Squash pr bevyengine#4402

Setup infrastructure for render app owns extract

Commit 'progress'

Finish API

Cleverly avoid needing the param to be 'static

This same trick can't work for `StaticSystemParam` fwiw
This is because `StaticSystemParam`'s item needs to exactly
reference the original param, whereas this just stores it

Migrate to the new pattern

Remove `spawn_and_forget`

It's unused, and was only ever needed for the weird extract logic

Fix clippy errors

Remove the trick because it's actually stupid

Add some docs

Fixup docs

crates/bevy_core_pipeline/src/lib.rs

@@ -34,7 +34,7 @@ use bevy_render::{
     renderer::RenderDevice,
     texture::TextureCache,
     view::{ExtractedView, Msaa, ViewDepthTexture},
-    RenderApp, RenderStage, RenderWorld,
+    Extract, RenderApp, RenderStage,
 };
 
 /// When used as a resource, sets the color that is used to clear the screen between frames.
@@ -348,34 +348,36 @@ impl CachedRenderPipelinePhaseItem for Transparent3d {
 }
 
 pub fn extract_clear_color(
-    clear_color: Res<ClearColor>,
-    clear_colors: Res<RenderTargetClearColors>,
-    mut render_world: ResMut<RenderWorld>,
+    mut clear_color: Extract<Res<ClearColor>>,
+    mut clear_colors: Extract<Res<RenderTargetClearColors>>,
+    mut commands: Commands,
 ) {
+    let clear_color = clear_color.value();
     // If the clear color has changed
     if clear_color.is_changed() {
         // Update the clear color resource in the render world
-        render_world.insert_resource(clear_color.clone());
+        commands.insert_resource(clear_color.clone());
     }
 
+    let clear_colors = clear_colors.value();
     // If the clear color has changed
     if clear_colors.is_changed() {
         // Update the clear color resource in the render world
-        render_world.insert_resource(clear_colors.clone());
+        commands.insert_resource(clear_colors.clone());
     }
 }
 
 pub fn extract_core_pipeline_camera_phases(
     mut commands: Commands,
-    active_2d: Res<ActiveCamera<Camera2d>>,
-    active_3d: Res<ActiveCamera<Camera3d>>,
+    mut active_2d: Extract<Res<ActiveCamera<Camera2d>>>,
+    mut active_3d: Extract<Res<ActiveCamera<Camera3d>>>,
 ) {
-    if let Some(entity) = active_2d.get() {
+    if let Some(entity) = active_2d.value().get() {
         commands
             .get_or_spawn(entity)
             .insert(RenderPhase::<Transparent2d>::default());
     }
-    if let Some(entity) = active_3d.get() {
+    if let Some(entity) = active_3d.value().get() {
         commands.get_or_spawn(entity).insert_bundle((
             RenderPhase::<Opaque3d>::default(),
             RenderPhase::<AlphaMask3d>::default(),

crates/bevy_ecs/src/event.rs

@@ -1,6 +1,6 @@
 //! Event handling types.
 
-use crate::system::{Local, Res, ResMut, SystemParam};
+use crate::system::{Local, ReadOnlySystemParamFetch, Res, ResMut, SystemParam};
 use crate::{self as bevy_ecs, system::Resource};
 use bevy_utils::tracing::trace;
 use std::{
@@ -164,6 +164,8 @@ pub struct EventReader<'w, 's, T: Resource> {
     events: Res<'w, Events<T>>,
 }
 
+unsafe impl<A, T: Resource> ReadOnlySystemParamFetch for EventReaderState<A, T> {}
+
 /// Sends events of type `T`.
 #[derive(SystemParam)]
 pub struct EventWriter<'w, 's, T: Resource> {

crates/bevy_ecs/src/system/commands/mod.rs

@@ -104,12 +104,6 @@ impl<'w, 's> Commands<'w, 's> {
         }
     }
 
-    /// Spawns a [`Bundle`] without pre-allocating an [`Entity`]. The [`Entity`] will be allocated
-    /// when this [`Command`] is applied.
-    pub fn spawn_and_forget(&mut self, bundle: impl Bundle) {
-        self.queue.push(Spawn { bundle });
-    }
-
     /// Creates a new entity with the components contained in `bundle`.
     ///
     /// This returns an [`EntityCommands`] builder, which enables inserting more components and

