuilderDockWindow(name.c_str(), nodeId);
+  }
+}
+}  // namespace
+
 ImGuiRenderer::ImGuiRenderer(Window& window, Device& device,
                              vk::Format colorAttachmentFormat,
                              u32 minImageCount) {
@@ -65,8 +77,59 @@ void ImGuiRenderer::beginFrame() {
   ImGui_ImplGlfw_NewFrame();
   ImGui::NewFrame();
 
-  ImGui::DockSpaceOverViewport(0, ImGui::GetMainViewport(),
-                               ImGuiDockNodeFlags_PassthruCentralNode);
+  ImGuiID dockspaceId = ImGui::DockSpaceOverViewport(
+      0, ImGui::GetMainViewport(), DOCKSPACE_FLAGS);
+  applyLayoutIfNeeded(dockspaceId, DOCKSPACE_FLAGS);
+}
+
+void ImGuiRenderer::setDefaultLayout(DockLayout layout) {
+  defaultLayout = std::move(layout);
+  seedIfUnsaved = true;
+}
+
+void ImGuiRenderer::resetLayout() { forceReset = true; }
+
+void ImGuiRenderer::applyLayoutIfNeeded(ImGuiID dockspaceId,
+                                        ImGuiDockNodeFlags flags) {
+  if (defaultLayout.empty()) {
+    return;
+  }
+
+  bool apply = forceReset;
+  if (seedIfUnsaved) {
+    // A layout restored from imgui.ini shows up as a split root node.
+    ImGuiDockNode* root = ImGui::DockBuilderGetNode(dockspaceId);
+    apply = apply || root == nullptr || !root->IsSplitNode();
+    seedIfUnsaved = false;
+  }
+  if (!apply) {
+    return;
+  }
+  forceReset = false;
+
+  const ImVec2 size = ImGui::GetMainViewport()->Size;
+
+  ImGui::DockBuilderRemoveNode(dockspaceId);
+  ImGui::DockBuilderAddNode(dockspaceId, flags | ImGuiDockNodeFlags_DockSpace);
+  ImGui::DockBuilderSetNodeSize(dockspaceId, size);
+
+  ImGuiID center = dockspaceId;
+  const ImGuiID left = ImGui::DockBuilderSplitNode(
+      center, ImGuiDir_Left, defaultLayout.leftWidth, nullptr, &center);
+  // The right split is taken from what's left after the left split.
+  const float rightRatio =
+      defaultLayout.rightWidth / (1.0f - defaultLayout.leftWidth);
+  const ImGuiID right = ImGui::DockBuilderSplitNode(
+      center, ImGuiDir_Right, rightRatio, nullptr, &center);
+  const ImGuiID bottom = ImGui::DockBuilderSplitNode(
+      center, ImGuiDir_Down, defaultLayout.bottomHeight, nullptr, &center);
+
+  dockAll(defaultLayout.left, left);
+  dockAll(defaultLayout.right, right);
+  dockAll(defaultLayout.bottom, bottom);
+  dockAll(defaultLayout.center, center);
+
+  ImGui::DockBuilderFinish(dockspaceId);
 }
 
 void ImGuiRenderer::endFrame(vk::CommandBuffer commandBuffer) {

engine/src/imgui_renderer.hpp

@@ -1,6 +1,9 @@
 #pragma once
 
+#include <imgui.h>
+
 #include <sophia/types.hpp>
+#include <sophia/ui/dock_layout.hpp>
 
 #include "device.hpp"
 #include "window.hpp"
@@ -18,6 +21,19 @@ class ImGuiRenderer {
 
   void beginFrame();
   void endFrame(vk::CommandBuffer commandBuffer);
+
+  // Seeds the layout on the next frame, but only if no saved layout exists.
+  void setDefaultLayout(DockLayout layout);
+
+  // Discards the current layout and re-applies the default on the next frame.
+  void resetLayout();
+
+ private:
+  void applyLayoutIfNeeded(ImGuiID dockspaceId, ImGuiDockNodeFlags flags);
+
+  DockLayout defaultLayout;
+  bool seedIfUnsaved = false;
+  bool forceReset = false;
 };
 
 }  // namespace sophia

engine/src/ui/panel.cpp

@@ -0,0 +1,35 @@
+#include <imgui.h>
+
+#include <sophia/ui/panel.hpp>
+
+namespace sophia {
+
+void Panel::draw(const FrameInfo& frameInfo) {
+  ImGuiWindowFlags flags = ImGuiWindowFlags_None;
+  if (config.locked) {
+    flags |= ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize |
+             ImGuiWindowFlags_NoDocking | ImGuiWindowFlags_NoCollapse;
+  }
+
+  const ImGuiCond cond =
+      config.locked ? ImGuiCond_Always : ImGuiCond_FirstUseEver;
+  if (config.size.x > 0.0f || config.size.y > 0.0f) {
+    ImGui::SetNextWindowSize(ImVec2(config.size.x, config.size.y), cond);
+  }
+  if (config.position) {
+    ImGui::SetNextWindowPos(ImVec2(config.position->x, config.position->y),
+                            cond);
+  }
+
+  bool open = true;
+  const bool showCloseButton = config.closable && !config.locked;
+  ImGui::Begin(config.name.c_str(), showCloseButton ? &open : nullptr, flags);
+  onUpdate(frameInfo);
+  ImGui::End();
+
+  if (!open) {
+    visible = false;
+  }
+}
+
+}  // namespace sophia

