71 lines
2.0 KiB
Forth
71 lines
2.0 KiB
Forth
|
#version 460 core
|
||
|
|
out vec4 FragColor;
|
||
|
|
in vec3 localPos;
|
||
|
|
|
||
|
|
uniform samplerCube environmentMap;
|
||
|
|
uniform float roughness;
|
||
|
|
|
||
|
|
const float PI = 3.14159265359;
|
||
|
|
|
||
|
|
vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness){
|
||
|
|
float a = roughness*roughness;
|
||
|
|
|
||
|
|
float phi = 2.0 * PI * Xi.x;
|
||
|
|
float cosTheta = sqrt((1.0 - Xi.y) / (1.0 + (a*a - 1.0) * Xi.y));
|
||
|
|
float sinTheta = sqrt(1.0 - cosTheta*cosTheta);
|
||
|
|
|
||
|
|
// Spherical to cartesian
|
||
|
|
vec3 H;
|
||
|
|
H.x = cos(phi) * sinTheta;
|
||
|
|
H.y = sin(phi) * sinTheta;
|
||
|
|
H.z = cosTheta;
|
||
|
|
|
||
|
|
// tangent space to world sample vector
|
||
|
|
vec3 up = abs(N.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
|
||
|
|
vec3 tangent = normalize(cross(up,N));
|
||
|
|
vec3 bitangent = cross(N, tangent);
|
||
|
|
vec3 sampleVec = tangent * H.x + bitangent * H.y + N * H.z;
|
||
|
|
|
||
|
|
return normalize(sampleVec);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// Generate Van Der Corput sequence
|
||
|
|
float RadicalInverse_VdC(uint bits){
|
||
|
|
bits = (bits << 16u) | (bits >> 16u);
|
||
|
|
bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
|
||
|
|
bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
|
||
|
|
bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
|
||
|
|
bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
|
||
|
|
return float(bits) * 2.3283064365386963e-10; // / 0x100000000
|
||
|
|
}
|
||
|
|
|
||
|
|
vec2 Hammersley(uint i, uint N){
|
||
|
|
return vec2(float(i)/float(N), RadicalInverse_VdC(i));
|
||
|
|
}
|
||
|
|
|
||
|
|
void main(){
|
||
|
|
vec3 N = normalize(localPos);
|
||
|
|
vec3 R = N;
|
||
|
|
vec3 V = R;
|
||
|
|
|
||
|
|
const uint SAMPLE_COUNT = 1024u;
|
||
|
|
float totalWeight = 0.0;
|
||
|
|
vec3 prefilteredColor = vec3(0.0);
|
||
|
|
for(uint i = 0u; i < SAMPLE_COUNT; ++i)
|
||
|
|
{
|
||
|
|
vec2 Xi = Hammersley(i, SAMPLE_COUNT);
|
||
|
|
vec3 H = ImportanceSampleGGX(Xi, N, roughness);
|
||
|
|
vec3 L = normalize(2.0 * dot(V,H) * H - V );
|
||
|
|
|
||
|
|
float NdotL = max(dot(N, L), 0.0);
|
||
|
|
if(NdotL > 0.0){
|
||
|
|
prefilteredColor += texture(environmentMap, L).rgb * NdotL;
|
||
|
|
totalWeight += NdotL;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
prefilteredColor = prefilteredColor / totalWeight;
|
||
|
|
|
||
|
|
FragColor = vec4(prefilteredColor, 1.0);
|
||
|
|
}
|