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/**
* The resources expected to be defined are:
* - probes_buf
* - lightprobe_cube_tx
* - cubes
*/
#pragma BLENDER_REQUIRE(common_math_geom_lib.glsl)
float lightprobe_cubemap_weight(CubemapData cube, vec3 P)
{
/* Composed transform to remove the packed data. */
vec3 lP = transform_direction(cube.influence_mat, P) + cube.influence_mat[3].xyz;
float attenuation;
if (cube._attenuation_type == CUBEMAP_SHAPE_SPHERE) {
attenuation = saturate(cube._attenuation_factor * (1.0 - length(lP)));
}
else {
attenuation = min_v3(saturate(cube._attenuation_factor * (1.0 - abs(lP))));
}
return attenuation;
}
vec3 lightprobe_cubemap_evaluate(CubemapInfoData info,
samplerCubeArray cubemap_tx,
CubemapData cube,
vec3 P,
vec3 R,
float roughness)
{
float linear_roughness = fast_sqrt(roughness);
if (cube._layer > 0.0) {
/* Correct reflection ray using parallax volume intersection. */
vec3 lR = transform_direction(cube.parallax_mat, R);
/* Composed transform to remove the packed data. */
vec3 lP = transform_direction(cube.parallax_mat, P) + cube.parallax_mat[3].xyz;
float dist;
if (cube._parallax_type == CUBEMAP_SHAPE_SPHERE) {
dist = line_unit_sphere_intersect_dist(lP, lR);
}
else {
dist = line_unit_box_intersect_dist(lP, lR);
}
vec3 cube_pos = vec3(cube._world_position_x, cube._world_position_y, cube._world_position_z);
/* Use Distance in WS directly to recover intersection. */
vec3 intersection = (P + R * dist) - cube_pos;
/* Distance based roughness from Frostbite PBR Course.
* http://www.frostbite.com/wp-content/uploads/2014/11/course_notes_moving_frostbite_to_pbr.pdf
*/
float original_roughness = roughness;
float distance_roughness = saturate(dist * linear_roughness / length(intersection));
linear_roughness = mix(distance_roughness, linear_roughness, linear_roughness);
roughness = linear_roughness * linear_roughness;
float fac = saturate(original_roughness * 2.0 - 1.0);
R = mix(intersection, R, fac * fac);
}
else {
R = transform_direction(info.lookdev_rotation, R);
}
float lod = linear_roughness * info.roughness_max_lod;
return textureLod(cubemap_tx, vec4(R, cube._layer), lod).rgb;
}
vec3 lightprobe_cubemap_eval(vec3 P, vec3 R, float roughness, float random_threshold)
{
/* Go through all cubemaps, computing and adding their weights for this pixel
* until reaching a random threshold. */
float weight = 0.0;
int cube_index = probes_buf.cubes_info.cube_count - 1;
for (; cube_index > 0; cube_index--) {
weight += lightprobe_cubemap_weight(cubes_buf[cube_index], P);
if (weight >= random_threshold) {
break;
}
}
return lightprobe_cubemap_evaluate(
probes_buf.cubes_info, lightprobe_cube_tx, cubes_buf[cube_index], P, R, roughness);
}
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