Fix deferred rendering (#15656)

# Objective

Fixes #15525

The deferred and mesh pipelines tonemapping LUT bindings were
accidentally out of sync, breaking deferred rendering.

As noted in the issue it's still broken on wasm due to hitting a texture
limit.

## Solution

Add constants for these instead of hardcoding them.

## Testing

Test with `cargo run --example deferred_rendering` and see it works, run
the same on main and see it crash.

crates/bevy_pbr/src/deferred/mod.rs

@@ -2,7 +2,8 @@ use crate::{
  graph::NodePbr, irradiance_volume::IrradianceVolume, prelude::EnvironmentMapLight,
  MeshPipeline, MeshViewBindGroup, RenderViewLightProbes, ScreenSpaceAmbientOcclusion,
  ScreenSpaceReflectionsUniform, ViewEnvironmentMapUniformOffset, ViewLightProbesUniformOffset,
- ViewScreenSpaceReflectionsUniformOffset,
+ ViewScreenSpaceReflectionsUniformOffset, TONEMAPPING_LUT_SAMPLER_BINDING_INDEX,
+ TONEMAPPING_LUT_TEXTURE_BINDING_INDEX,
 };
 use bevy_app::prelude::*;
 use bevy_asset::{load_internal_asset, Handle};
@@ -259,11 +260,11 @@ impl SpecializedRenderPipeline for DeferredLightingLayout {
  shader_defs.push("TONEMAP_IN_SHADER".into());
  shader_defs.push(ShaderDefVal::UInt(
  "TONEMAPPING_LUT_TEXTURE_BINDING_INDEX".into(),
- 22,
+ TONEMAPPING_LUT_TEXTURE_BINDING_INDEX,
  ));
  shader_defs.push(ShaderDefVal::UInt(
  "TONEMAPPING_LUT_SAMPLER_BINDING_INDEX".into(),
- 23,
+ TONEMAPPING_LUT_SAMPLER_BINDING_INDEX,
  ));
 
  let method = key.intersection(MeshPipelineKey::TONEMAP_METHOD_RESERVED_BITS);

crates/bevy_pbr/src/lib.rs

@@ -158,6 +158,9 @@ pub const RGB9E5_FUNCTIONS_HANDLE: Handle<Shader> = Handle::weak_from_u128(26590
 const MESHLET_VISIBILITY_BUFFER_RESOLVE_SHADER_HANDLE: Handle<Shader> =
  Handle::weak_from_u128(2325134235233421);
 
+const TONEMAPPING_LUT_TEXTURE_BINDING_INDEX: u32 = 23;
+const TONEMAPPING_LUT_SAMPLER_BINDING_INDEX: u32 = 24;
+
 /// Sets up the entire PBR infrastructure of bevy.
 pub struct PbrPlugin {
  /// Controls if the prepass is enabled for the [`StandardMaterial`].

crates/bevy_pbr/src/render/mesh.rs

@@ -1842,11 +1842,11 @@ impl SpecializedMeshPipeline for MeshPipeline {
  shader_defs.push("TONEMAP_IN_SHADER".into());
  shader_defs.push(ShaderDefVal::UInt(
  "TONEMAPPING_LUT_TEXTURE_BINDING_INDEX".into(),
- 23,
+ TONEMAPPING_LUT_TEXTURE_BINDING_INDEX,
  ));
  shader_defs.push(ShaderDefVal::UInt(
  "TONEMAPPING_LUT_SAMPLER_BINDING_INDEX".into(),
- 24,
+ TONEMAPPING_LUT_SAMPLER_BINDING_INDEX,
  ));
 
  let method = key.intersection(MeshPipelineKey::TONEMAP_METHOD_RESERVED_BITS);