60 lines
1.6 KiB
GLSL
60 lines
1.6 KiB
GLSL
// VERTEX_SHADER:
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// blur.glsl
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uniform float u_blur_radius;
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uniform vec2 u_blur_size;
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uniform vec2 u_blur_dir;
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_OUT_ vec2 pixel_step;
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_OUT_ float pixels_per_side;
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_OUT_ vec3 initial_gaussian;
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const float PI = 3.14159265;
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const float RADIUS_MULTIPLIER = 2.0;
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void main() {
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gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
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vUv = vec2(aUv.x, aUv.y);
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pixel_step = (vec2(1.0) / u_blur_size) * u_blur_dir;
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pixels_per_side = floor(u_blur_radius * RADIUS_MULTIPLIER / 2.0);
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float sigma = u_blur_radius / 2.0; // *shrug*
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initial_gaussian.x = 1.0 / (sqrt(2.0 * PI) * sigma);
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initial_gaussian.y = exp(-0.5 / (sigma * sigma));
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initial_gaussian.z = initial_gaussian.y * initial_gaussian.y;
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}
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// FRAGMENT_SHADER:
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// blur.glsl
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_IN_ vec2 pixel_step;
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_IN_ float pixels_per_side;
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_IN_ vec3 initial_gaussian;
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// blur_radius 0 is NOT supported and MUST be caught before.
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// Partially from http://callumhay.blogspot.com/2010/09/gaussian-blur-shader-glsl.html
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void main() {
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vec3 incrementalGaussian = initial_gaussian;
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float coefficientSum = 0.0;
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vec4 sum = GskTexture(u_source, vUv) * incrementalGaussian.x;
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coefficientSum += incrementalGaussian.x;
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incrementalGaussian.xy *= incrementalGaussian.yz;
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vec2 p = pixel_step;
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for (int i = 1; i <= int(pixels_per_side); i++) {
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sum += GskTexture(u_source, vUv - p) * incrementalGaussian.x;
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sum += GskTexture(u_source, vUv + p) * incrementalGaussian.x;
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coefficientSum += 2.0 * incrementalGaussian.x;
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incrementalGaussian.xy *= incrementalGaussian.yz;
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p += pixel_step;
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}
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gskSetOutputColor(sum / coefficientSum);
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}
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