crates/bevy_pbr/src/render/light.rs

@@ -28,6 +28,7 @@ use bevy_render::{
     view::{
         ExtractedView, ViewUniform, ViewUniformOffset, ViewUniforms, Visibility, VisibleEntities,
     },
+    Extract,
 };
 use bevy_transform::components::GlobalTransform;
 use bevy_utils::{
@@ -331,8 +332,11 @@ pub struct ExtractedClustersPointLights {
     data: Vec<VisiblePointLights>,
 }
 
-pub fn extract_clusters(mut commands: Commands, views: Query<(Entity, &Clusters), With<Camera>>) {
-    for (entity, clusters) in views.iter() {
+pub fn extract_clusters(
+    mut commands: Commands,
+    mut views: Extract<Query<(Entity, &Clusters), With<Camera>>>,
+) {
+    for (entity, clusters) in views.value().iter() {
         commands.get_or_spawn(entity).insert_bundle((
             ExtractedClustersPointLights {
                 data: clusters.lights.clone(),
@@ -348,20 +352,25 @@ pub fn extract_clusters(mut commands: Commands, views: Query<(Entity, &Clusters)
 
 pub fn extract_lights(
     mut commands: Commands,
-    ambient_light: Res<AmbientLight>,
-    point_light_shadow_map: Res<PointLightShadowMap>,
-    directional_light_shadow_map: Res<DirectionalLightShadowMap>,
-    global_point_lights: Res<GlobalVisiblePointLights>,
+    mut ambient_light: Extract<Res<AmbientLight>>,
+    mut point_light_shadow_map: Extract<Res<PointLightShadowMap>>,
+    mut directional_light_shadow_map: Extract<Res<DirectionalLightShadowMap>>,
+    mut global_point_lights: Extract<Res<GlobalVisiblePointLights>>,
     // visible_point_lights: Query<&VisiblePointLights>,
-    mut point_lights: Query<(&PointLight, &mut CubemapVisibleEntities, &GlobalTransform)>,
-    mut directional_lights: Query<(
-        Entity,
-        &DirectionalLight,
-        &mut VisibleEntities,
-        &GlobalTransform,
-        &Visibility,
-    )>,
+    mut point_lights: Extract<Query<(&PointLight, &CubemapVisibleEntities, &GlobalTransform)>>,
+    mut directional_lights: Extract<
+        Query<(
+            Entity,
+            &DirectionalLight,
+            &VisibleEntities,
+            &GlobalTransform,
+            &Visibility,
+        )>,
+    >,
 ) {
+    let ambient_light = ambient_light.value();
+    let point_light_shadow_map = point_light_shadow_map.value();
+    let directional_light_shadow_map = directional_light_shadow_map.value();
     commands.insert_resource(ExtractedAmbientLight {
         color: ambient_light.color,
         brightness: ambient_light.brightness,
@@ -379,11 +388,15 @@ pub fn extract_lights(
     // https://catlikecoding.com/unity/tutorials/custom-srp/point-and-spot-shadows/
     let point_light_texel_size = 2.0 / point_light_shadow_map.size as f32;
 
-    for entity in global_point_lights.iter().copied() {
-        if let Ok((point_light, cubemap_visible_entities, transform)) = point_lights.get_mut(entity)
-        {
-            let render_cubemap_visible_entities =
-                std::mem::take(cubemap_visible_entities.into_inner());
+    let point_lights = point_lights.value();
+    for entity in global_point_lights.value().iter().copied() {
+        if let Ok((point_light, cubemap_visible_entities, transform)) = point_lights.get(entity) {
+            // PERF: Ideally, this would avoid creating new allocations each frame.
+            // The nicest way to do that would be to get last frame's render_cubemap_visible_entities,
+            // and clone into that buffer.
+            // TODO: Evaluate whether moving the buffers into a resource at the end of frame
+            // is more performant.
+            let render_cubemap_visible_entities = cubemap_visible_entities.clone();
             commands.get_or_spawn(entity).insert_bundle((
                 ExtractedPointLight {
                     color: point_light.color,
@@ -407,7 +420,7 @@ pub fn extract_lights(
     }
 
