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#pragma BLENDER_REQUIRE(bsdf_common_lib.glsl)
uniform sampler1D texHammersley;
vec3 tangent_to_world(vec3 vector, vec3 N, vec3 T, vec3 B)
{
return T * vector.x + B * vector.y + N * vector.z;
}
#ifdef HAMMERSLEY_SIZE
vec3 hammersley_3d(float i, float invsamplenbr)
{
vec3 Xi; /* Theta, cos(Phi), sin(Phi) */
Xi.x = i * invsamplenbr;
Xi.yz = texelFetch(texHammersley, int(i), 0).rg;
return Xi;
}
#endif
/* -------------- BSDFS -------------- */
float pdf_ggx_reflect(float NH, float a2)
{
return NH * a2 / D_ggx_opti(NH, a2);
}
float pdf_hemisphere()
{
return 0.5 * M_1_PI;
}
vec3 sample_ggx(vec3 rand, float a2)
{
/* Theta is the cone angle. */
float z = sqrt((1.0 - rand.x) / (1.0 + a2 * rand.x - rand.x)); /* cos theta */
float r = sqrt(max(0.0, 1.0f - z * z)); /* sin theta */
float x = r * rand.y;
float y = r * rand.z;
/* Microfacet Normal */
return vec3(x, y, z);
}
vec3 sample_ggx(vec3 rand, float a2, vec3 N, vec3 T, vec3 B, out float NH)
{
vec3 Ht = sample_ggx(rand, a2);
NH = Ht.z;
return tangent_to_world(Ht, N, T, B);
}
#ifdef HAMMERSLEY_SIZE
vec3 sample_ggx(float nsample, float inv_sample_count, float a2, vec3 N, vec3 T, vec3 B)
{
vec3 Xi = hammersley_3d(nsample, inv_sample_count);
vec3 Ht = sample_ggx(Xi, a2);
return tangent_to_world(Ht, N, T, B);
}
vec3 sample_hemisphere(float nsample, float inv_sample_count, vec3 N, vec3 T, vec3 B)
{
vec3 Xi = hammersley_3d(nsample, inv_sample_count);
float z = Xi.x; /* cos theta */
float r = sqrt(max(0.0, 1.0f - z * z)); /* sin theta */
float x = r * Xi.y;
float y = r * Xi.z;
vec3 Ht = vec3(x, y, z);
return tangent_to_world(Ht, N, T, B);
}
vec3 sample_cone(float nsample, float inv_sample_count, float angle, vec3 N, vec3 T, vec3 B)
{
vec3 Xi = hammersley_3d(nsample, inv_sample_count);
float z = cos(angle * Xi.x); /* cos theta */
float r = sqrt(max(0.0, 1.0f - z * z)); /* sin theta */
float x = r * Xi.y;
float y = r * Xi.z;
vec3 Ht = vec3(x, y, z);
return tangent_to_world(Ht, N, T, B);
}
#endif
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