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Merge pull request #54919 from williamd67/GPULightmapper-improve-noise-to-prevent-artifacts

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GPULightmapper: better algorithm to generate rays for indirect lighting
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JFonS 2021-11-22 12:10:09 +01:00 committed by GitHub
commit ea8d0deb4b
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 35 additions and 13 deletions
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48
modules/lightmapper_rd/lm_compute.glsl
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@ -235,19 +235,39 @@ uint trace_ray(vec3 p_from, vec3 p_to
return RAY_MISS;
}
const float PI = 3.14159265f;
const float GOLDEN_ANGLE = PI * (3.0 - sqrt(5.0));
vec3 vogel_hemisphere(uint p_index, uint p_count, float p_offset) {
float r = sqrt(float(p_index) + 0.5f) / sqrt(float(p_count));
float theta = float(p_index) * GOLDEN_ANGLE + p_offset;
float y = cos(r * PI * 0.5);
float l = sin(r * PI * 0.5);
return vec3(l * cos(theta), l * sin(theta), y);
// https://www.reedbeta.com/blog/hash-functions-for-gpu-rendering/
uint hash(uint value) {
uint state = value * 747796405u + 2891336453u;
uint word = ((state >> ((state >> 28u) + 4u)) ^ state) * 277803737u;
return (word >> 22u) ^ word;
}
float quick_hash(vec2 pos) {
return fract(sin(dot(pos * 19.19, vec2(49.5791, 97.413))) * 49831.189237);
uint random_seed(ivec3 seed) {
return hash(seed.x ^ hash(seed.y ^ hash(seed.z)));
}
// generates a random value in range [0.0, 1.0)
float randomize(inout uint value) {
value = hash(value);
return float(value / 4294967296.0);
}
const float PI = 3.14159265f;
// http://www.realtimerendering.com/raytracinggems/unofficial_RayTracingGems_v1.4.pdf (chapter 15)
vec3 generate_hemisphere_uniform_direction(inout uint noise) {
float noise1 = randomize(noise);
float noise2 = randomize(noise) * 2.0 * PI;
float factor = sqrt(1 - (noise1 * noise1));
return vec3(factor * cos(noise2), factor * sin(noise2), noise1);
}
vec3 generate_hemisphere_cosine_weighted_direction(inout uint noise) {
float noise1 = randomize(noise);
float noise2 = randomize(noise) * 2.0 * PI;
return vec3(sqrt(noise1) * cos(noise2), sqrt(noise1) * sin(noise2), sqrt(1.0 - noise1));
}
float get_omni_attenuation(float distance, float inv_range, float decay) {
@ -404,8 +424,9 @@ void main() {
#endif
vec3 light_average = vec3(0.0);
float active_rays = 0.0;
uint noise = random_seed(ivec3(params.ray_from, atlas_pos));
for (uint i = params.ray_from; i < params.ray_to; i++) {
vec3 ray_dir = normal_mat * vogel_hemisphere(i, params.ray_count, quick_hash(vec2(atlas_pos)));
vec3 ray_dir = normal_mat * generate_hemisphere_cosine_weighted_direction(noise);
uint tidx;
vec3 barycentric;
@ -550,8 +571,9 @@ void main() {
vec4(0.0),
vec4(0.0));
uint noise = random_seed(ivec3(params.ray_from, probe_index, 49502741 /* some prime */));
for (uint i = params.ray_from; i < params.ray_to; i++) {
vec3 ray_dir = vogel_hemisphere(i, params.ray_count, quick_hash(vec2(float(probe_index), 0.0)));
vec3 ray_dir = generate_hemisphere_uniform_direction(noise);
if (bool(i & 1)) {
//throw to both sides, so alternate them
ray_dir.z *= -1.0;