Add marker component for point and spot light shadow primary camera

Author: kfc35

crates/bevy_pbr/src/render/gpu_preprocess.rs

@@ -62,8 +62,8 @@ use bevy_render::{
     renderer::{RenderContext, RenderDevice, RenderQueue, ViewQuery},
     settings::WgpuFeatures,
     view::{
-        ExtractedView, NoIndirectDrawing, RenderVisibilityRanges, RetainedViewEntity, ViewUniform,
-        ViewUniformOffset, ViewUniforms,
+        ExtractedView, NoIndirectDrawing, PointAndSpotLightShadowPrimaryCamera,
+        RenderVisibilityRanges, RetainedViewEntity, ViewUniform, ViewUniformOffset, ViewUniforms,
     },
     GpuResourceAppExt, Render, RenderApp, RenderSystems,
 };
@@ -617,7 +617,13 @@ pub fn early_gpu_preprocess(
         ),
         Without<SkipGpuPreprocess>,
     >,
-    camera_views: Query<&ExtractedView, (With<ExtractedCamera>, Without<SkipGpuPreprocess>)>,
+    point_and_spot_light_shadow_primary_camera: Query<
+        &ExtractedView,
+        (
+            With<ExtractedCamera>,
+            With<PointAndSpotLightShadowPrimaryCamera>,
+        ),
+    >,
     view_query: Query<
         (
             &ExtractedView,
@@ -650,6 +656,8 @@ pub fn early_gpu_preprocess(
     let (shadow_cascade_views, extracted_view, has_non_root_view) = current_view.into_inner();
     let all_views =
         gather_shadow_cascades_for_view(view_entity, shadow_cascade_views, &light_query);
+    let point_and_spot_light_shadow_camera_view =
+        point_and_spot_light_shadow_primary_camera.single();
 
     // Run the compute passes.
     for view_entity in all_views {
@@ -668,16 +676,13 @@ pub fn early_gpu_preprocess(
             extracted_view.world_from_view.translation().to_array()
         } else {
             // PointLight and SpotLight shadow views are handled in this else block.
-            // TODO: We need to better handle this case.
-            // As written, point and spot lights shadow views will just use the first user camera
-            // that is returned by the query.
-            // If there is only one user camera, this is fine, but for multiple user cameras,
-            // only one of them is randomly used for visibility range culling.
-            let camera_view: Option<&ExtractedView> = camera_views.iter().next();
-            if let Some(camera_view) = camera_view {
+            // We could handle this case better if we can specify certain point and spot light shadow
+            // views to different cameras. Right now, it is all centralized to one user specified camera.
+            if let Ok(camera_view) = point_and_spot_light_shadow_camera_view {
                 camera_view.world_from_view.translation().to_array()
             } else {
-                // No camera views to render to.
+                // There is no single designated primary camera to use for vis range culling of the shadows.
+                // Do not render them.
                 continue;
             }
         };

crates/bevy_render/src/camera.rs

@@ -11,8 +11,9 @@ use crate::{
     texture::{GpuImage, ManualTextureViews},
     view::{
         ColorGrading, ExtractedView, ExtractedWindows, Msaa, NoIndirectDrawing,
-        RenderExtractedVisibleEntities, RenderVisibleEntities, RenderVisibleEntitiesClass,
-        RetainedViewEntity, ViewUniformOffset, VisibilityExtractionSystemParam,
+        PointAndSpotLightShadowPrimaryCamera, RenderExtractedVisibleEntities,
+        RenderVisibleEntities, RenderVisibleEntitiesClass, RetainedViewEntity, ViewUniformOffset,
+        VisibilityExtractionSystemParam,
     },
     Extract, ExtractSchedule, Render, RenderApp, RenderSystems,
 };
@@ -492,6 +493,7 @@ pub fn extract_cameras(
                 Option<&MipBias>,
                 Option<&RenderLayers>,
                 Option<&Projection>,
+                Has<PointAndSpotLightShadowPrimaryCamera>,
                 Has<NoIndirectDrawing>,
             ),
         )>,
@@ -517,6 +519,7 @@ pub fn extract_cameras(
         MipBias,
         RenderLayers,
         Projection,
+        PointAndSpotLightShadowPrimaryCamera,
         NoIndirectDrawing,
         ViewUniformOffset,
     );
@@ -538,6 +541,7 @@ pub fn extract_cameras(
             mip_bias,
             render_layers,
             projection,
+            has_pasl_shadow_primary_camera,
             no_indirect_drawing,
         ),
     ) in query.iter()
@@ -682,6 +686,12 @@ pub fn extract_cameras(
                 commands.remove::<Projection>();
             }
 
