使用Unity Shader的阴影计算宏时需要注意的东西

Posted 2020-12-10 winsons

根据TRANSFER_SHADOW的宏定义，a2v结构体中的顶点坐标变量名必须是vertex，顶点着色器的输入结构体a2v必须命名为v，且v2f中的顶点位置变量必须命名为pos。

#if defined (SHADOWS_SCREEN)

    #if defined(UNITY_NO_SCREENSPACE_SHADOWS)
        UNITY_DECLARE_SHADOWMAP(_ShadowMapTexture);
        #define TRANSFER_SHADOW(a) a._ShadowCoord = mul( unity_WorldToShadow[0], mul( unity_ObjectToWorld, v.vertex ) );
        inline fixed unitySampleShadow (unityShadowCoord4 shadowCoord)
        {
            #if defined(SHADOWS_NATIVE)
                fixed shadow = UNITY_SAMPLE_SHADOW(_ShadowMapTexture, shadowCoord.xyz);
                shadow = _LightShadowData.r + shadow * (1-_LightShadowData.r);
                return shadow;
            #else
                unityShadowCoord dist = SAMPLE_DEPTH_TEXTURE(_ShadowMapTexture, shadowCoord.xy);
                // tegra is confused if we use?_LightShadowData.x directly
                // with "ambiguous overloaded function reference max(mediump float, float)"
                unityShadowCoord lightShadowDataX = _LightShadowData.x;
                unityShadowCoord threshold = shadowCoord.z;
                return max(dist > threshold, lightShadowDataX);
            #endif
        }

    #else // UNITY_NO_SCREENSPACE_SHADOWS
        UNITY_DECLARE_SCREENSPACE_SHADOWMAP(_ShadowMapTexture);
        #define TRANSFER_SHADOW(a) a._ShadowCoord = ComputeScreenPos(a.pos);
        inline fixed unitySampleShadow (unityShadowCoord4 shadowCoord)
        {
            fixed shadow = UNITY_SAMPLE_SCREEN_SHADOW(_ShadowMapTexture, shadowCoord);
            return shadow;
        }

    #endif

    #define SHADOW_COORDS(idx1) unityShadowCoord4 _ShadowCoord : TEXCOORD##idx1;
    #define SHADOW_ATTENUATION(a) unitySampleShadow(a._ShadowCoord)
#endif