Meshlet misc (#13761)

- Copy module docs so that they show up in the re-export
- Change meshlet_id to cluster_id in the debug visualization
- Small doc tweaks

crates/bevy_pbr/src/lib.rs

@@ -16,6 +16,7 @@ pub mod wireframe;
 /// Expect bugs, missing features, compatibility issues, low performance, and/or future breaking changes.
 #[cfg(feature = "meshlet")]
 pub mod experimental {
+    /// Render high-poly 3d meshes using an efficient GPU-driven method. See [`MeshletPlugin`] and [`MeshletMesh`] for details.
     pub mod meshlet {
         pub use crate::meshlet::*;
     }

crates/bevy_pbr/src/meshlet/meshlet_mesh_material.wgsl

@@ -18,7 +18,7 @@ fn vertex(@builtin(vertex_index) vertex_input: u32) -> @builtin(position) vec4<f
 @fragment
 fn fragment(@builtin(position) frag_coord: vec4<f32>) -> @location(0) vec4<f32> {
     let vertex_output = resolve_vertex_output(frag_coord);
-    var rng = vertex_output.meshlet_id;
+    var rng = vertex_output.cluster_id;
     let color = vec3(rand_f(&rng), rand_f(&rng), rand_f(&rng));
     return vec4(color, 1.0);
 }

crates/bevy_pbr/src/meshlet/mod.rs

@@ -95,7 +95,6 @@ const MESHLET_MESH_MATERIAL_SHADER_HANDLE: Handle<Shader> =
 /// Once meshes are pre-processed into a [`MeshletMesh`], this plugin can render these kinds of scenes very efficiently.
 ///
 /// In comparison to Bevy's standard renderer:
-/// * Minimal rendering work is done on the CPU. All rendering is GPU-driven.
 /// * Much more efficient culling. Meshlets can be culled individually, instead of all or nothing culling for entire meshes at a time.
 /// Additionally, occlusion culling can eliminate meshlets that would cause overdraw.
 /// * Much more efficient batching. All geometry can be rasterized in a single indirect draw.
@@ -104,7 +103,7 @@ const MESHLET_MESH_MATERIAL_SHADER_HANDLE: Handle<Shader> =
 /// * Much greater base overhead. Rendering will be slower than Bevy's standard renderer with small amounts of geometry and overdraw.
 /// * Much greater memory usage.
 /// * Requires preprocessing meshes. See [`MeshletMesh`] for details.
-/// * More limitations on the kinds of materials you can use. See [`MeshletMesh`] for details.
+/// * Limitations on the kinds of materials you can use. See [`MeshletMesh`] for details.
 ///
 /// This plugin is not compatible with [`Msaa`], and adding this plugin will disable it.
 ///

crates/bevy_pbr/src/meshlet/visibility_buffer_resolve.wgsl

@@ -85,7 +85,7 @@ struct VertexOutput {
     ddy_uv: vec2<f32>,
     world_tangent: vec4<f32>,
     mesh_flags: u32,
-    meshlet_id: u32,
+    cluster_id: u32,
 #ifdef PREPASS_FRAGMENT
 #ifdef MOTION_VECTOR_PREPASS
     motion_vector: vec2<f32>,
@@ -176,7 +176,7 @@ fn resolve_vertex_output(frag_coord: vec4<f32>) -> VertexOutput {
         ddy_uv,
         world_tangent,
         instance_uniform.flags,
-        meshlet_id,
+        cluster_id,
 #ifdef PREPASS_FRAGMENT
 #ifdef MOTION_VECTOR_PREPASS
         motion_vector,