Fix meshlet interactions with regular shading passes (#13816)

* Fixes https://github.com/bevyengine/bevy/issues/13813
* Fixes https://github.com/bevyengine/bevy/issues/13810

Tested a combined scene with both regular meshes and meshlet meshes
with:
* Regular forward setup
* Forward + normal/motion vector prepasses
* Deferred (with depth prepass since that's required) 
* Deferred + depth/normal/motion vector prepasses

Still broken:
* Using meshlet meshes rendering in deferred and regular meshes
rendering in forward + depth/normal prepass. I don't know how to fix
this at the moment, so for now I've just add instructions to not mix
them.

crates/bevy_core_pipeline/src/deferred/node.rs

@@ -122,17 +122,17 @@ impl ViewNode for DeferredGBufferPrepassNode {
         let view_entity = graph.view_entity();
         render_context.add_command_buffer_generation_task(move |render_device| {
             #[cfg(feature = "trace")]
-            let _deferred_span = info_span!("deferred").entered();
+            let _deferred_span = info_span!("deferred_prepass").entered();
 
             // Command encoder setup
             let mut command_encoder =
                 render_device.create_command_encoder(&CommandEncoderDescriptor {
-                    label: Some("deferred_command_encoder"),
+                    label: Some("deferred_prepass_command_encoder"),
                 });
 
             // Render pass setup
             let render_pass = command_encoder.begin_render_pass(&RenderPassDescriptor {
-                label: Some("deferred"),
+                label: Some("deferred_prepass"),
                 color_attachments: &color_attachments,
                 depth_stencil_attachment,
                 timestamp_writes: None,
@@ -148,20 +148,20 @@ impl ViewNode for DeferredGBufferPrepassNode {
                 || !opaque_deferred_phase.unbatchable_keys.is_empty()
             {
                 #[cfg(feature = "trace")]
-                let _opaque_prepass_span = info_span!("opaque_deferred").entered();
+                let _opaque_prepass_span = info_span!("opaque_deferred_prepass").entered();
                 opaque_deferred_phase.render(&mut render_pass, world, view_entity);
             }
 
             // Alpha masked draws
             if !alpha_mask_deferred_phase.is_empty() {
                 #[cfg(feature = "trace")]
-                let _alpha_mask_deferred_span = info_span!("alpha_mask_deferred").entered();
+                let _alpha_mask_deferred_span = info_span!("alpha_mask_deferred_prepass").entered();
                 alpha_mask_deferred_phase.render(&mut render_pass, world, view_entity);
             }
 
             drop(render_pass);
 
-            // Copy prepass depth to the main depth texture
+            // After rendering to the view depth texture, copy it to the prepass depth texture
             if let Some(prepass_depth_texture) = &view_prepass_textures.depth {
                 command_encoder.copy_texture_to_texture(
                     view_depth_texture.texture.as_image_copy(),

crates/bevy_core_pipeline/src/prepass/node.rs

@@ -162,7 +162,7 @@ impl ViewNode for PrepassNode {
             pass_span.end(&mut render_pass);
             drop(render_pass);
 
-            // Copy prepass depth to the main depth texture if deferred isn't going to
+            // After rendering to the view depth texture, copy it to the prepass depth texture if deferred isn't going to
             if deferred_prepass.is_none() {
                 if let Some(prepass_depth_texture) = &view_prepass_textures.depth {
                     command_encoder.copy_texture_to_texture(

crates/bevy_pbr/src/meshlet/material_draw_nodes.rs

@@ -10,8 +10,13 @@ use crate::{
     MeshViewBindGroup, PrepassViewBindGroup, ViewFogUniformOffset, ViewLightProbesUniformOffset,
     ViewLightsUniformOffset, ViewScreenSpaceReflectionsUniformOffset,
 };
-use bevy_core_pipeline::prepass::{PreviousViewUniformOffset, ViewPrepassTextures};
-use bevy_ecs::{query::QueryItem, world::World};
+use bevy_core_pipeline::prepass::{
+    MotionVectorPrepass, PreviousViewUniformOffset, ViewPrepassTextures,
+};
+use bevy_ecs::{
+    query::{Has, QueryItem},
+    world::World,
+};
 use bevy_render::{
     camera::ExtractedCamera,
     render_graph::{NodeRunError, RenderGraphContext, ViewNode},
@@ -138,7 +143,8 @@ impl ViewNode for MeshletPrepassNode {
         &'static ExtractedCamera,
         &'static ViewPrepassTextures,
         &'static ViewUniformOffset,
-        Option<&'static PreviousViewUniformOffset>,
+        &'static PreviousViewUniformOffset,
+        Has<MotionVectorPrepass>,
         &'static MeshletViewMaterialsPrepass,
         &'static MeshletViewBindGroups,
         &'static MeshletViewResources,
@@ -153,6 +159,7 @@ impl ViewNode for MeshletPrepassNode {
             view_prepass_textures,
             view_uniform_offset,
             previous_view_uniform_offset,
+            view_has_motion_vector_prepass,
             meshlet_view_materials,
             meshlet_view_bind_groups,
             meshlet_view_resources,
@@ -212,7 +219,7 @@ impl ViewNode for MeshletPrepassNode {
             render_pass.set_camera_viewport(viewport);
         }
 
