47 lines
1.1 KiB
GLSL
47 lines
1.1 KiB
GLSL
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out vec4 FragColor;
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void main() {
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vec3 N, T, B, V;
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float NV = ( 1.0 - (clamp(gl_FragCoord.y / BRDF_LUT_SIZE, 1e-4, 0.9999)));
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float sqrtRoughness = clamp(gl_FragCoord.x / BRDF_LUT_SIZE, 1e-4, 0.9999);
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float a = sqrtRoughness * sqrtRoughness;
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float a2 = a * a;
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N = vec3(0.0, 0.0, 1.0);
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T = vec3(1.0, 0.0, 0.0);
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B = vec3(0.0, 1.0, 0.0);
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V = vec3(sqrt(1.0 - NV * NV), 0.0, NV);
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setup_noise();
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/* Integrating BRDF */
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float brdf_accum = 0.0;
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float fresnel_accum = 0.0;
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for (float i = 0; i < sampleCount; i++) {
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vec3 H = sample_ggx(i, a2, N, T, B); /* Microfacet normal */
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vec3 L = -reflect(V, H);
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float NL = L.z;
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if (NL > 0.0) {
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float NH = max(H.z, 0.0);
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float VH = max(dot(V, H), 0.0);
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float G1_v = G1_Smith_GGX(NV, a2);
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float G1_l = G1_Smith_GGX(NL, a2);
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float G_smith = 4.0 * NV * NL / (G1_v * G1_l); /* See G1_Smith_GGX for explanations. */
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float brdf = (G_smith * VH) / (NH * NV);
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float Fc = pow(1.0 - VH, 5.0);
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brdf_accum += (1.0 - Fc) * brdf;
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fresnel_accum += Fc * brdf;
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}
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}
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brdf_accum /= sampleCount;
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fresnel_accum /= sampleCount;
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FragColor = vec4(brdf_accum, fresnel_accum, 0.0, 1.0);
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}
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