Smooth battle zone camera transitions

game/docs/planning/game_architecture_board.md

@@ -178,7 +178,7 @@ mindmap
 
 - `scene/whitebox_scene.*`
 - `scene/camera_controller.*`：玩家跟随、dead zone、平滑和世界边界 clamp。
-- `CameraZoneLock`：玩家进入 battle zone 后摄像机锁定到 zone camera bounds，锁定范围会防御性保证不小于视口，当前用 `F2` 或离开 zone 做 debug 清场解锁。
+- `CameraZoneLock`：玩家进入 battle zone 后摄像机平滑切换到 zone camera bounds，可移动锁定范围会防御性保证不小于视口，当前用 `F2` 或离开 zone 做 debug 清场解锁。
 
 下一步：
 

game/docs/planning/scene_build_plan.md

@@ -24,6 +24,7 @@
 - `CameraController` 已接入：修复场景 `OnUpdate()` 不被调用导致摄像机不动的问题，并提供跟随、dead zone、平滑和世界边界 clamp。
 - `CameraZoneLock` 已接入：玩家进入 battle zone 后摄像机临时锁定到 zone camera bounds，`F2` 临时清场并恢复全关卡跟随。
 - 已修复 zone camera bounds 小于 1280 视口导致摄像机锁死的问题；所有锁镜头范围必须不小于当前视口，debug 阶段玩家离开 zone 会自动清场解锁。
+- 已修复进入 battle zone 时摄像机硬切的问题；zone camera bounds 表示摄像机可移动范围，进入/离开 zone 都通过短过渡平滑切换约束。
 
 ## 2. 第一关场景目标
 

game/src/data/whitebox_level.cpp

@@ -112,17 +112,17 @@ LevelDefinition CreateWhiteboxLevel() {
   level.battleZones = {
       {"zone_01_intro",
        frostbite2D::Rect(520.0f, 260.0f, 560.0f, 340.0f),
-       frostbite2D::Rect(320.0f, 0.0f, 1280.0f, 720.0f),
+       frostbite2D::Rect(0.0f, 0.0f, 1940.0f, 720.0f),
        {{"zone_01_enemy_a", frostbite2D::Vec2(760.0f, 560.0f)},
         {"zone_01_enemy_b", frostbite2D::Vec2(980.0f, 560.0f)}}},
       {"zone_02_platform",
        frostbite2D::Rect(1420.0f, 250.0f, 680.0f, 350.0f),
-       frostbite2D::Rect(1280.0f, 0.0f, 1280.0f, 720.0f),
+       frostbite2D::Rect(660.0f, 0.0f, 2300.0f, 720.0f),
        {{"zone_02_enemy_a", frostbite2D::Vec2(1620.0f, 560.0f)},
         {"zone_02_enemy_b", frostbite2D::Vec2(1900.0f, 560.0f)}}},
       {"zone_03_exit",
        frostbite2D::Rect(2380.0f, 250.0f, 720.0f, 350.0f),
-       frostbite2D::Rect(1920.0f, 0.0f, 1280.0f, 720.0f),
+       frostbite2D::Rect(1600.0f, 0.0f, 1600.0f, 720.0f),
        {{"zone_03_enemy_a", frostbite2D::Vec2(2580.0f, 560.0f)},
         {"zone_03_enemy_b", frostbite2D::Vec2(2860.0f, 560.0f)}}},
   };

game/src/scene/whitebox_scene.cpp

@@ -6,6 +6,7 @@
 #include <frostbite2D/event/key_event.h>
 #include <frostbite2D/graphics/camera.h>
 #include <frostbite2D/graphics/renderer.h>
+#include <algorithm>
 
 namespace ns_game {
 
@@ -26,6 +27,7 @@ void WhiteboxScene::onEnter() {
 void WhiteboxScene::Update(float deltaTime) {
   frostbite2D::Scene::Update(deltaTime);
   updateBattleZones();
+  updateCameraBoundsBlend(deltaTime);
   updateCamera(deltaTime);
 }
 
