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Refactor the render instance logic in bevyengine#9903 so that it's ea…
…sier for other components to adopt. (bevyengine#10002) # Objective Currently, the only way for custom components that participate in rendering to opt into the higher-performance extraction method in bevyengine#9903 is to implement the `RenderInstances` data structure and the extraction logic manually. This is inconvenient compared to the `ExtractComponent` API. ## Solution This commit creates a new `RenderInstance` trait that mirrors the existing `ExtractComponent` method but uses the higher-performance approach that bevyengine#9903 uses. Additionally, `RenderInstance` is more flexible than `ExtractComponent`, because it can extract multiple components at once. This makes high-performance rendering components essentially as easy to write as the existing ones based on component extraction. --- ## Changelog ### Added A new `RenderInstance` trait is available mirroring `ExtractComponent`, but using a higher-performance method to extract one or more components to the render world. If you have custom components that rendering takes into account, you may consider migration from `ExtractComponent` to `RenderInstance` for higher performance.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,153 @@ | ||
| //! Convenience logic for turning components from the main world into render | ||
| //! instances in the render world. | ||
| //! | ||
| //! This is essentially the same as the `extract_component` module, but | ||
| //! higher-performance because it avoids the ECS overhead. | ||
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| use std::marker::PhantomData; | ||
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| use bevy_app::{App, Plugin}; | ||
| use bevy_asset::{Asset, AssetId, Handle}; | ||
| use bevy_derive::{Deref, DerefMut}; | ||
| use bevy_ecs::{ | ||
| prelude::Entity, | ||
| query::{QueryItem, ReadOnlyWorldQuery, WorldQuery}, | ||
| system::{lifetimeless::Read, Query, ResMut, Resource}, | ||
| }; | ||
| use bevy_utils::EntityHashMap; | ||
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| use crate::{prelude::ViewVisibility, Extract, ExtractSchedule, RenderApp}; | ||
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| /// Describes how to extract data needed for rendering from a component or | ||
| /// components. | ||
| /// | ||
| /// Before rendering, any applicable components will be transferred from the | ||
| /// main world to the render world in the [`ExtractSchedule`] step. | ||
| /// | ||
| /// This is essentially the same as | ||
| /// [`ExtractComponent`](crate::extract_component::ExtractComponent), but | ||
| /// higher-performance because it avoids the ECS overhead. | ||
| pub trait RenderInstance: Send + Sync + Sized + 'static { | ||
| /// ECS [`WorldQuery`] to fetch the components to extract. | ||
| type Query: WorldQuery + ReadOnlyWorldQuery; | ||
| /// Filters the entities with additional constraints. | ||
| type Filter: WorldQuery + ReadOnlyWorldQuery; | ||
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| /// Defines how the component is transferred into the "render world". | ||
| fn extract_to_render_instance(item: QueryItem<'_, Self::Query>) -> Option<Self>; | ||
| } | ||
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| /// This plugin extracts one or more components into the "render world" as | ||
| /// render instances. | ||
| /// | ||
| /// Therefore it sets up the [`ExtractSchedule`] step for the specified | ||
| /// [`RenderInstances`]. | ||
| #[derive(Default)] | ||
| pub struct RenderInstancePlugin<RI> | ||
| where | ||
| RI: RenderInstance, | ||
| { | ||
| only_extract_visible: bool, | ||
| marker: PhantomData<fn() -> RI>, | ||
| } | ||
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| /// Stores all render instances of a type in the render world. | ||
| #[derive(Resource, Deref, DerefMut)] | ||
| pub struct RenderInstances<RI>(EntityHashMap<Entity, RI>) | ||
| where | ||
| RI: RenderInstance; | ||
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| impl<RI> Default for RenderInstances<RI> | ||
| where | ||
| RI: RenderInstance, | ||
| { | ||
| fn default() -> Self { | ||
| Self(Default::default()) | ||
| } | ||
| } | ||
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| impl<RI> RenderInstancePlugin<RI> | ||
| where | ||
| RI: RenderInstance, | ||
| { | ||
| /// Creates a new [`RenderInstancePlugin`] that unconditionally extracts to | ||
| /// the render world, whether the entity is visible or not. | ||
| pub fn new() -> Self { | ||
| Self { | ||
| only_extract_visible: false, | ||
| marker: PhantomData, | ||
| } | ||
| } | ||
| } | ||
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| impl<RI> RenderInstancePlugin<RI> | ||
| where | ||
| RI: RenderInstance, | ||
| { | ||
| /// Creates a new [`RenderInstancePlugin`] that extracts to the render world | ||
| /// if and only if the entity it's attached to is visible. | ||
| pub fn extract_visible() -> Self { | ||
| Self { | ||
| only_extract_visible: true, | ||
| marker: PhantomData, | ||
| } | ||
| } | ||
| } | ||
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| impl<RI> Plugin for RenderInstancePlugin<RI> | ||
| where | ||
| RI: RenderInstance, | ||
| { | ||
| fn build(&self, app: &mut App) { | ||
| if let Ok(render_app) = app.get_sub_app_mut(RenderApp) { | ||
| render_app.init_resource::<RenderInstances<RI>>(); | ||
| if self.only_extract_visible { | ||
| render_app.add_systems(ExtractSchedule, extract_visible_to_render_instances::<RI>); | ||
| } else { | ||
| render_app.add_systems(ExtractSchedule, extract_to_render_instances::<RI>); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| fn extract_to_render_instances<RI>( | ||
| mut instances: ResMut<RenderInstances<RI>>, | ||
| query: Extract<Query<(Entity, RI::Query), RI::Filter>>, | ||
| ) where | ||
| RI: RenderInstance, | ||
| { | ||
| instances.clear(); | ||
| for (entity, other) in &query { | ||
| if let Some(render_instance) = RI::extract_to_render_instance(other) { | ||
| instances.insert(entity, render_instance); | ||
| } | ||
| } | ||
| } | ||
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| fn extract_visible_to_render_instances<RI>( | ||
| mut instances: ResMut<RenderInstances<RI>>, | ||
| query: Extract<Query<(Entity, &ViewVisibility, RI::Query), RI::Filter>>, | ||
| ) where | ||
| RI: RenderInstance, | ||
| { | ||
| instances.clear(); | ||
| for (entity, view_visibility, other) in &query { | ||
| if view_visibility.get() { | ||
| if let Some(render_instance) = RI::extract_to_render_instance(other) { | ||
| instances.insert(entity, render_instance); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| impl<A> RenderInstance for AssetId<A> | ||
| where | ||
| A: Asset, | ||
| { | ||
| type Query = Read<Handle<A>>; | ||
| type Filter = (); | ||
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| fn extract_to_render_instance(item: QueryItem<'_, Self::Query>) -> Option<Self> { | ||
| Some(item.id()) | ||
| } | ||
| } |