Move some code into MeshletGpuScene, skip unused material draws

crates/bevy_pbr/src/meshlet/gpu_scene.rs

@@ -31,6 +31,7 @@ use bevy_transform::components::GlobalTransform;
 use bevy_utils::{tracing::error, EntityHashMap, HashMap};
 use std::{
     hash::Hash,
+    mem,
     ops::{DerefMut, Range},
     sync::Arc,
 };
@@ -607,25 +608,39 @@ impl MeshletGpuScene {
         &self.draw_bind_group_layout
     }
 
-    pub fn resources_for_view(
-        &self,
+    pub fn resources_for_view<'a>(
+        &'a self,
         view_entity: Entity,
+        pipeline_cache: &'a PipelineCache,
     ) -> (
         u32,
-        Vec<Option<&(CachedRenderPipelineId, BindGroup)>>,
+        impl Iterator<Item = (u64, &'a BindGroup, &'a RenderPipeline)>,
         Option<&BindGroup>,
         Option<&BindGroup>,
         Option<&Buffer>,
         Option<&Buffer>,
     ) {
-        let mut materials = Vec::new();
-        for material_id in &self.material_order {
-            materials.push(self.materials.get(&(*material_id, view_entity)));
-        }
+        let material_draws = self
+            .material_order
+            .iter()
+            .enumerate()
+            .filter(|(_, material_id)| self.material_vertex_counts.contains_key(*material_id))
+            .map(move |(i, material_id)| (i, &self.materials[&(*material_id, view_entity)]))
+            .filter_map(|(i, (material_pipeline_id, material_bind_group))| {
+                pipeline_cache
+                    .get_render_pipeline(*material_pipeline_id)
+                    .map(|material_pipeline| {
+                        (
+                            (i * mem::size_of::<DrawIndexedIndirect>()) as u64,
+                            material_bind_group,
+                            material_pipeline,
+                        )
+                    })
+            });
 
         (
             self.scene_meshlet_count,
-            materials,
+            material_draws,
             self.culling_bind_groups.get(&view_entity),
             self.draw_bind_groups.get(&view_entity),
             self.draw_index_buffer.as_ref(),

crates/bevy_pbr/src/meshlet/node.rs

@@ -61,12 +61,12 @@ impl ViewNode for MainMeshletOpaquePass3dNode {
         };
         let (
             scene_meshlet_count,
-            materials,
+            material_draws,
             Some(culling_bind_group),
             Some(draw_bind_group),
             Some(draw_index_buffer),
             Some(draw_command_buffer),
-        ) = gpu_scene.resources_for_view(graph.view_entity())
+        ) = gpu_scene.resources_for_view(graph.view_entity(), pipeline_cache)
         else {
             return Ok(());
         };
@@ -131,17 +131,10 @@ impl ViewNode for MainMeshletOpaquePass3dNode {
             );
             draw_pass.set_bind_group(1, draw_bind_group, &[]);
 
-            // TODO: Move this code into MeshletGpuScene::resources(), and have that return an iterator over
-            // (draw_offset, pipeline, material_bind_group)
-            // TODO: Skip indirect draw if 0 vertex count for material
-            for (i, material_resources) in materials.iter().enumerate() {
-                if let Some((pipeline_id, material_bind_group)) = material_resources {
-                    if let Some(pipeline) = pipeline_cache.get_render_pipeline(*pipeline_id) {
-                        draw_pass.set_bind_group(2, material_bind_group, &[]);
-                        draw_pass.set_render_pipeline(pipeline);
-                        draw_pass.draw_indexed_indirect(draw_command_buffer, i as u64 * 20);
-                    }
-                }
+            for (material_draw_offset, material_bind_group, material_pipeline) in material_draws {
+                draw_pass.set_bind_group(2, material_bind_group, &[]);
+                draw_pass.set_render_pipeline(material_pipeline);
+                draw_pass.draw_indexed_indirect(draw_command_buffer, material_draw_offset);
             }
         }