@@ -93,6 +95,7 @@ void WhiteboxScene::configureCamera() {
   config.viewportWidth = static_cast<float>(config::kVirtualWidth);
   config.viewportHeight = static_cast<float>(config::kVirtualHeight);
   cameraController_.Configure(config);
+  currentCameraBounds_ = level_.cameraBounds;
 
   if (player_) {
     cameraController_.SnapToTarget(*camera, player_->GetWorldBounds());
@@ -111,6 +114,14 @@ void WhiteboxScene::toggleDebugOverlay() {
   debugFlags_.showSpawnPoints = enabled;
 }
 
+void WhiteboxScene::beginCameraBoundsBlend(
+    const frostbite2D::Rect& targetBounds) {
+  cameraBoundsBlendStart_ = currentCameraBounds_;
+  cameraBoundsBlendTarget_ = targetBounds;
+  cameraBoundsBlendTimer_ = 0.0f;
+  cameraBoundsBlendActive_ = true;
+}
+
 void WhiteboxScene::clearActiveBattleZone() {
   if (activeBattleZoneIndex_ < 0 ||
       activeBattleZoneIndex_ >= static_cast<int>(battleZoneStates_.size())) {
@@ -119,7 +130,34 @@ void WhiteboxScene::clearActiveBattleZone() {
 
   battleZoneStates_[static_cast<size_t>(activeBattleZoneIndex_)].cleared = true;
   activeBattleZoneIndex_ = -1;
-  cameraController_.SetWorldBounds(level_.cameraBounds);
+  beginCameraBoundsBlend(level_.cameraBounds);
+}
+
+void WhiteboxScene::updateCameraBoundsBlend(float deltaTime) {
+  if (!cameraBoundsBlendActive_) {
+    return;
+  }
+
+  cameraBoundsBlendTimer_ += deltaTime;
+  const float t = cameraBoundsBlendDuration_ > 0.0f
+                      ? std::min(cameraBoundsBlendTimer_ /
+                                     cameraBoundsBlendDuration_,
+                                 1.0f)
+                      : 1.0f;
+  const auto lerp = [t](float from, float to) {
+    return from + (to - from) * t;
+  };
+
+  currentCameraBounds_ = frostbite2D::Rect(
+      lerp(cameraBoundsBlendStart_.left(), cameraBoundsBlendTarget_.left()),
+      lerp(cameraBoundsBlendStart_.top(), cameraBoundsBlendTarget_.top()),
+      lerp(cameraBoundsBlendStart_.width(), cameraBoundsBlendTarget_.width()),
+      lerp(cameraBoundsBlendStart_.height(), cameraBoundsBlendTarget_.height()));
+  cameraController_.SetWorldBounds(currentCameraBounds_);
+
+  if (t >= 1.0f) {
+    cameraBoundsBlendActive_ = false;
+  }
 }
 
 void WhiteboxScene::updateBattleZones() {
@@ -146,7 +184,7 @@ void WhiteboxScene::updateBattleZones() {
 
     runtime.triggered = true;
     activeBattleZoneIndex_ = static_cast<int>(i);
-    cameraController_.SetWorldBounds(level_.battleZones[i].cameraBounds);
+    beginCameraBoundsBlend(level_.battleZones[i].cameraBounds);
     break;
   }
 }

game/src/scene/whitebox_scene.h

@@ -31,7 +31,9 @@ private:
   std::vector<BattleZoneDebugInfo> buildBattleZoneDebugInfo() const;
   void configureCamera();
   void toggleDebugOverlay();
+  void beginCameraBoundsBlend(const frostbite2D::Rect& targetBounds);
   void clearActiveBattleZone();
+  void updateCameraBoundsBlend(float deltaTime);
   void updateBattleZones();
   void updateCamera(float deltaTime);
 
@@ -39,6 +41,12 @@ private:
   DebugFlags debugFlags_;
   std::vector<BattleZoneRuntime> battleZoneStates_;
   int activeBattleZoneIndex_ = -1;
+  bool cameraBoundsBlendActive_ = false;
+  float cameraBoundsBlendTimer_ = 0.0f;
+  float cameraBoundsBlendDuration_ = 0.35f;
+  frostbite2D::Rect cameraBoundsBlendStart_;
+  frostbite2D::Rect cameraBoundsBlendTarget_;
+  frostbite2D::Rect currentCameraBounds_;
   CameraController cameraController_;
   StageRenderer stageRenderer_;
   DebugOverlay debugOverlay_;