     for (entity, directional_light, visible_entities, transform, visibility) in
-        directional_lights.iter_mut()
+        directional_lights.value().iter()
     {
         if !visibility.is_visible {
             continue;
@@ -425,7 +438,8 @@ pub fn extract_lights(
             );
         let directional_light_texel_size =
             largest_dimension / directional_light_shadow_map.size as f32;
-        let render_visible_entities = std::mem::take(visible_entities.into_inner());
+        // See above
+        let render_visible_entities = visible_entities.clone();
         commands.get_or_spawn(entity).insert_bundle((
             ExtractedDirectionalLight {
                 color: directional_light.color,

crates/bevy_pbr/src/render/mesh.rs

@@ -22,7 +22,7 @@ use bevy_render::{
     renderer::{RenderDevice, RenderQueue},
     texture::{BevyDefault, GpuImage, Image, TextureFormatPixelInfo},
     view::{ComputedVisibility, ViewUniform, ViewUniformOffset, ViewUniforms},
-    RenderApp, RenderStage,
+    Extract, RenderApp, RenderStage,
 };
 use bevy_transform::components::GlobalTransform;
 use smallvec::SmallVec;
@@ -97,29 +97,35 @@ pub fn extract_meshes(
     mut commands: Commands,
     mut previous_caster_len: Local<usize>,
     mut previous_not_caster_len: Local<usize>,
-    caster_query: Query<
-        (
-            Entity,
-            &ComputedVisibility,
-            &GlobalTransform,
-            &Handle<Mesh>,
-            Option<&NotShadowReceiver>,
-        ),
-        Without<NotShadowCaster>,
+    mut caster_query: Extract<
+        Query<
+            (
+                Entity,
+                &ComputedVisibility,
+                &GlobalTransform,
+                &Handle<Mesh>,
+                Option<&NotShadowReceiver>,
+            ),
+            Without<NotShadowCaster>,
+        >,
     >,
-    not_caster_query: Query<
-        (
-            Entity,
-            &ComputedVisibility,
-            &GlobalTransform,
-            &Handle<Mesh>,
-            Option<&NotShadowReceiver>,
-        ),
-        With<NotShadowCaster>,
+    mut not_caster_query: Extract<
+        Query<
+            (
+                Entity,
+                &ComputedVisibility,
+                &GlobalTransform,
+                &Handle<Mesh>,
+                Option<&NotShadowReceiver>,
+            ),
+            With<NotShadowCaster>,
+        >,
     >,
 ) {
     let mut caster_values = Vec::with_capacity(*previous_caster_len);
-    for (entity, computed_visibility, transform, handle, not_receiver) in caster_query.iter() {
+    for (entity, computed_visibility, transform, handle, not_receiver) in
+        caster_query.value().iter()
+    {
         if !computed_visibility.is_visible {
             continue;
         }
@@ -144,7 +150,9 @@ pub fn extract_meshes(
     commands.insert_or_spawn_batch(caster_values);
 
     let mut not_caster_values = Vec::with_capacity(*previous_not_caster_len);
-    for (entity, computed_visibility, transform, mesh, not_receiver) in not_caster_query.iter() {
+    for (entity, computed_visibility, transform, mesh, not_receiver) in
+        not_caster_query.value().iter()
+    {
         if !computed_visibility.is_visible {
             continue;
         }
@@ -216,18 +224,20 @@ impl SkinnedMeshJoints {
 }
 
 pub fn extract_skinned_meshes(
-    query: Query<(Entity, &ComputedVisibility, &SkinnedMesh)>,
-    inverse_bindposes: Res<Assets<SkinnedMeshInverseBindposes>>,
-    joint_query: Query<&GlobalTransform>,
+    mut query: Extract<Query<(Entity, &ComputedVisibility, &SkinnedMesh)>>,
+    mut inverse_bindposes: Extract<Res<Assets<SkinnedMeshInverseBindposes>>>,
+    mut joint_query: Extract<Query<&GlobalTransform>>,
     mut commands: Commands,
     mut previous_len: Local<usize>,
     mut previous_joint_len: Local<usize>,
 ) {
+    let inverse_bindposes = inverse_bindposes.value();
     let mut values = Vec::with_capacity(*previous_len);
     let mut joints = Vec::with_capacity(*previous_joint_len);
     let mut last_start = 0;
 
