Pass
{
    Name "ShadowCaster"
    Tags { "LightMode"="ShadowCaster" }
    ZWrite On
    ZTest LEqual
    ColorMask 0
    Cull Back

    HLSLPROGRAM
    #pragma target 2.0
    #pragma vertex MyShadowVert
    #pragma fragment MyShadowFrag
    #pragma shader_feature_local _ALPHATEST_ON
    #pragma multi_compile_instancing
    // 方向光与点/聚光的法线偏移公式不同，URP 用这个关键字区分
    #pragma multi_compile_vertex _ _CASTING_PUNCTUAL_LIGHT_SHADOW
    #include "Assets/Cookbook/Ch11/MyPBR_DepthPasses.hlsl"
    ENDHLSL
}

// URP 在渲染阴影图时设置这两个变量：方向光用 _LightDirection，点/聚光用 _LightPosition
float3 _LightDirection;
float3 _LightPosition;

DepthVaryings MyShadowVert(DepthAttributes input)
{
    DepthVaryings o = (DepthVaryings)0;
    UNITY_SETUP_INSTANCE_ID(input);
    UNITY_TRANSFER_INSTANCE_ID(input, o);

    float3 positionWS = TransformObjectToWorld(input.positionOS.xyz);
    float3 normalWS   = TransformObjectToWorldNormal(input.normalOS);
#if defined(_CASTING_PUNCTUAL_LIGHT_SHADOW)
    float3 lightDirWS = normalize(_LightPosition - positionWS);
#else
    float3 lightDirWS = _LightDirection;
#endif
    // 深度偏移 + 法线偏移（数值来自灯光的 Bias 设置），对抗 Shadow Acne
    float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, lightDirWS));
    // 把被近裁剪面切掉的投射体压到近平面上（Shadow Pancaking），否则阴影会出洞
#if UNITY_REVERSED_Z
    positionCS.z = min(positionCS.z, UNITY_NEAR_CLIP_VALUE);
#else
    positionCS.z = max(positionCS.z, UNITY_NEAR_CLIP_VALUE);
#endif
    o.positionCS = positionCS;
    o.uv = TRANSFORM_TEX(input.texcoord, _BaseMap);
    return o;
}

half4 MyShadowFrag(DepthVaryings i) : SV_Target
{
    UNITY_SETUP_INSTANCE_ID(i);
    MyAlphaClip(i.uv);
    return 0;
}

Pass
{
    Name "DepthOnly"
    Tags { "LightMode"="DepthOnly" }
    ZWrite On
    ColorMask R
    Cull Back

    HLSLPROGRAM
    #pragma target 2.0
    #pragma vertex MyDepthVert
    #pragma fragment MyDepthFrag
    #pragma shader_feature_local _ALPHATEST_ON
    #pragma multi_compile_instancing
    #include "Assets/Cookbook/Ch11/MyPBR_DepthPasses.hlsl"
    ENDHLSL
}

Pass
{
    Name "DepthNormals"
    Tags { "LightMode"="DepthNormals" }
    ZWrite On
    Cull Back

    HLSLPROGRAM
    #pragma target 2.0
    #pragma vertex MyDepthNormalsVert
    #pragma fragment MyDepthNormalsFrag
    #pragma shader_feature_local _NORMALMAP
    #pragma shader_feature_local _ALPHATEST_ON
    #pragma multi_compile_instancing
    #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/RenderingLayers.hlsl"
    #include "Assets/Cookbook/Ch11/MyPBR_DepthPasses.hlsl"
    ENDHLSL
}

