33 lines
1.1 KiB
GLSL
33 lines
1.1 KiB
GLSL
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uniform sampler2D texIES;
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float iesAttenuation(vec3 l) {
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const float PI = 3.1415926535;
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// https://seblagarde.files.wordpress.com/2015/07/course_notes_moving_frostbite_to_pbr_v32.pdf
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// Sample direction into light space
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// vec3 iesSampleDirection = mul(light.worldToLight , -L);
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// Cartesian to spherical
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// Texture encoded with cos( phi ), scale from -1 - >1 to 0 - >1
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// float phiCoord = (iesSampleDirection.z * 0.5f) + 0.5f;
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// float theta = atan2 (iesSampleDirection.y , iesSampleDirection .x);
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// float thetaCoord = theta * (1.0 / (PI * 2.0));
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// float iesProfileScale = texture(texIES, vec2(thetaCoord, phiCoord)).r;
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// return iesProfileScale;
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// 1D texture
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// vec3 pl = normalize(p - lightPos);
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// float f = asin(dot(pl, l)) / PI + 0.5;
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// return texture(texIES, vec2(f, 0.0)).r;
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// 1D texture
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// float cosTheta = dot(lightToPos, lightDir);
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// float angle = acos(cosTheta) * (1.0 / PI);
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// return texture(texIES, vec2(angle, 0.0), 0.0).r;
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// Based on https://github.com/tobspr/RenderPipeline
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float hor = acos(l.z) / PI;
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float vert = atan(l.x, l.y) * (1.0 / (PI * 2.0)) + 0.5;
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return texture(texIES, vec2(hor, vert)).r;
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}
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