Init commit

assets/shaders/skybox.hlsl

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+// [新增] 相机背景天空盒。
+// CPU 不创建天空盒网格；VS 使用 SV_VertexID 读取内置 36 个顶点。
+
+#pragma pack_matrix(row_major)
+#include "include/pbr_brdf.hlsli"
+
+cbuffer CBScene : register(b0) {
+    row_major float4x4 gView;
+    row_major float4x4 gProjection;
+    float4 gCameraPosition;
+    float4 gLightDirection;
+    float4 gLightColorIntensity;
+    float4 gAmbientColorIntensity;
+    float4 gRenderParams;            // x=exposure
+};
+
+cbuffer CBIBL : register(b4) {
+    // x=intensity, y=prefilter max mip, z=Y rotation, w=enabled
+    float4 gIblParams;
+};
+
+TextureCube<float4> gSkyboxCube : register(t12);
+SamplerState gSkyboxSampler : register(s4);
+
+static const float3 gCubeVertices[36] = {
+    // -Z
+    float3(-1.0f, -1.0f, -1.0f), float3(-1.0f,  1.0f, -1.0f), float3( 1.0f,  1.0f, -1.0f),
+    float3(-1.0f, -1.0f, -1.0f), float3( 1.0f,  1.0f, -1.0f), float3( 1.0f, -1.0f, -1.0f),
+    // +Z
+    float3(-1.0f, -1.0f,  1.0f), float3( 1.0f,  1.0f,  1.0f), float3(-1.0f,  1.0f,  1.0f),
+    float3(-1.0f, -1.0f,  1.0f), float3( 1.0f, -1.0f,  1.0f), float3( 1.0f,  1.0f,  1.0f),
+    // -X
+    float3(-1.0f, -1.0f, -1.0f), float3(-1.0f, -1.0f,  1.0f), float3(-1.0f,  1.0f,  1.0f),
+    float3(-1.0f, -1.0f, -1.0f), float3(-1.0f,  1.0f,  1.0f), float3(-1.0f,  1.0f, -1.0f),
+    // +X
+    float3( 1.0f, -1.0f, -1.0f), float3( 1.0f,  1.0f,  1.0f), float3( 1.0f, -1.0f,  1.0f),
+    float3( 1.0f, -1.0f, -1.0f), float3( 1.0f,  1.0f, -1.0f), float3( 1.0f,  1.0f,  1.0f),
+    // -Y
+    float3(-1.0f, -1.0f, -1.0f), float3( 1.0f, -1.0f,  1.0f), float3(-1.0f, -1.0f,  1.0f),
+    float3(-1.0f, -1.0f, -1.0f), float3( 1.0f, -1.0f, -1.0f), float3( 1.0f, -1.0f,  1.0f),
+    // +Y
+    float3(-1.0f,  1.0f, -1.0f), float3(-1.0f,  1.0f,  1.0f), float3( 1.0f,  1.0f,  1.0f),
+    float3(-1.0f,  1.0f, -1.0f), float3( 1.0f,  1.0f,  1.0f), float3( 1.0f,  1.0f, -1.0f)
+};
+
+struct VSOutput {
+    float4 positionCS : SV_POSITION;
+    float3 directionWS : TEXCOORD0;
+};
+
+VSOutput VSMain(uint vertexId : SV_VertexID) {
+    VSOutput output;
+
+    const float3 positionWS = gCubeVertices[vertexId];
+
+    // [修改] w=0 只应用相机旋转，不应用相机平移；天空盒因此始终以相机为中心。
+    const float3 positionVS = mul(float4(positionWS, 0.0f), gView).xyz;
+    float4 positionCS = mul(float4(positionVS, 1.0f), gProjection);
+
+    // [新增] 固定到远平面；配合 LESS_EQUAL 和深度不写入，仅覆盖背景像素。
+    positionCS.z = positionCS.w;
+
+    output.positionCS = positionCS;
+    output.directionWS = positionWS;
+    return output;
+}
+
+float3 RotateAroundY(float3 direction, float radians) {
+    float sineValue;
+    float cosineValue;
+    sincos(radians, sineValue, cosineValue);
+
+    return float3(
+        cosineValue * direction.x + sineValue * direction.z,
+        direction.y,
+        -sineValue * direction.x + cosineValue * direction.z);
+}
+
+float4 PSMain(VSOutput input) : SV_TARGET {
+    const float3 sampleDirection = RotateAroundY(
+        normalize(input.directionWS), gIblParams.z);
+
+    float3 color = gSkyboxCube.SampleLevel(
+        gSkyboxSampler, sampleDirection, 0.0f).rgb;
+    // [修改] enabled 只控制物体 IBL；天空背景在 Cube 已加载时始终显示。
+    color *= max(gIblParams.x, 0.0f);
+
+    // 与 PBR 物体使用相同曝光、色调映射和显示编码。
+    color *= max(gRenderParams.x, 0.0f);
+    color = ToneMapACES(color);
+    color = pow(max(color, 0.0f), 1.0f / 2.2f);
+    return float4(color, 1.0f);
+}