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#pragma BLENDER_REQUIRE(random_lib.glsl)
#pragma BLENDER_REQUIRE(bsdf_sampling_lib.glsl)
#pragma BLENDER_REQUIRE(common_math_geom_lib.glsl)
#pragma BLENDER_REQUIRE(irradiance_lib.glsl)
uniform samplerCube probeHdr;
uniform int probeSize;
uniform float lodFactor;
uniform float lodMax;
uniform float intensityFac;
uniform float sampleCount;
in vec3 worldPosition;
out vec4 FragColor;
#define M_4PI 12.5663706143591729
const mat3 CUBE_ROTATIONS[6] = mat3[](
mat3(vec3(0.0, 0.0, -1.0), vec3(0.0, -1.0, 0.0), vec3(-1.0, 0.0, 0.0)),
mat3(vec3(0.0, 0.0, 1.0), vec3(0.0, -1.0, 0.0), vec3(1.0, 0.0, 0.0)),
mat3(vec3(1.0, 0.0, 0.0), vec3(0.0, 0.0, 1.0), vec3(0.0, -1.0, 0.0)),
mat3(vec3(1.0, 0.0, 0.0), vec3(0.0, 0.0, -1.0), vec3(0.0, 1.0, 0.0)),
mat3(vec3(1.0, 0.0, 0.0), vec3(0.0, -1.0, 0.0), vec3(0.0, 0.0, -1.0)),
mat3(vec3(-1.0, 0.0, 0.0), vec3(0.0, -1.0, 0.0), vec3(0.0, 0.0, 1.0)));
vec3 get_cubemap_vector(vec2 co, int face)
{
return normalize(CUBE_ROTATIONS[face] * vec3(co * 2.0 - 1.0, 1.0));
}
float area_element(float x, float y)
{
return atan(x * y, sqrt(x * x + y * y + 1));
}
float texel_solid_angle(vec2 co, float halfpix)
{
vec2 v1 = (co - vec2(halfpix)) * 2.0 - 1.0;
vec2 v2 = (co + vec2(halfpix)) * 2.0 - 1.0;
return area_element(v1.x, v1.y) - area_element(v1.x, v2.y) - area_element(v2.x, v1.y) +
area_element(v2.x, v2.y);
}
vec3 octahedral_to_cubemap_proj(vec2 co)
{
co = co * 2.0 - 1.0;
vec2 abs_co = abs(co);
vec3 v = vec3(co, 1.0 - (abs_co.x + abs_co.y));
if (abs_co.x + abs_co.y > 1.0) {
v.xy = (abs(co.yx) - 1.0) * -sign(co.xy);
}
return v;
}
void main()
{
#if defined(IRRADIANCE_SH_L2)
float pixstep = 1.0 / probeSize;
float halfpix = pixstep / 2.0;
/* Downside: leaks negative values, very bandwidth consuming */
int comp = int(gl_FragCoord.x) % 3 + (int(gl_FragCoord.y) % 3) * 3;
float weight_accum = 0.0;
vec3 sh = vec3(0.0);
for (int face = 0; face < 6; face++) {
for (float x = halfpix; x < 1.0; x += pixstep) {
for (float y = halfpix; y < 1.0; y += pixstep) {
float weight, coef;
vec2 facecoord = vec2(x, y);
vec3 cubevec = get_cubemap_vector(facecoord, face);
if (comp == 0) {
coef = 0.282095;
}
else if (comp == 1) {
coef = -0.488603 * cubevec.z * 2.0 / 3.0;
}
else if (comp == 2) {
coef = 0.488603 * cubevec.y * 2.0 / 3.0;
}
else if (comp == 3) {
coef = -0.488603 * cubevec.x * 2.0 / 3.0;
}
else if (comp == 4) {
coef = 1.092548 * cubevec.x * cubevec.z * 1.0 / 4.0;
}
else if (comp == 5) {
coef = -1.092548 * cubevec.z * cubevec.y * 1.0 / 4.0;
}
else if (comp == 6) {
coef = 0.315392 * (3.0 * cubevec.y * cubevec.y - 1.0) * 1.0 / 4.0;
}
else if (comp == 7) {
coef = -1.092548 * cubevec.x * cubevec.y * 1.0 / 4.0;
}
else { /* (comp == 8) */
coef = 0.546274 * (cubevec.x * cubevec.x - cubevec.z * cubevec.z) * 1.0 / 4.0;
}
weight = texel_solid_angle(facecoord, halfpix);
vec4 samp = textureLod(probeHdr, cubevec, lodMax);
sh += samp.rgb * coef * weight;
weight_accum += weight;
}
}
}
sh *= M_4PI / weight_accum;
FragColor = vec4(sh, 1.0);
#else
# if defined(IRRADIANCE_HL2)
/* Downside: very very low resolution (6 texels), bleed lighting because of interpolation */
int x = int(gl_FragCoord.x) % 3;
int y = int(gl_FragCoord.y) % 2;
vec3 cubevec = vec3(1.0, 0.0, 0.0);
if (x == 1) {
cubevec = cubevec.yxy;
}
else if (x == 2) {
cubevec = cubevec.yyx;
}
if (y == 1) {
cubevec = -cubevec;
}
# endif
vec3 N, T, B, V;
N = normalize(cubevec);
make_orthonormal_basis(N, T, B); /* Generate tangent space */
/* Integrating Envmap */
float weight = 0.0;
vec3 out_radiance = vec3(0.0);
for (float i = 0; i < sampleCount; i++) {
vec3 Xi = rand2d_to_cylinder(hammersley_2d(i, sampleCount));
float pdf;
vec3 L = sample_uniform_hemisphere(Xi, N, T, B, pdf);
float NL = dot(N, L);
if (NL > 0.0) {
/* Coarse Approximation of the mapping distortion
* Unit Sphere -> Cubemap Face */
const float dist = 4.0 * M_PI / 6.0;
/* http://http.developer.nvidia.com/GPUGems3/gpugems3_ch20.html : Equation 13 */
float lod = clamp(lodFactor - 0.5 * log2(pdf * dist), 0.0, lodMax);
out_radiance += textureLod(probeHdr, L, lod).rgb * NL;
weight += NL;
}
}
FragColor = irradiance_encode(intensityFac * out_radiance / weight);
#endif
}
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