DepthVaryings MyDepthNormalsVert(DepthAttributes input)
{
    DepthVaryings o = (DepthVaryings)0;
    UNITY_SETUP_INSTANCE_ID(input);
    UNITY_TRANSFER_INSTANCE_ID(input, o);
    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
    o.positionCS = TransformObjectToHClip(input.positionOS.xyz);
    o.uv = TRANSFORM_TEX(input.texcoord, _BaseMap);
    VertexNormalInputs nrm = GetVertexNormalInputs(input.normalOS, input.tangentOS);
    o.normalWS = nrm.normalWS;
#if defined(_NORMALMAP)
    o.tangentWS = half4(nrm.tangentWS, input.tangentOS.w * GetOddNegativeScale());
#endif
    return o;
}

void MyDepthNormalsFrag(DepthVaryings i
    , out half4 outNormalWS : SV_Target0
#if defined(_WRITE_RENDERING_LAYERS)
    , out float4 outRenderingLayers : SV_Target1
#endif
    )
{
    UNITY_SETUP_INSTANCE_ID(i);
    UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(i);
    MyAlphaClip(i.uv);
#if defined(_NORMALMAP)
    // SSAO、贴花等读 _CameraNormalsTexture，带上法线贴图细节它们才对得上
    half3 normalTS = UnpackNormalScale(SAMPLE_TEXTURE2D(_BumpMap, sampler_BumpMap, i.uv), _BumpScale);
    float3 bitangent = i.tangentWS.w * cross(i.normalWS, i.tangentWS.xyz);
    float3 normalWS = TransformTangentToWorld(normalTS, half3x3(i.tangentWS.xyz, bitangent, i.normalWS));
#else
    float3 normalWS = i.normalWS;
#endif
    outNormalWS = half4(NormalizeNormalPerPixel(normalWS), 0.0);   // URP 14 存未编码的世界法线
#if defined(_WRITE_RENDERING_LAYERS)
    outRenderingLayers = float4(EncodeMeshRenderingLayer(GetMeshRenderingLayer()), 0, 0, 0);
#endif
}

Pass
{
    Name "Meta"
    Tags { "LightMode"="Meta" }
    Cull Off

    HLSLPROGRAM
    #pragma target 2.0
    #pragma vertex MyMetaVert
    #pragma fragment MyMetaFrag
    #pragma shader_feature_local_fragment _MASKMAP
    #pragma shader_feature_local_fragment _EMISSION
    #pragma shader_feature_local_fragment _ALPHATEST_ON
    #pragma shader_feature EDITOR_VISUALIZATION
    #include "Assets/Cookbook/Ch11/MyPBR_MetaPass.hlsl"
    ENDHLSL
}

MetaVaryings MyMetaVert(MetaAttributes input)
{
    MetaVaryings o = (MetaVaryings)0;
    // 烘焙时 unity_MetaVertexControl 指示用哪套 UV 当“屏幕位置”
    o.positionCS = UnityMetaVertexPosition(input.positionOS.xyz, input.uv1, input.uv2);
    o.uv = TRANSFORM_TEX(input.uv0, _BaseMap);
#if defined(EDITOR_VISUALIZATION)
    UnityEditorVizData(input.positionOS.xyz, input.uv0, input.uv1, input.uv2, o.VizUV, o.LightCoord);
#endif
    return o;
}

half4 MyMetaFrag(MetaVaryings i) : SV_Target
{
    MySurface s = MySampleSurface(i.uv);
    MyMaterial m = MyInitMaterial(s.albedo, s.metallic, s.perceptualRoughness);

    UnityMetaInput meta = (UnityMetaInput)0;
    // 反弹光的颜色：漫反射色为主；粗糙金属的镜面反射在烘焙器看来也像“漫反射”，
    // 按粗糙度加一部分 F0 进去（与 URP Lit 的经验做法相同）
    meta.Albedo = m.diffuseColor + m.f0 * (m.perceptualRoughness * m.perceptualRoughness) * 0.5;
    meta.Emission = s.emission;
#if defined(EDITOR_VISUALIZATION)
    meta.VizUV = i.VizUV;
    meta.LightCoord = i.LightCoord;
#endif
    return UnityMetaFragment(meta);
}