71 lines
1.7 KiB
GLSL
71 lines
1.7 KiB
GLSL
#[compute]
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#version 450
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#VERSION_DEFINES
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layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
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layout(set = 0, binding = 0) uniform sampler2D source_normal;
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layout(r8, set = 1, binding = 0) uniform restrict writeonly image2D dest_roughness;
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layout(push_constant, std430) uniform Params {
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ivec2 screen_size;
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float curve;
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uint pad;
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}
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params;
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#define HALF_PI 1.5707963267948966
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void main() {
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// Pixel being shaded
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ivec2 pos = ivec2(gl_GlobalInvocationID.xy);
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if (any(greaterThan(pos, params.screen_size))) { //too large, do nothing
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return;
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}
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vec3 normal_accum = vec3(0.0);
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float accum = 0.0;
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for (int i = 0; i <= 1; i++) {
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for (int j = 0; j <= 1; j++) {
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normal_accum += normalize(texelFetch(source_normal, pos + ivec2(i, j), 0).xyz * 2.0 - 1.0);
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accum += 1.0;
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}
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}
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normal_accum /= accum;
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float r = length(normal_accum);
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float limit;
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if (r < 1.0) {
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float threshold = 0.4;
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/*
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//Formula from Filament, does not make sense to me.
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float r2 = r * r;
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float kappa = (3.0f * r - r * r2) / (1.0f - r2);
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float variance = 0.25f / kappa;
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limit = sqrt(min(2.0f * variance, threshold * threshold));
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*/
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/*
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//Formula based on probability distribution graph
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float width = acos(max(0.0,r)); // convert to angle (width)
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float roughness = pow(width,1.7)*0.854492; //approximate (crappy) formula to convert to roughness
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limit = min(sqrt(roughness), threshold); //convert to perceptual roughness and apply threshold
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*/
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limit = min(sqrt(pow(acos(max(0.0, r)) / HALF_PI, params.curve)), threshold); //convert to perceptual roughness and apply threshold
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//limit = 0.5;
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} else {
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limit = 0.0;
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}
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imageStore(dest_roughness, pos, vec4(limit));
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}
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