PIE: viewport-embedded playback with UE-style main toolbar

Play no longer switches to fullscreen direct rendering: PIE now keeps
the editor UI alive and renders the primary camera into the Viewport
panel (new SceneRenderer::SetGameView flag; kDisplayDirect stays a
manual fullscreen preview for later release form). Editor camera stops
being driven during PIE, and viewport click-pick is gated off while
playing (clicks are game input now).

The Play/Stop buttons move out of the menu bar into a dedicated main
toolbar row below it (centered, UE Main Toolbar semantics): green Play
when idle; Pause (yellow, highlighted while paused) + Stop (orange)
while playing. Ctrl+P hotkey kept. Stats "Pause Simulation" merged
into the toolbar Pause; viewport overlay shows PAUSED accordingly.

App/editor/Editor.cpp

@@ -40,8 +40,9 @@ Editor::~Editor() = default;
 void Editor::Init(const EditorContext& ctx)
 {
     m_Ctx = ctx;
-    // PIE 运行态指针：指向本对象成员（ctx 拷贝后补接，面板只读）
+    // PIE 运行/暂停态指针：指向本对象成员（ctx 拷贝后补接，面板只读）
     m_Ctx.playState = &m_Playing;
+    m_Ctx.pausedState = &m_Paused;
 
     m_Hierarchy = std::make_unique<HierarchyPanel>();
     m_Inspector = std::make_unique<InspectorPanel>();
@@ -78,7 +79,9 @@ void Editor::Init(const EditorContext& ctx)
 
 // ---- PIE（Play-In-Editor）----
 
-// Play：当前场景 → 内存 YAML 快照 → 切游戏渲染（primary 相机实体）
+// Play：当前场景 → 内存 YAML 快照 → 切 gameView（Viewport 面板内嵌
+// primary 相机渲染，UE PIE 语义——编辑器 UI 保持可用，不切全屏；
+// kDisplayDirect 全屏预览是后期发布形态，手动经 Stats 切换）
 // → 解冻时间（物理/脚本/动画开始跑）。快照失败不进 Play（现场不动）
 void Editor::DoPlay()
 {
@@ -93,7 +96,9 @@ void Editor::DoPlay()
     }
 
     m_Playing = true;
-    m_Ctx.renderer->SetDisplayMode(kDisplayDirect);
+    m_Paused = false;
+    m_Gizmo.dragging = false;   // 编辑态拖杆中点 Play：杆运行态不出，复位
+    m_Ctx.renderer->SetGameView(true);
     Time::SetTimeScale(1.0f);
     ENGINE_INFO("PIE: playing (scene snapshot {} bytes)",
                 m_PlaySnapshot.size());
@@ -117,7 +122,8 @@ void Editor::DoStop()
     m_PlaySnapshot.clear();
 
     m_Playing = false;
-    m_Ctx.renderer->SetDisplayMode(kDisplayViewport);
+    m_Paused = false;
+    m_Ctx.renderer->SetGameView(false);
     Time::SetTimeScale(0.0f);
     SelectEntity(entt::null);
     m_Gizmo.dragging = false;
@@ -129,6 +135,14 @@ void Editor::TogglePlay()
     m_Playing ? DoStop() : DoPlay();
 }
 
+// PIE 暂停（UE Pause 语义）：timeScale 0 ↔ 1。运行态才有意义
+//（编辑器态本来就冻结，Pause 按钮不出现）
+void Editor::TogglePause()
+{
+    m_Paused = !m_Paused;
+    Time::SetTimeScale(m_Paused ? 0.0f : 1.0f);
+}
+
 void Editor::Draw()
 {
     // ImGuizmo 每帧首调（官方约定）：内部会清 mbOverGizmoHotspot 等
@@ -154,6 +168,7 @@ void Editor::Draw()
     ImGui::PopStyleVar(3);
 
     DrawMenuBar();
+    DrawToolbar();
     DrawDockSpace();
 
     ImGui::End();
@@ -227,42 +242,6 @@ void Editor::DrawMenuBar()
         return;
     }
 
-    // ---- PIE 工具栏（UE 主工具栏语义）：Play/Stop 切换按钮 +
-    // Ctrl+P 全局热键。运行态按钮变 Stop（黄底提示在视口内）----
-    {
-        const ImGuiIO& io = ImGui::GetIO();
-        // Ctrl+P：文本输入中（改名/路径框）不触发，防打字误切 PIE
-        if (!m_Playing && io.KeyCtrl && !io.WantTextInput &&
-            ImGui::IsKeyPressed(ImGuiKey_P, false))
-        {
-            TogglePlay();
-        }
-
-        if (m_Playing)
-        {
-            ImGui::PushStyleColor(ImGuiCol_Button,
-                                  ImVec4(0.75f, 0.45f, 0.10f, 1.0f));
-            ImGui::PushStyleColor(ImGuiCol_ButtonHovered,
-                                  ImVec4(0.85f, 0.55f, 0.15f, 1.0f));
-            ImGui::PushStyleColor(ImGuiCol_ButtonActive,
-                                  ImVec4(0.90f, 0.62f, 0.20f, 1.0f));
-            if (ImGui::SmallButton("Stop (Ctrl+P)"))
-            {
-                TogglePlay();
-            }
-            ImGui::PopStyleColor(3);
-            ImGui::SameLine();
-            ImGui::TextColored(ImVec4(1.0f, 0.72f, 0.25f, 1.0f),
-                               "PLAYING - editor input disabled");
-        }
-        else if (ImGui::SmallButton("Play (Ctrl+P)"))
-        {
-            TogglePlay();
-        }
-        ImGui::SameLine();
-        ImGui::Separator();
-    }
-
     if (ImGui::BeginMenu("File"))
     {
         // 运行态禁存取：Save 会把"玩出来的状态"当编辑结果落盘，
@@ -298,6 +277,98 @@ void Editor::DrawMenuBar()
     ImGui::EndMenuBar();
 }
 
