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Solari: Specular path spread heuristic #22311

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Merged
alice-i-cecile merged 4 commits into from
Dec 30, 2025
Merged

Solari: Specular path spread heuristic #22311

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db69e9a
Solari: Specular path spread heuristic
JMS55 Dec 30, 2025
2470fb9
Fixes
JMS55 Dec 30, 2025
598e9ea
Misc
JMS55 Dec 30, 2025
22910c9
Merge branch 'main' into solari6-specular-path-spread
JMS55 Dec 30, 2025
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7 changes: 4 additions & 3 deletions crates/bevy_solari/src/realtime/specular_gi.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ struct PushConstants { frame_index: u32, reset: u32 }
var<push_constant> constants: PushConstants;

const DIFFUSE_GI_REUSE_ROUGHNESS_THRESHOLD: f32 = 0.4;
const TERMINATE_IN_WORLD_CACHE_THRESHOLD: f32 = 0.3;
const TERMINATE_IN_WORLD_CACHE_THRESHOLD: f32 = 0.03;

@compute @workgroup_size(8, 8, 1)
fn specular_gi(@builtin(global_invocation_id) global_id: vec3<u32>) {
Expand All @@ -31,6 +31,7 @@ fn specular_gi(@builtin(global_invocation_id) global_id: vec3<u32>) {
}
let surface = gpixel_resolve(textureLoad(gbuffer, global_id.xy, 0), depth, global_id.xy, view.main_pass_viewport.zw, view.world_from_clip);

let wo_unnormalized = view.world_position - surface.world_position;
let wo = normalize(view.world_position - surface.world_position);

var radiance: vec3<f32>;
Expand All @@ -53,7 +54,7 @@ fn specular_gi(@builtin(global_invocation_id) global_id: vec3<u32>) {

// https://d1qx31qr3h6wln.cloudfront.net/publications/mueller21realtime.pdf#subsection.3.4, equation (4)
let cos_theta = saturate(dot(wo, surface.world_normal));
var a0 = dot(wi, wi) / (4.0 * PI * cos_theta);
var a0 = dot(wo_unnormalized, wo_unnormalized) / (4.0 * PI * cos_theta);
a0 *= TERMINATE_IN_WORLD_CACHE_THRESHOLD;

radiance = trace_glossy_path(surface.world_position, wi, pdf, a0, &rng) / pdf;
Expand Down Expand Up @@ -106,7 +107,7 @@ fn trace_glossy_path(initial_ray_origin: vec3<f32>, initial_wi: vec3<f32>, initi
surface_perfectly_specular = ray_hit.material.roughness <= 0.001 && ray_hit.material.metallic > 0.9999;

// https://d1qx31qr3h6wln.cloudfront.net/publications/mueller21realtime.pdf#subsection.3.4, equation (3)
path_spread += sqrt((ray.t * ray.t) / (p_bounce * saturate(dot(wo, N))));
path_spread += sqrt((ray.t * ray.t) / (p_bounce * wo_tangent.z));

if path_spread * path_spread > a0 * get_cell_size(ray_hit.world_position, view.world_position) {
// Path spread is wide enough, terminate path in the world cache
Expand Down
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