144 lines
4.9 KiB
GLSL
Executable file
144 lines
4.9 KiB
GLSL
Executable file
const float PI = 3.14159265359;
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const vec2 PoissonOffsets[64] = {
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vec2(0.0617981, 0.07294159),
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vec2(0.6470215, 0.7474022),
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vec2(-0.5987766, -0.7512833),
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vec2(-0.693034, 0.6913887),
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vec2(0.6987045, -0.6843052),
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vec2(-0.9402866, 0.04474335),
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vec2(0.8934509, 0.07369385),
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vec2(0.1592735, -0.9686295),
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vec2(-0.05664673, 0.995282),
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vec2(-0.1203411, -0.1301079),
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vec2(0.1741608, -0.1682285),
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vec2(-0.09369049, 0.3196758),
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vec2(0.185363, 0.3213367),
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vec2(-0.1493771, -0.3147511),
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vec2(0.4452095, 0.2580113),
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vec2(-0.1080467, -0.5329178),
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vec2(0.1604507, 0.5460774),
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vec2(-0.4037193, -0.2611179),
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vec2(0.5947998, -0.2146744),
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vec2(0.3276062, 0.9244621),
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vec2(-0.6518704, -0.2503952),
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vec2(-0.3580975, 0.2806469),
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vec2(0.8587891, 0.4838005),
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vec2(-0.1596546, -0.8791054),
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vec2(-0.3096867, 0.5588146),
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vec2(-0.5128918, 0.1448544),
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vec2(0.8581337, -0.424046),
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vec2(0.1562584, -0.5610626),
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vec2(-0.7647934, 0.2709858),
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vec2(-0.3090832, 0.9020988),
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vec2(0.3935608, 0.4609676),
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vec2(0.3929337, -0.5010948),
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vec2(-0.8682281, -0.1990303),
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vec2(-0.01973724, 0.6478714),
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vec2(-0.3897587, -0.4665619),
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vec2(-0.7416366, -0.4377831),
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vec2(-0.5523247, 0.4272514),
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vec2(-0.5325066, 0.8410385),
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vec2(0.3085465, -0.7842533),
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vec2(0.8400612, -0.200119),
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vec2(0.6632416, 0.3067062),
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vec2(-0.4462856, -0.04265022),
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vec2(0.06892014, 0.812484),
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vec2(0.5149567, -0.7502338),
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vec2(0.6464897, -0.4666451),
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vec2(-0.159861, 0.1038342),
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vec2(0.6455986, 0.04419327),
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vec2(-0.7445076, 0.5035095),
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vec2(0.9430245, 0.3139912),
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vec2(0.0349884, -0.7968109),
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vec2(-0.9517487, 0.2963554),
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vec2(-0.7304786, -0.01006928),
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vec2(-0.5862702, -0.5531025),
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vec2(0.3029106, 0.09497032),
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vec2(0.09025345, -0.3503742),
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vec2(0.4356628, -0.0710125),
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vec2(0.4112572, 0.7500054),
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vec2(0.3401214, -0.3047142),
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vec2(-0.2192158, -0.6911137),
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vec2(-0.4676369, 0.6570358),
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vec2(0.6295372, 0.5629555),
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vec2(0.1253822, 0.9892166),
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vec2(-0.1154335, 0.8248222),
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vec2(-0.4230408, -0.7129914)
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};
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// GGX/Trowbridge-Reitz Normal Distribution
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float ggx_distribution(const vec3 N, const vec3 H, const float roughness) {
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const float roughness_squared = roughness * roughness;
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const float NdotH = dot(N, H);
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const float denominator = (NdotH * NdotH) * (roughness_squared - 1.0) + 1.0;
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return roughness_squared / (PI * (denominator * denominator));
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}
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// Slick Geometry
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float geometry_slick_direct(const vec3 N, const vec3 V, const float roughness) {
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const float NdotV = clamp(dot(N, V), 0.0, 1.0);
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const float denominator = NdotV * (1.0 - roughness) + roughness;
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return NdotV / denominator;
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}
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// GGX Smith Geometry, using GGX slick but combining both the view direction and the light direction
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float geometry_smith(const vec3 N, const vec3 V, const vec3 L, float roughness) {
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const float dotNV = max(dot(N, V), 0.0);
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const float dotNL = max(dot(N, L), 0.0);
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const float k = (roughness * roughness) / 2.0;
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const float GL = dotNL / (dotNL * (1.0 - k) + k);
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const float GV = dotNV / (dotNV * (1.0 - k) + k);
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return GL * GV;
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}
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// Fresnel Shlick
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vec3 fresnel_schlick(const float cos_theta, const vec3 F0) {
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return F0 + (1.0 - F0) * pow(1.0 - cos_theta, 5.0);
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}
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vec3 fresnel_schlick_roughness(float cosTheta, vec3 F0, float roughness) {
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return F0 + (max(vec3(1.0 - roughness), F0) - F0) * pow(1.0 - cosTheta, 5.0);
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}
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// efficient VanDerCorpus calculation from http://holger.dammertz.org/stuff/notes_HammersleyOnHemisphere.html
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float radical_inverse(uint bits) {
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bits = (bits << 16u) | (bits >> 16u);
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bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
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bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
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bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
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bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
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return float(bits) * 2.3283064365386963e-10;
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}
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vec2 hammersley(const uint i, const uint N) {
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return vec2(float(i) / float(N), radical_inverse(i));
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}
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vec3 importance_sample_ggx(const vec2 Xi, const vec3 N, const float roughness) {
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const float a = roughness*roughness;
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const float phi = 2.0 * PI * Xi.x;
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const float cosTheta = sqrt((1.0 - Xi.y) / (1.0 + (a*a - 1.0) * Xi.y));
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const float sinTheta = sqrt(1.0 - cosTheta*cosTheta);
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// from spherical coordinates to cartesian coordinates - halfway vector
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vec3 H;
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H.x = cos(phi) * sinTheta;
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H.y = sin(phi) * sinTheta;
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H.z = cosTheta;
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// from tangent-space H vector to world-space sample vector
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const vec3 up = abs(N.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
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const vec3 tangent = normalize(cross(up, N));
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const vec3 bitangent = cross(N, tangent);
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return normalize(tangent * H.x + bitangent * H.y + N * H.z);
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}
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