+// 主工具栏（UE Main Toolbar 语义）：菜单栏下方独立一行，Play 组水平
+// 居中。编辑态 = [Play]（绿）；PIE 运行态 = [Pause][Stop]（暂停高亮黄 /
+// 停止橙红）。kDisplayDirect 全屏预览是发布形态预览，不在此处
+void Editor::DrawToolbar()
+{
+    const ImGuiIO& io = ImGui::GetIO();
+    // Ctrl+P：文本输入中（改名/路径框）不触发，防打字误切 PIE
+    if (!m_Playing && io.KeyCtrl && !io.WantTextInput &&
+        ImGui::IsKeyPressed(ImGuiKey_P, false))
+    {
+        TogglePlay();
+    }
+
+    // 按钮加大触感（工具栏行高 = 一个按钮高；DockSpace avail 自适应）
+    ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(12.0f, 4.0f));
+    const ImGuiStyle& st = ImGui::GetStyle();
+
+    // Play 组宽度 → 水平居中（编辑态 1 钮 / 运行态 2 钮）
+    float groupW = 0.0f;
+    if (m_Playing)
+    {
+        groupW = ImGui::CalcTextSize("Pause").x + ImGui::CalcTextSize("Stop").x +
+                 4.0f * st.FramePadding.x + st.ItemSpacing.x;
+    }
+    else
+    {
+        groupW = ImGui::CalcTextSize("Play").x + 2.0f * st.FramePadding.x;
+    }
+    ImGui::SetCursorPosX((ImGui::GetWindowWidth() - groupW) * 0.5f);
+
+    if (m_Playing)
+    {
+        // Pause：暂停中亮黄常驻（UE 按下态），运行中暗黄
+        ImGui::PushStyleColor(ImGuiCol_Button,
+            m_Paused ? ImVec4(0.85f, 0.62f, 0.12f, 1.0f)
+                     : ImVec4(0.55f, 0.42f, 0.10f, 1.0f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonHovered,
+            m_Paused ? ImVec4(0.92f, 0.70f, 0.18f, 1.0f)
+                     : ImVec4(0.65f, 0.50f, 0.14f, 1.0f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonActive,
+                              ImVec4(0.95f, 0.76f, 0.24f, 1.0f));
+        if (ImGui::Button("Pause"))
+        {
+            TogglePause();
+        }
+        ImGui::PopStyleColor(3);
+        if (ImGui::IsItemHovered())
+        {
+            ImGui::SetTooltip(m_Paused ? "Resume simulation"
+                                       : "Pause simulation");
+        }
+
+        ImGui::SameLine();
+        // Stop：橙红（沿用视口 PLAYING 提示色系）
+        ImGui::PushStyleColor(ImGuiCol_Button,
+                              ImVec4(0.75f, 0.45f, 0.10f, 1.0f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonHovered,
+                              ImVec4(0.85f, 0.55f, 0.15f, 1.0f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonActive,
+                              ImVec4(0.90f, 0.62f, 0.20f, 1.0f));
+        if (ImGui::Button("Stop"))
+        {
+            TogglePlay();
+        }
+        ImGui::PopStyleColor(3);
+        if (ImGui::IsItemHovered())
+        {
+            ImGui::SetTooltip("Stop and restore editor scene (Ctrl+P)");
+        }
+    }
+    else
+    {
+        // Play：绿（UE Play 按钮语义）
+        ImGui::PushStyleColor(ImGuiCol_Button,
+                              ImVec4(0.22f, 0.48f, 0.26f, 1.0f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonHovered,
+                              ImVec4(0.28f, 0.58f, 0.32f, 1.0f));
+        ImGui::PushStyleColor(ImGuiCol_ButtonActive,
+                              ImVec4(0.34f, 0.66f, 0.38f, 1.0f));
+        if (ImGui::Button("Play"))
+        {
+            TogglePlay();
+        }
+        ImGui::PopStyleColor(3);
+        if (ImGui::IsItemHovered())
+        {
+            ImGui::SetTooltip("Play in editor (Ctrl+P)");
+        }
+    }
+    ImGui::PopStyleVar();
+}
+
 void Editor::DrawDockSpace()
 {
     const ImGuiID dockspaceId = ImGui::GetID("EditorDockSpace");