Clément Foucault
ba75ea8012
This removes the need for per mipmap scalling factor and trilinear interpolation issues. We pad the texture so that all mipmaps have pixels in the next mip. This simplifies the downsampling shader too. This also change the SSR radiance buffer as well in the same fashion.
72 lines
2.0 KiB
GLSL
72 lines
2.0 KiB
GLSL
/**
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* Shader that down-sample depth buffer,
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* saving min and max value of each texel in the above mipmaps.
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* Adapted from http://rastergrid.com/blog/2010/10/hierarchical-z-map-based-occlusion-culling/
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*
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* Major simplification has been made since we pad the buffer to always be bigger than input to
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* avoid mipmapping misalignement.
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*/
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#ifdef LAYERED
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uniform sampler2DArray depthBuffer;
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uniform int depthLayer;
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#else
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uniform sampler2D depthBuffer;
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#endif
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#ifdef LAYERED
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# define sampleLowerMip(t) texture(depthBuffer, vec3(t, depthLayer)).r
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# define gatherLowerMip(t) textureGather(depthBuffer, vec3(t, depthLayer))
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#else
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# define sampleLowerMip(t) texture(depthBuffer, t).r
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# define gatherLowerMip(t) textureGather(depthBuffer, t)
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#endif
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#ifdef MIN_PASS
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# define minmax2(a, b) min(a, b)
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# define minmax3(a, b, c) min(min(a, b), c)
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# define minmax4(a, b, c, d) min(min(min(a, b), c), d)
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#else /* MAX_PASS */
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# define minmax2(a, b) max(a, b)
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# define minmax3(a, b, c) max(max(a, b), c)
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# define minmax4(a, b, c, d) max(max(max(a, b), c), d)
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#endif
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/* On some AMD card / driver combination, it is needed otherwise,
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* the shader does not write anything. */
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#if defined(GPU_INTEL) || defined(GPU_ATI)
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out vec4 fragColor;
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#endif
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void main()
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{
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vec2 texel = gl_FragCoord.xy;
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vec2 texel_size = 1.0 / vec2(textureSize(depthBuffer, 0).xy);
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#ifdef COPY_DEPTH
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vec2 uv = texel * texel_size;
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float val = sampleLowerMip(uv);
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#else
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vec2 uv = texel * 2.0 * texel_size;
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vec4 samp;
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# ifdef GPU_ARB_texture_gather
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samp = gatherLowerMip(uv);
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# else
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samp.x = sampleLowerMip(uv + vec2(-0.5, -0.5) * texel_size);
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samp.y = sampleLowerMip(uv + vec2(-0.5, 0.5) * texel_size);
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samp.z = sampleLowerMip(uv + vec2(0.5, -0.5) * texel_size);
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samp.w = sampleLowerMip(uv + vec2(0.5, 0.5) * texel_size);
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# endif
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float val = minmax4(samp.x, samp.y, samp.z, samp.w);
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#endif
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#if defined(GPU_INTEL) || defined(GPU_ATI)
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/* Use color format instead of 24bit depth texture */
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fragColor = vec4(val);
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#endif
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gl_FragDepth = val;
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}
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