Use shader_def for oit resolve layer count (#15747)

# Objective

- Size is currently hardcoded in the shader which means it will break if
a user uses anything higher than that.

## Solution

- Use a shader_def to define the size

## Testing

Tested with the OIT example

crates/bevy_core_pipeline/src/oit/resolve/mod.rs

@@ -15,7 +15,7 @@ use bevy_render::{
  BindGroup, BindGroupEntries, BindGroupLayout, BindGroupLayoutEntries, BlendComponent,
  BlendState, CachedRenderPipelineId, ColorTargetState, ColorWrites, DownlevelFlags,
  FragmentState, MultisampleState, PipelineCache, PrimitiveState, RenderPipelineDescriptor,
- Shader, ShaderStages, TextureFormat,
+ Shader, ShaderDefVal, ShaderStages, TextureFormat,
  },
  renderer::{RenderAdapter, RenderDevice},
  texture::BevyDefault,
@@ -121,22 +121,33 @@ pub struct OitResolvePipelineId(pub CachedRenderPipelineId);
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub struct OitResolvePipelineKey {
  hdr: bool,
+ layer_count: u8,
 }
 
 #[allow(clippy::too_many_arguments)]
 pub fn queue_oit_resolve_pipeline(
  mut commands: Commands,
  pipeline_cache: Res<PipelineCache>,
  resolve_pipeline: Res<OitResolvePipeline>,
- views: Query<(Entity, &ExtractedView), With<OrderIndependentTransparencySettings>>,
+ views: Query<
+ (
+ Entity,
+ &ExtractedView,
+ &OrderIndependentTransparencySettings,
+ ),
+ With<OrderIndependentTransparencySettings>,
+ >,
  // Store the key with the id to make the clean up logic easier.
  // This also means it will always replace the entry if the key changes so nothing to clean up.
  mut cached_pipeline_id: Local<EntityHashMap<(OitResolvePipelineKey, CachedRenderPipelineId)>>,
 ) {
  let mut current_view_entities = EntityHashSet::default();
- for (e, view) in &views {
+ for (e, view, oit_settings) in &views {
  current_view_entities.insert(e);
- let key = OitResolvePipelineKey { hdr: view.hdr };
+ let key = OitResolvePipelineKey {
+ hdr: view.hdr,
+ layer_count: oit_settings.layer_count,
+ };
 
  if let Some((cached_key, id)) = cached_pipeline_id.get(&e) {
  if *cached_key == key {
@@ -179,7 +190,10 @@ fn specialize_oit_resolve_pipeline(
  fragment: Some(FragmentState {
  entry_point: "fragment".into(),
  shader: OIT_RESOLVE_SHADER_HANDLE,
- shader_defs: vec![],
+ shader_defs: vec![ShaderDefVal::UInt(
+ "LAYER_COUNT".into(),
+ key.layer_count as u32,
+ )],
  targets: vec![Some(ColorTargetState {
  format,
  blend: Some(BlendState {

crates/bevy_core_pipeline/src/oit/resolve/oit_resolve.wgsl

@@ -12,8 +12,7 @@ struct OitFragment {
  depth: f32,
 }
 // Contains all the colors and depth for this specific fragment
-// TODO don't hardcode size
-var<private> fragment_list: array<OitFragment, 32>;
+var<private> fragment_list: array<OitFragment, #{LAYER_COUNT}>;
 
 struct FullscreenVertexOutput {
  @builtin(position) position: vec4<f32>,