60 lines
2.0 KiB
GLSL
60 lines
2.0 KiB
GLSL
#version 150
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uniform float viewWidth;
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uniform float viewHeight;
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uniform sampler2D colortex0;
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in vec2 texCoord;
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out vec4 fragColor;
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// Tune these to trade quality vs performance:
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// RADIUS 36, STEP 1 → 5476 samples/pixel (original, ~9fps)
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// RADIUS 36, STEP 3 → 676 samples/pixel (~8x faster)
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// RADIUS 36, STEP 4 → 400 samples/pixel (~14x faster)
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// RADIUS 16, STEP 2 → 324 samples/pixel (smaller brush, fast)
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#define RADIUS 36
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#define STEP 3
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vec3 kuwahara_region(vec2 uv, vec2 ts, int x0, int x1, int y0, int y1, out float outVariance) {
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vec3 colorSum = vec3(0.0);
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float lumaSum = 0.0;
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float lumaSqSum = 0.0;
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float count = 0.0;
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for (int i = x0; i <= x1; i += STEP) {
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for (int j = y0; j <= y1; j += STEP) {
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vec3 c = texture(colortex0, uv + vec2(float(i), float(j)) * ts).rgb;
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float luma = dot(c, vec3(0.299, 0.587, 0.114));
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colorSum += c;
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lumaSum += luma;
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lumaSqSum += luma * luma;
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count += 1.0;
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}
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}
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vec3 mean = colorSum / count;
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float meanLuma = lumaSum / count;
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float variance = (lumaSqSum / count) - (meanLuma * meanLuma);
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outVariance = variance * variance; // square for harder selection
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return mean;
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}
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void main() {
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vec2 ts = vec2(1.0 / viewWidth, 1.0 / viewHeight);
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float v_tr, v_tl, v_bl, v_br;
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vec3 mean_tr = kuwahara_region(texCoord, ts, 0, RADIUS, 0, RADIUS, v_tr);
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vec3 mean_tl = kuwahara_region(texCoord, ts, -RADIUS, 0, 0, RADIUS, v_tl);
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vec3 mean_bl = kuwahara_region(texCoord, ts, -RADIUS, 0, -RADIUS, 0, v_bl);
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vec3 mean_br = kuwahara_region(texCoord, ts, 0, RADIUS, -RADIUS, 0, v_br);
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vec3 finalColor = mean_tr;
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float minVar = v_tr;
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if (v_tl < minVar) { minVar = v_tl; finalColor = mean_tl; }
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if (v_bl < minVar) { minVar = v_bl; finalColor = mean_bl; }
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if (v_br < minVar) { minVar = v_br; finalColor = mean_br; }
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fragColor = vec4(finalColor, 1.0);
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}
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