Supporting setting panel layout

editor/panels/asset_browser_panel.cpp

@@ -3,8 +3,6 @@
 #include <imgui.h>
 
 void AssetBrowserPanel::onUpdate(const sophia::FrameInfo&) {
-  ImGui::Begin("Asset Browser");
-
   ImGui::BeginChild("Folders", ImVec2(150, 0), true);
   for (int i = 0; i < static_cast<int>(folders.size()); i++) {
     if (ImGui::Selectable(folders[static_cast<size_t>(i)].name.c_str(),
@@ -22,6 +20,4 @@ void AssetBrowserPanel::onUpdate(const sophia::FrameInfo&) {
     ImGui::Selectable(file.c_str());
   }
   ImGui::EndChild();
-
-  ImGui::End();
 }

editor/panels/asset_browser_panel.hpp

@@ -7,7 +7,7 @@
 
 class AssetBrowserPanel : public sophia::Panel {
  public:
-  AssetBrowserPanel() : Panel{"Asset Browser"} {}
+  AssetBrowserPanel() : Panel{{.name = "Asset Browser"}} {}
 
   void onUpdate(const sophia::FrameInfo& frameInfo) override;
 

editor/panels/inspector_panel.cpp

@@ -5,8 +5,6 @@
 #include <cstdio>
 
 void InspectorPanel::onUpdate(const sophia::FrameInfo&) {
-  ImGui::Begin("Inspector");
-
   char nameBuf[128];
   std::snprintf(nameBuf, sizeof(nameBuf), "%s", name.c_str());
   if (ImGui::InputText("Name", nameBuf, sizeof(nameBuf))) {
@@ -31,6 +29,4 @@ void InspectorPanel::onUpdate(const sophia::FrameInfo&) {
   if (ImGui::CollapsingHeader("Script", ImGuiTreeNodeFlags_DefaultOpen)) {
     ImGui::Text("%s", scriptName.c_str());
   }
-
-  ImGui::End();
 }

editor/panels/inspector_panel.hpp

@@ -7,7 +7,7 @@
 
 class InspectorPanel : public sophia::Panel {
  public:
-  InspectorPanel() : Panel{"Inspector"} {}
+  InspectorPanel() : Panel{{.name = "Inspector"}} {}
 
   void onUpdate(const sophia::FrameInfo& frameInfo) override;
 

editor/panels/scene_hierarchy_panel.cpp

@@ -26,9 +26,7 @@ void SceneHierarchyPanel::drawNode(const Node& node) {
 }
 
 void SceneHierarchyPanel::onUpdate(const sophia::FrameInfo&) {
-  ImGui::Begin("Scene Hierarchy");
   for (const Node& node : nodes) {
     drawNode(node);
   }
-  ImGui::End();
 }

editor/panels/scene_hierarchy_panel.hpp

@@ -7,7 +7,7 @@
 
 class SceneHierarchyPanel : public sophia::Panel {
  public:
-  SceneHierarchyPanel() : Panel{"Scene Hierarchy"} {}
+  SceneHierarchyPanel() : Panel{{.name = "Scene Hierarchy"}} {}
 
   void onUpdate(const sophia::FrameInfo& frameInfo) override;
 

editor/panels/viewport_panel.cpp

@@ -0,0 +1,45 @@
+#include "viewport_panel.hpp"
+
+#include <imgui.h>
+
+void ViewportPanel::onUpdate(const sophia::FrameInfo&) {
+  const struct {
+    const char* label;
+    GizmoMode mode;
+  } modes[] = {{"Move", GizmoMode::Move},
+               {"Rotate", GizmoMode::Rotate},
+               {"Scale", GizmoMode::Scale}};
+
+  for (const auto& entry : modes) {
+    if (ImGui::RadioButton(entry.label, gizmoMode == entry.mode)) {
+      gizmoMode = entry.mode;
+    }
+    ImGui::SameLine();
+  }
+  ImGui::Checkbox("Grid", &showGrid);
+
+  ImGui::Separator();
+
+  const ImVec2 origin = ImGui::GetCursorScreenPos();
+  const ImVec2 size = ImGui::GetContentRegionAvail();
+  const ImVec2 end(origin.x + size.x, origin.y + size.y);
+
+  ImDrawList* drawList = ImGui::GetWindowDrawList();
+  drawList->AddRectFilled(origin, end, IM_COL32(24, 26, 32, 255));
+
+  if (showGrid) {
+    constexpr float GRID_STEP = 40.0f;
+    const ImU32 gridColor = IM_COL32(255, 255, 255, 18);
+    for (float x = GRID_STEP; x < size.x; x += GRID_STEP) {
+      drawList->AddLine(ImVec2(origin.x + x, origin.y),
+                        ImVec2(origin.x + x, end.y), gridColor);
+    }
+    for (float y = GRID_STEP; y < size.y; y += GRID_STEP) {
+      drawList->AddLine(ImVec2(origin.x, origin.y + y),
+                        ImVec2(end.x, origin.y + y), gridColor);
+    }
+  }
+
+  ImGui::SetCursorScreenPos(ImVec2(origin.x + 8.0f, origin.y + 8.0f));
+  ImGui::TextDisabled("%.0f x %.0f", size.x, size.y);
+}

editor/panels/viewport_panel.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <sophia/frame_info.hpp>
+#include <sophia/ui/panel.hpp>
+
+class ViewportPanel : public sophia::Panel {
+ public:
+  ViewportPanel() : Panel{{.name = "Viewport"}} {}
+
+  void onUpdate(const sophia::FrameInfo& frameInfo) override;
+
+ private:
+  enum class GizmoMode { Move, Rotate, Scale };
+
+  GizmoMode gizmoMode = GizmoMode::Move;
+  bool showGrid = true;
+};