gaussian 阴影

最新推荐文章于 2025-09-10 00:52:10 发布

原创最新推荐文章于 2025-09-10 00:52:10 发布 · 158 阅读

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该代码片段展示了两种不同的阴影投射方法。一种是基于高斯模糊的阴影计算，另一种是使用偏移采样进行阴影映射。在高斯方法中，对纹理进行多次采样并累加以模拟模糊效果。在阴影映射方法中，通过偏移坐标并在多个样本上应用纹理投影来计算阴影。这两种方法都涉及到纹理采样、浮点运算以及对阴影贴图的访问。

float my_sample( sampler2DShadow TEXTURE, vec4 sc )
{
#if 1
    //gaussian
    float shadow = 0.0;                                                                                                     
    for(int i = -2; i <= 2; ++i)                                                                                             
    {                                                                                                                         
        for(int j = -2; j <= 2; ++j)                                                                                          
        {                                                                                                                 
            shadow += textureProjOffset(TEXTURE, sc, ivec2(i, j)) * 0.04;                    
        }                                                                                                                 
    }                                                                                                                       
                                                                                                                           
    return shadow;                                                                     
#else
   //return 1;
    ivec3 offsetCoord;
    offsetCoord.xy = ivec2( mod( gl_FragCoord.xy, OffsetTexSize.xy ) );

    float sum = 0.0, shadow = 1.0;
    int samplesDiv2 = int(OffsetTexSize.z);
    
    float R = Radius * 1;

    // Don't test points behind the light source.
    if( sc.z >= 0 )
    {
        for( int i = 0 ; i < 4; i++ ) {
            offsetCoord.z = i;
            vec4 offsets = texelFetch(u_shadow_map_Jittering,offsetCoord,0) * R * sc.w;

            sc.xy = sc.xy + offsets.xy;
            sum += textureProj(TEXTURE, sc);
            sc.xy = sc.xy + offsets.zw;
            sum += textureProj(TEXTURE, sc);
        }
        shadow = sum / 8.0;

        if( shadow != 1.0 && shadow != 0.0 ) {
            for( int i = 4; i < samplesDiv2; i++ ) {
                offsetCoord.z = i;
                vec4 offsets = texelFetch(u_shadow_map_Jittering, offsetCoord,0) * R * sc.w;

                sc.xy = sc.xy + offsets.xy;
                sum += textureProj(TEXTURE, sc);
                sc.xy = sc.xy + offsets.zw;
                sum += textureProj(TEXTURE, sc);
            }
            shadow = sum / float(samplesDiv2 * 2.0);
        }
    }
    
    return shadow;
#endif
}