engine/src/ui/panel_registry.cpp

@@ -80,7 +80,7 @@ u32 PanelRegistry::visibleCount() const {
 void PanelRegistry::update(const FrameInfo& frameInfo) {
   for (auto& slot : slots) {
     if (slot.panel && slot.panel->isVisible()) {
-      slot.panel->onUpdate(frameInfo);
+      slot.panel->draw(frameInfo);
     }
   }
 }

engine/src/ui/panels/console_panel.cpp

@@ -111,8 +111,6 @@ int ConsolePanel::textEditCallback(ImGuiInputTextCallbackData* data) {
 }
 
 void ConsolePanel::onUpdate(const FrameInfo&) {
-  ImGui::Begin("Console");
-
   if (ImGui::SmallButton("Clear")) {
     clear();
   }
@@ -161,8 +159,6 @@ void ConsolePanel::onUpdate(const FrameInfo&) {
   if (reclaimFocus) {
     ImGui::SetKeyboardFocusHere(-1);
   }
-
-  ImGui::End();
 }
 
 }  // namespace sophia

engine/src/ui/panels/console_panel.hpp

@@ -13,7 +13,7 @@ namespace sophia {
 class ConsolePanel : public Panel {
  public:
   explicit ConsolePanel(ConsoleCommandRegistry& consoleCommandRegistry)
-      : Panel{"Console"}, consoleCommandRegistry{consoleCommandRegistry} {
+      : Panel{{.name = "Console"}}, consoleCommandRegistry{consoleCommandRegistry} {
     log("Console ready. Type 'help' for a list of commands.");
   }
 

engine/src/ui/panels/ecs_inspector_panel.cpp

@@ -7,8 +7,6 @@
 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);
@@ -50,8 +48,6 @@ void EcsInspectorPanel::onUpdate(const FrameInfo&) {
   } else {
     ImGui::TextDisabled("No entity selected");
   }
-
-  ImGui::End();
 }
 
 }  // namespace sophia

engine/src/ui/panels/ecs_inspector_panel.hpp

@@ -10,7 +10,7 @@ namespace sophia {
 class EcsInspectorPanel : public Panel {
  public:
   explicit EcsInspectorPanel(entt::registry& registry)
-      : Panel{"ECS Inspector"}, registry{registry} {}
+      : Panel{{.name = "ECS Inspector"}}, registry{registry} {}
 
   void onUpdate(const FrameInfo& frameInfo) override;
 

engine/src/ui/panels/frame_stats_panel.hpp

@@ -9,7 +9,7 @@ namespace sophia {
 
 class FrameStatsPanel : public Panel {
  public:
-  FrameStatsPanel() : Panel{"Frame Stats"} {}
+  FrameStatsPanel() : Panel{{.name = "Frame Stats"}} {}
 
   void onUpdate(const FrameInfo& frameInfo) override {
     frameCount++;
@@ -25,10 +25,8 @@ class FrameStatsPanel : public Panel {
       nextRefreshTime = frameInfo.elapsedTime + REFRESH_INTERVAL;
     }
 
-    ImGui::Begin("Frame Stats");
     ImGui::Text("FPS: %.1f", displayedFps);
     ImGui::Text("Frame time: %.3f ms", displayedFrameTimeMs);
-    ImGui::End();
   }
 
  private:

engine/src/ui/panels/panel_registry_panel.cpp

@@ -5,7 +5,6 @@
 namespace sophia {
 
 void PanelRegistryPanel::onUpdate(const FrameInfo&) {
-  ImGui::Begin("PanelRegistry");
   ImGui::Text("%u panels (%u visible)", registry.size(),
               registry.visibleCount());
   ImGui::Separator();
@@ -21,8 +20,6 @@ void PanelRegistryPanel::onUpdate(const FrameInfo&) {
       panel->setVisible(visible);
     }
   }
-
-  ImGui::End();
 }
 
 }  // namespace sophia

engine/src/ui/panels/panel_registry_panel.hpp

@@ -9,7 +9,7 @@ namespace sophia {
 class PanelRegistryPanel : public Panel {
  public:
   explicit PanelRegistryPanel(PanelRegistry& registry)
-      : Panel{"PanelRegistry"}, registry{registry} {}
+      : Panel{{.name = "PanelRegistry"}}, registry{registry} {}
 
   void onUpdate(const FrameInfo& frameInfo) override;