Stop copying the light probe array to the stack in the shader. (#11805)

This was causing a severe performance regression when light probes were
enabled.

Fixes #11787.

crates/bevy_pbr/src/light_probe/environment_map.wgsl

@@ -30,10 +30,7 @@ fn compute_radiances(
  var radiances: EnvironmentMapRadiances;
 
  // Search for a reflection probe that contains the fragment.
- var query_result = query_light_probe(
- light_probes.reflection_probes,
- light_probes.reflection_probe_count,
- world_position);
+ var query_result = query_light_probe(world_position, /*is_irradiance_volume=*/ false);
 
  // If we didn't find a reflection probe, use the view environment map if applicable.
  if (query_result.texture_index < 0) {

crates/bevy_pbr/src/light_probe/irradiance_volume.wgsl

@@ -13,10 +13,7 @@
 // Slide 28, "Ambient Cube Basis"
 fn irradiance_volume_light(world_position: vec3<f32>, N: vec3<f32>) -> vec3<f32> {
  // Search for an irradiance volume that contains the fragment.
- let query_result = query_light_probe(
- light_probes.irradiance_volumes,
- light_probes.irradiance_volume_count,
- world_position);
+ let query_result = query_light_probe(world_position, /*is_irradiance_volume=*/ true);
 
  // If there was no irradiance volume found, bail out.
  if (query_result.texture_index < 0) {

crates/bevy_pbr/src/light_probe/light_probe.wgsl

@@ -1,5 +1,6 @@
 #define_import_path bevy_pbr::light_probe
 
+#import bevy_pbr::mesh_view_bindings::light_probes
 #import bevy_pbr::mesh_view_types::LightProbe
 
 // The result of searching for a light probe.
@@ -28,20 +29,28 @@ fn transpose_affine_matrix(matrix: mat3x4<f32>) -> mat4x4<f32> {
 //
 // TODO: Interpolate between multiple light probes.
 fn query_light_probe(
- in_light_probes: array<LightProbe, 8u>,
- light_probe_count: i32,
  world_position: vec3<f32>,
+ is_irradiance_volume: bool,
 ) -> LightProbeQueryResult {
- // This is needed to index into the array with a non-constant expression.
- var light_probes = in_light_probes;
-
  var result: LightProbeQueryResult;
  result.texture_index = -1;
 
+ var light_probe_count: i32;
+ if is_irradiance_volume {
+ light_probe_count = light_probes.irradiance_volume_count;
+ } else {
+ light_probe_count = light_probes.reflection_probe_count;
+ }
+
  for (var light_probe_index: i32 = 0;
  light_probe_index < light_probe_count && result.texture_index < 0;
  light_probe_index += 1) {
- let light_probe = light_probes[light_probe_index];
+ var light_probe: LightProbe;
+ if is_irradiance_volume {
+ light_probe = light_probes.irradiance_volumes[light_probe_index];
+ } else {
+ light_probe = light_probes.reflection_probes[light_probe_index];
+ }
 
  // Unpack the inverse transform.
  let inverse_transform =