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uniform sampler1D texHammersley;
uniform sampler2D texJitter;
uniform float sampleCount;
uniform float invSampleCount;
vec2 jitternoise = vec2(0.0);
void setup_noise(void)
{
jitternoise = texture(texJitter, gl_FragCoord.xy / NOISE_SIZE).rg; /* Global variable */
}
vec3 hammersley_3d(float i, float invsamplenbr)
{
vec3 Xi; /* Theta, cos(Phi), sin(Phi) */
Xi.x = i * invsamplenbr; /* i/samples */
Xi.x = fract(Xi.x + jitternoise.x);
int u = int(mod(i + jitternoise.y * HAMMERSLEY_SIZE, HAMMERSLEY_SIZE));
Xi.yz = texelFetch(texHammersley, u, 0).rg;
return Xi;
}
vec3 hammersley_3d(float i)
{
return hammersley_3d(i, invSampleCount);
}
/* -------------- BSDFS -------------- */
float pdf_ggx_reflect(float NH, float a2)
{
return NH * a2 / D_ggx_opti(NH, a2);
}
vec3 sample_ggx(float nsample, float a2, vec3 N, vec3 T, vec3 B)
{
vec3 Xi = hammersley_3d(nsample);
/* Theta is the aperture angle of the cone */
float z = sqrt( (1.0 - Xi.x) / ( 1.0 + a2 * Xi.x - Xi.x ) ); /* cos theta */
float r = sqrt( 1.0 - z * z ); /* sin theta */
float x = r * Xi.y;
float y = r * Xi.z;
/* Microfacet Normal */
vec3 Ht = vec3(x, y, z);
return tangent_to_world(Ht, N, T, B);
}
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