From 175e1462289c217ec57a3d3b9894a7c513890fa4 Mon Sep 17 00:00:00 2001
From: JMS55 <47158642+JMS55@users.noreply.github.com>
Date: Thu, 6 Jun 2024 10:10:07 -0700
Subject: [PATCH] Misc meshlet changes (#13705)

* Rename cull_meshlets -> cull_clusters
* Rename meshlet_visible -> cluster_visible
* Add an if statement around meshlet_second_pass_candidates writes,
maybe a small bit of performance.
---
 .../{cull_meshlets.wgsl => cull_clusters.wgsl}   | 16 +++++++++-------
 crates/bevy_pbr/src/meshlet/mod.rs               |  2 +-
 crates/bevy_pbr/src/meshlet/pipelines.rs         |  4 ++--
 3 files changed, 12 insertions(+), 10 deletions(-)
 rename crates/bevy_pbr/src/meshlet/{cull_meshlets.wgsl => cull_clusters.wgsl} (96%)

diff --git a/crates/bevy_pbr/src/meshlet/cull_meshlets.wgsl b/crates/bevy_pbr/src/meshlet/cull_clusters.wgsl
similarity index 96%
rename from crates/bevy_pbr/src/meshlet/cull_meshlets.wgsl
rename to crates/bevy_pbr/src/meshlet/cull_clusters.wgsl
index e25532b319..373b1e411d 100644
--- a/crates/bevy_pbr/src/meshlet/cull_meshlets.wgsl
+++ b/crates/bevy_pbr/src/meshlet/cull_clusters.wgsl
@@ -22,7 +22,7 @@
 
 @compute
 @workgroup_size(128, 1, 1) // 128 threads per workgroup, 1 cluster per thread
-fn cull_meshlets(
+fn cull_clusters(
     @builtin(workgroup_id) workgroup_id: vec3<u32>,
     @builtin(num_workgroups) num_workgroups: vec3<u32>,
     @builtin(local_invocation_id) local_invocation_id: vec3<u32>,
@@ -100,25 +100,27 @@ fn cull_meshlets(
     let occluder_depth = min(min(depth_quad_a, depth_quad_b), min(depth_quad_c, depth_quad_d));
 
     // Check whether or not the cluster would be occluded if drawn
-    var meshlet_visible: bool;
+    var cluster_visible: bool;
     if view.clip_from_view[3][3] == 1.0 {
         // Orthographic
         let sphere_depth = view.clip_from_view[3][2] + (culling_bounding_sphere_center_view_space.z + culling_bounding_sphere_radius) * view.clip_from_view[2][2];
-        meshlet_visible = sphere_depth >= occluder_depth;
+        cluster_visible = sphere_depth >= occluder_depth;
     } else {
         // Perspective
         let sphere_depth = -view.clip_from_view[3][2] / (culling_bounding_sphere_center_view_space.z + culling_bounding_sphere_radius);
-        meshlet_visible = sphere_depth >= occluder_depth;
+        cluster_visible = sphere_depth >= occluder_depth;
     }
 
     // Write if the cluster should be occlusion tested in the second pass
 #ifdef MESHLET_FIRST_CULLING_PASS
-    let second_pass_candidate = u32(!meshlet_visible) << cluster_id % 32u;
-    atomicOr(&meshlet_second_pass_candidates[cluster_id / 32u], second_pass_candidate);
+    if !cluster_visible {
+        let bit = 1u << cluster_id % 32u;
+        atomicOr(&meshlet_second_pass_candidates[cluster_id / 32u], bit);
+    }
 #endif
 
     // Append a list of this cluster's triangles to draw if not culled
-    if meshlet_visible {
+    if cluster_visible {
         let meshlet_triangle_count = meshlets[meshlet_id].triangle_count;
         let buffer_start = atomicAdd(&draw_indirect_args.vertex_count, meshlet_triangle_count * 3u) / 3u;
         let cluster_id_packed = cluster_id << 6u;
diff --git a/crates/bevy_pbr/src/meshlet/mod.rs b/crates/bevy_pbr/src/meshlet/mod.rs
index 69255f9084..fd73e35c4a 100644
--- a/crates/bevy_pbr/src/meshlet/mod.rs
+++ b/crates/bevy_pbr/src/meshlet/mod.rs
@@ -136,7 +136,7 @@ impl Plugin for MeshletPlugin {
         load_internal_asset!(
             app,
             MESHLET_CULLING_SHADER_HANDLE,
-            "cull_meshlets.wgsl",
+            "cull_clusters.wgsl",
             Shader::from_wgsl
         );
         load_internal_asset!(
diff --git a/crates/bevy_pbr/src/meshlet/pipelines.rs b/crates/bevy_pbr/src/meshlet/pipelines.rs
index 2feaf9518b..0112dcbb67 100644
--- a/crates/bevy_pbr/src/meshlet/pipelines.rs
+++ b/crates/bevy_pbr/src/meshlet/pipelines.rs
@@ -67,7 +67,7 @@ impl FromWorld for MeshletPipelines {
                     "MESHLET_CULLING_PASS".into(),
                     "MESHLET_FIRST_CULLING_PASS".into(),
                 ],
-                entry_point: "cull_meshlets".into(),
+                entry_point: "cull_clusters".into(),
             }),
 
             cull_second: pipeline_cache.queue_compute_pipeline(ComputePipelineDescriptor {
@@ -79,7 +79,7 @@ impl FromWorld for MeshletPipelines {
                     "MESHLET_CULLING_PASS".into(),
                     "MESHLET_SECOND_CULLING_PASS".into(),
                 ],
-                entry_point: "cull_meshlets".into(),
+                entry_point: "cull_clusters".into(),
             }),
 
             downsample_depth_first: pipeline_cache.queue_compute_pipeline(