bevy_pbr: Use storage buffers for point lights if supported

Author: superdump

crates/bevy_pbr/src/lib.rs

@@ -41,6 +41,7 @@ use bevy_render::{
     render_graph::RenderGraph,
     render_phase::{sort_phase_system, AddRenderCommand, DrawFunctions},
     render_resource::{Shader, SpecializedMeshPipelines},
+    renderer::RenderDevice,
     view::VisibilitySystems,
     RenderApp, RenderStage,
 };
@@ -126,6 +127,15 @@ impl Plugin for PbrPlugin {
                 },
             );
 
+        // NOTE: 3 storage buffer bindings are needed for clustered-forward rendering so check
+        // that at least that many are supported
+        let use_storage_buffers = app
+            .world
+            .resource::<RenderDevice>()
+            .limits()
+            .max_storage_buffers_per_shader_stage
+            >= 3;
+
         let render_app = match app.get_sub_app_mut(RenderApp) {
             Ok(render_app) => render_app,
             Err(_) => return,
@@ -164,7 +174,7 @@ impl Plugin for PbrPlugin {
             .init_resource::<ShadowPipeline>()
             .init_resource::<DrawFunctions<Shadow>>()
             .init_resource::<LightMeta>()
-            .init_resource::<GlobalLightMeta>()
+            .insert_resource(GlobalLightMeta::new(use_storage_buffers))
             .init_resource::<SpecializedMeshPipelines<ShadowPipeline>>();
 
         let shadow_pass_node = ShadowPassNode::new(&mut render_app.world);

crates/bevy_pbr/src/light.rs

@@ -9,6 +9,7 @@ use bevy_render::{
     color::Color,
     prelude::Image,
     primitives::{Aabb, CubemapFrusta, Frustum, Sphere},
+    renderer::RenderDevice,
     view::{ComputedVisibility, RenderLayers, Visibility, VisibleEntities},
 };
 use bevy_transform::components::GlobalTransform;
@@ -709,6 +710,7 @@ pub(crate) fn assign_lights_to_clusters(
     lights_query: Query<(Entity, &GlobalTransform, &PointLight, &Visibility)>,
     mut lights: Local<Vec<PointLightAssignmentData>>,
     mut max_point_lights_warning_emitted: Local<bool>,
+    render_device: Res<RenderDevice>,
 ) {
     global_lights.entities.clear();
     lights.clear();
@@ -727,7 +729,10 @@ pub(crate) fn assign_lights_to_clusters(
             ),
     );
 
-    if lights.len() > MAX_POINT_LIGHTS {
+    // NOTE: Clustered-forward rendering requires 3 buffer bindings so only use storage buffers
+    // if at least 3 are supported
+    let use_storage_buffers = render_device.limits().max_storage_buffers_per_shader_stage >= 3;
+    if !use_storage_buffers && lights.len() > MAX_POINT_LIGHTS {
         lights.sort_by(|light_1, light_2| {
             point_light_order(
                 (&light_1.entity, &light_1.shadows_enabled),

crates/bevy_pbr/src/pbr_material.rs

@@ -357,6 +357,7 @@ impl RenderAsset for StandardMaterial {
 pub struct StandardMaterialKey {
     normal_map: bool,
     cull_mode: Option<Face>,
+    use_storage_buffers: bool,
 }
 
 impl SpecializedMaterial for StandardMaterial {
@@ -369,6 +370,9 @@ impl SpecializedMaterial for StandardMaterial {
         StandardMaterialKey {
             normal_map: render_asset.has_normal_map,
             cull_mode: render_asset.cull_mode,
+            // NOTE: Clustered-forward rendering requires 3 storage buffer bindings so check that
+            // at least that many are supported.
+            use_storage_buffers: render_device.limits().max_storage_buffers_per_shader_stage >= 3,
         }
     }
 
@@ -386,6 +390,14 @@ impl SpecializedMaterial for StandardMaterial {
                 .push(String::from("STANDARDMATERIAL_NORMAL_MAP"));
         }
         descriptor.primitive.cull_mode = key.cull_mode;
+        if !key.use_storage_buffers {
+            descriptor
+                .fragment
+                .as_mut()
+                .unwrap()
+                .shader_defs
+                .push(String::from("NO_STORAGE_BUFFERS_SUPPORT"));
+        }
         if let Some(label) = &mut descriptor.label {
             *label = format!("pbr_{}", *label).into();
         }