51 lines
No EOL
1.4 KiB
GLSL
51 lines
No EOL
1.4 KiB
GLSL
#include "../sampler.glsl"
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#include "../math/saturate.glsl"
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#include "../math/sum.glsl"
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/*
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contributors: nan
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description: |
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morphological erosion operation. Based on:
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https://lettier.github.io/3d-game-shaders-for-beginners/dilation.html
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https://www.shadertoy.com/view/WsyXWc
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use: erode(<SAMPLER_TYPE> texture, <float2> st, <float2> pixels_scale, <int> passes)
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options:
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- SAMPLER_FNC(TEX, UV): optional depending the target version of GLSL (texture2D(...) or texture(...))
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- EROSION_TYPE
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- EROSION_SAMPLE_FNC(TEX, UV)
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*/
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#ifndef EROSION_TYPE
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#define EROSION_TYPE float
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#endif
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#ifndef EROSION_SAMPLE_FNC
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#define EROSION_SAMPLE_FNC(TEX, UV) SAMPLER_FNC(TEX, UV).x
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#endif
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#ifndef FNC_EROSION
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#define FNC_EROSION
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EROSION_TYPE erosion(SAMPLER_TYPE tex, vec2 st, vec2 pixel, int radius) {
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float invKR = 1.0 / float(radius);
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EROSION_TYPE acc = EROSION_TYPE(1.0);
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float w = 0.0;
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for(int i = -radius; i <= radius; ++i)
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for(int j = -radius; j <= radius; ++j) {
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vec2 rxy = vec2(ivec2(i, j));
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vec2 kst = rxy * invKR;
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vec2 texOffset = st + rxy * pixel;
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float kernel = saturate(1.0 - dot(kst, kst));
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EROSION_TYPE t = EROSION_SAMPLE_FNC(tex, texOffset);
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EROSION_TYPE v = t - kernel;
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if (sum(v) < sum(acc)) {
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acc = v;
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w = kernel;
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}
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}
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return acc + w;
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}
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#endif |