-        if let Some(previous_view_uniform_offset) = previous_view_uniform_offset {
+        if view_has_motion_vector_prepass {
             render_pass.set_bind_group(
                 0,
                 prepass_view_bind_group.motion_vectors.as_ref().unwrap(),
@@ -259,7 +266,8 @@ impl ViewNode for MeshletDeferredGBufferPrepassNode {
         &'static ExtractedCamera,
         &'static ViewPrepassTextures,
         &'static ViewUniformOffset,
-        Option<&'static PreviousViewUniformOffset>,
+        &'static PreviousViewUniformOffset,
+        Has<MotionVectorPrepass>,
         &'static MeshletViewMaterialsDeferredGBufferPrepass,
         &'static MeshletViewBindGroups,
         &'static MeshletViewResources,
@@ -274,6 +282,7 @@ impl ViewNode for MeshletDeferredGBufferPrepassNode {
             view_prepass_textures,
             view_uniform_offset,
             previous_view_uniform_offset,
+            view_has_motion_vector_prepass,
             meshlet_view_materials,
             meshlet_view_bind_groups,
             meshlet_view_resources,
@@ -338,7 +347,7 @@ impl ViewNode for MeshletDeferredGBufferPrepassNode {
             render_pass.set_camera_viewport(viewport);
         }
 
-        if let Some(previous_view_uniform_offset) = previous_view_uniform_offset {
+        if view_has_motion_vector_prepass {
             render_pass.set_bind_group(
                 0,
                 prepass_view_bind_group.motion_vectors.as_ref().unwrap(),

crates/bevy_pbr/src/meshlet/material_draw_prepare.rs

@@ -142,7 +142,8 @@ pub fn prepare_material_meshlet_meshes_main_opaque_pass<M: Material>(
                 continue;
             };
 
-            if material.properties.alpha_mode != AlphaMode::Opaque
+            if material.properties.render_method != OpaqueRendererMethod::Forward
+                || material.properties.alpha_mode != AlphaMode::Opaque
                 || material.properties.reads_view_transmission_texture
             {
                 continue;

crates/bevy_pbr/src/meshlet/mod.rs

@@ -109,6 +109,10 @@ const MESHLET_MESH_MATERIAL_SHADER_HANDLE: Handle<Shader> =
 ///
 /// This plugin does not work on WASM.
 ///
+/// Mixing forward+prepass and deferred rendering for opaque materials is not currently supported when using this plugin.
+/// You must use one or the other by setting [`crate::DefaultOpaqueRendererMethod`].
+/// Do not override [`crate::Material::opaque_render_method`] for any material when using this plugin.
+///
 /// ![A render of the Stanford dragon as a `MeshletMesh`](https://raw.githubusercontent.com/bevyengine/bevy/main/crates/bevy_pbr/src/meshlet/meshlet_preview.png)
 pub struct MeshletPlugin;
 
@@ -206,18 +210,18 @@ impl Plugin for MeshletPlugin {
             .add_render_graph_edges(
                 Core3d,
                 (
-                    // TODO: Meshlet VisibilityBufferRaster should be after main pass when not using depth prepass
+                    // Non-meshlet shading passes _must_ come before meshlet shading passes
                     NodePbr::ShadowPass,
-                    Node3d::Prepass,
-                    Node3d::DeferredPrepass,
                     NodeMeshlet::VisibilityBufferRasterPass,
                     NodeMeshlet::Prepass,
+                    Node3d::Prepass,
                     NodeMeshlet::DeferredPrepass,
+                    Node3d::DeferredPrepass,
                     Node3d::CopyDeferredLightingId,
                     Node3d::EndPrepasses,
                     Node3d::StartMainPass,
-                    Node3d::MainOpaquePass,
                     NodeMeshlet::MainOpaquePass,
+                    Node3d::MainOpaquePass,
                     Node3d::EndMainPass,
                 ),
             )