+            if has_pasl_shadow_primary_camera {
+                commands.insert(PointAndSpotLightShadowPrimaryCamera);
+            } else {
+                commands.remove::<PointAndSpotLightShadowPrimaryCamera>();
+            }
+
             if no_indirect_drawing
                 || !matches!(
                     gpu_preprocessing_support.max_supported_mode,

crates/bevy_render/src/view/visibility/range.rs

@@ -4,6 +4,7 @@
 use super::VisibilityRange;
 use bevy_app::{App, Plugin};
 use bevy_ecs::{
+    component::Component,
     entity::Entity,
     lifecycle::RemovedComponents,
     query::Changed,
@@ -57,6 +58,23 @@ impl Plugin for RenderVisibilityRangePlugin {
     }
 }
 
+/// A marker component for a `Camera` to denote that this entity should be the primary camera
+/// used for GPU Visibility Range Culling on shadows produced by all `PointLight`s and
+/// `SpotLight`s. There should only be one `Camera` with this marker component
+/// at a given moment in the application. This culling will occur if `GpuPreprocessingMode`
+/// is at least `GpuPreprocessingMode::PreprocessingOnly`.
+///
+/// Unlike `DirectionalLight` shadows, `PointLight` shadows and `SpotLight` shadows are
+/// not associated with any camera. They are only rendered once, regardless of the
+/// number of cameras. In order for these shadows to participate in visibility range culling,
+/// the user camera that distances are calculated relative to must be specified. Use this component
+/// to specify that camera.
+///
+/// If this marker component is not placed on a camera, or if there are multiple cameras
+/// with this component, shadows made by `PointLight`s and `SpotLight`s may not render.
+#[derive(Component, Default)]
+pub struct PointAndSpotLightShadowPrimaryCamera;
+
 /// Stores information related to [`VisibilityRange`]s in the render world.
 #[derive(Resource)]
 pub struct RenderVisibilityRanges {

examples/testbed/3d.rs

@@ -122,6 +122,7 @@ mod light {
     use bevy::{
         color::palettes::css::{DEEP_PINK, LIME, RED},
         prelude::*,
+        render::view::PointAndSpotLightShadowPrimaryCamera,
     };
 
     const CURRENT_SCENE: super::Scene = super::Scene::Light;
@@ -203,6 +204,7 @@ mod light {
 
         commands.spawn((
             Camera3d::default(),
+            PointAndSpotLightShadowPrimaryCamera,
             Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
             DespawnOnExit(CURRENT_SCENE),
         ));
@@ -732,6 +734,7 @@ mod render_layers {
     use bevy::{
         camera::{visibility::RenderLayers, Viewport},
         prelude::*,
+        render::view::PointAndSpotLightShadowPrimaryCamera,
         window::PrimaryWindow,
     };
 
@@ -805,7 +808,9 @@ mod render_layers {
                 DespawnOnExit(CURRENT_SCENE),
             ));
             match index {
-                0 => {}
+                0 => {
+                    entity_cmds.insert(PointAndSpotLightShadowPrimaryCamera);
+                }
                 1 => {
                     entity_cmds.insert(RenderLayers::layer(1));
                 }