fix: tonemap 输出预乘 alpha 匹配 PRE_MULTIPLIED 合成模式 + 调整地面位置

App/main.cpp

@@ -47,14 +47,14 @@ protected:
         EnableImGui();
 
         // 模型资产（AssetManager 负责加载/缓存/生命周期，返回句柄）
-        auto backpack = GetAssets().LoadModel("assets/models/backpack/backpack.obj");
+        const auto backpack = GetAssets().LoadModel("assets/models/backpack/backpack.obj");
 
         // 地面：程序化纯色平面（半边长 15，中心 y=-2）
-        auto ground = GetAssets().CreatePlane(15.0f, 140, 140, 145);
+        const auto ground = GetAssets().CreatePlane(15.0f, 140, 140, 145);
 
         m_Ground = scene.CreateEntity("Ground");
         m_Ground.AddComponent<TransformComponent>()
-                .SetPosition(glm::vec3(0.0f, -4.5f, 0.0f))
+                .SetPosition(glm::vec3(0.0f, -0.5f, 0.0f))
                 .Compose();
         m_Ground.AddComponent<MeshRendererComponent>(MeshRendererComponent{ground});
 

shaders/tonemap.frag

@@ -35,5 +35,5 @@ void main() {
         ? acesFilm(hdr)
         : clamp(hdr, 0.0, 1.0);
 
-    outColor = vec4(pow(mapped, vec3(1.0 / 2.2)), alpha);
+    outColor = vec4(pow(mapped, vec3(1.0 / 2.2)) * alpha, alpha);
 }