Clément Foucault
83ac8628c4
This modifies the principled BSDF and the Glass BSDF which now have better fit to multiscatter GGX. Code to generate the LUT have been updated and can run at runtime. The refraction LUT has been changed to have the critical angle always centered around one pixel so that interpolation can be mitigated. Offline LUT data will be updated in another commit This simplify the BTDF retreival removing the manual clean cut at low roughness. This maximize the precision of the LUT by scalling the sides by the critical angle. I also touched the ior > 1.0 approximation to be smoother. Also incluse some cleanup of bsdf_sampling.glsl
90 lines
2.1 KiB
GLSL
90 lines
2.1 KiB
GLSL
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#pragma BLENDER_REQUIRE(bsdf_common_lib.glsl)
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uniform sampler1D texHammersley;
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vec3 tangent_to_world(vec3 vector, vec3 N, vec3 T, vec3 B)
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{
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return T * vector.x + B * vector.y + N * vector.z;
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}
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#ifdef HAMMERSLEY_SIZE
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vec3 hammersley_3d(float i, float invsamplenbr)
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{
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vec3 Xi; /* Theta, cos(Phi), sin(Phi) */
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Xi.x = i * invsamplenbr;
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Xi.yz = texelFetch(texHammersley, int(i), 0).rg;
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return Xi;
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}
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#endif
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/* -------------- BSDFS -------------- */
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float pdf_ggx_reflect(float NH, float a2)
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{
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return NH * a2 / D_ggx_opti(NH, a2);
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}
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float pdf_hemisphere()
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{
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return 0.5 * M_1_PI;
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}
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vec3 sample_ggx(vec3 rand, float a2)
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{
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/* Theta is the aperture angle of the cone */
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float z = sqrt((1.0 - rand.x) / (1.0 + a2 * rand.x - rand.x)); /* cos theta */
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float r = sqrt(max(0.0, 1.0f - z * z)); /* sin theta */
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float x = r * rand.y;
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float y = r * rand.z;
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/* Microfacet Normal */
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return vec3(x, y, z);
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}
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vec3 sample_ggx(vec3 rand, float a2, vec3 N, vec3 T, vec3 B, out float NH)
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{
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vec3 Ht = sample_ggx(rand, a2);
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NH = Ht.z;
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return tangent_to_world(Ht, N, T, B);
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}
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#ifdef HAMMERSLEY_SIZE
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vec3 sample_ggx(float nsample, float inv_sample_count, float a2, vec3 N, vec3 T, vec3 B)
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{
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vec3 Xi = hammersley_3d(nsample, inv_sample_count);
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vec3 Ht = sample_ggx(Xi, a2);
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return tangent_to_world(Ht, N, T, B);
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}
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vec3 sample_hemisphere(float nsample, float inv_sample_count, vec3 N, vec3 T, vec3 B)
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{
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vec3 Xi = hammersley_3d(nsample, inv_sample_count);
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float z = Xi.x; /* cos theta */
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float r = sqrt(max(0.0, 1.0f - z * z)); /* sin theta */
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float x = r * Xi.y;
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float y = r * Xi.z;
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vec3 Ht = vec3(x, y, z);
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return tangent_to_world(Ht, N, T, B);
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}
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vec3 sample_cone(float nsample, float inv_sample_count, float angle, vec3 N, vec3 T, vec3 B)
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{
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vec3 Xi = hammersley_3d(nsample, inv_sample_count);
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float z = cos(angle * Xi.x); /* cos theta */
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float r = sqrt(max(0.0, 1.0f - z * z)); /* sin theta */
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float x = r * Xi.y;
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float y = r * Xi.z;
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vec3 Ht = vec3(x, y, z);
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return tangent_to_world(Ht, N, T, B);
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}
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#endif
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