-    for (entity, computed_visibility, skin) in query.iter() {
+    let joint_query = joint_query.value();
+    for (entity, computed_visibility, skin) in query.value().iter() {
         if !computed_visibility.is_visible {
             continue;
         }

crates/bevy_pbr/src/wireframe.rs

@@ -5,6 +5,7 @@ use bevy_asset::{load_internal_asset, Handle, HandleUntyped};
 use bevy_core_pipeline::Opaque3d;
 use bevy_ecs::{prelude::*, reflect::ReflectComponent};
 use bevy_reflect::{Reflect, TypeUuid};
+use bevy_render::Extract;
 use bevy_render::{
     mesh::{Mesh, MeshVertexBufferLayout},
     render_asset::RenderAssets,
@@ -47,14 +48,18 @@ impl Plugin for WireframePlugin {
     }
 }
 
-fn extract_wireframe_config(mut commands: Commands, wireframe_config: Res<WireframeConfig>) {
+fn extract_wireframe_config(
+    mut commands: Commands,
+    mut wireframe_config: Extract<Res<WireframeConfig>>,
+) {
+    let wireframe_config = wireframe_config.value();
     if wireframe_config.is_added() || wireframe_config.is_changed() {
         commands.insert_resource(wireframe_config.into_inner().clone());
     }
 }
 
-fn extract_wireframes(mut commands: Commands, query: Query<Entity, With<Wireframe>>) {
-    for entity in query.iter() {
+fn extract_wireframes(mut commands: Commands, mut query: Extract<Query<Entity, With<Wireframe>>>) {
+    for entity in query.value().iter() {
         commands.get_or_spawn(entity).insert(Wireframe);
     }
 }

crates/bevy_render/src/camera/camera.rs

@@ -6,7 +6,7 @@ use crate::{
     render_asset::RenderAssets,
     render_resource::TextureView,
     view::{ExtractedView, ExtractedWindows, VisibleEntities},
-    RenderApp, RenderStage,
+    Extract, RenderApp, RenderStage,
 };
 use bevy_app::{App, CoreStage, Plugin, StartupStage};
 use bevy_asset::{AssetEvent, Assets, Handle};
@@ -288,18 +288,22 @@ pub struct ExtractedCamera {
 
 pub fn extract_cameras<M: Component + Default>(
     mut commands: Commands,
-    windows: Res<Windows>,
-    images: Res<Assets<Image>>,
-    active_camera: Res<ActiveCamera<M>>,
-    query: Query<(&Camera, &GlobalTransform, &VisibleEntities), With<M>>,
+    mut windows: Extract<Res<Windows>>,
+    mut images: Extract<Res<Assets<Image>>>,
+    mut active_camera: Extract<Res<ActiveCamera<M>>>,
+    mut query: Extract<Query<(&Camera, &GlobalTransform, &VisibleEntities), With<M>>>,
 ) {
+    let active_camera = active_camera.value();
     if let Some(entity) = active_camera.get() {
-        if let Ok((camera, transform, visible_entities)) = query.get(entity) {
-            if let Some(size) = camera.target.get_physical_size(&windows, &images) {
+        if let Ok((camera, transform, visible_entities)) = query.value().get(entity) {
+            if let Some(size) = camera
+                .target
+                .get_physical_size(&windows.value(), &images.value())
+            {
                 commands.get_or_spawn(entity).insert_bundle((
                     ExtractedCamera {
                         target: camera.target.clone(),
-                        physical_size: camera.target.get_physical_size(&windows, &images),
+                        physical_size: Some(size),
                     },
                     ExtractedView {
                         projection: camera.projection_matrix,