Texture Atlas rework (#5103)

# Objective

> Old MR: #5072 
> ~~Associated UI MR: #5070~~
> Adresses #1618

Unify sprite management

## Solution

- Remove the `Handle<Image>` field in `TextureAtlas` which is the main
cause for all the boilerplate
- Remove the redundant `TextureAtlasSprite` component
- Renamed `TextureAtlas` asset to `TextureAtlasLayout`
([suggestion](#5103 (comment)))
- Add a `TextureAtlas` component, containing the atlas layout handle and
the section index

The difference between this solution and #5072 is that instead of the
`enum` approach is that we can more easily manipulate texture sheets
without any breaking changes for classic `SpriteBundle`s (@mockersf
[comment](#5072 (comment)))

Also, this approach is more *data oriented* extracting the
`Handle<Image>` and avoiding complex texture atlas manipulations to
retrieve the texture in both applicative and engine code.
With this method, the only difference between a `SpriteBundle` and a
`SpriteSheetBundle` is an **additional** component storing the atlas
handle and the index.

~~This solution can be applied to `bevy_ui` as well (see #5070).~~

EDIT: I also applied this solution to Bevy UI

## Changelog

- (**BREAKING**) Removed `TextureAtlasSprite`
- (**BREAKING**) Renamed `TextureAtlas` to `TextureAtlasLayout`
- (**BREAKING**) `SpriteSheetBundle`:
  - Uses a  `Sprite` instead of a `TextureAtlasSprite` component
- Has a `texture` field containing a `Handle<Image>` like the
`SpriteBundle`
- Has a new `TextureAtlas` component instead of a
`Handle<TextureAtlasLayout>`
- (**BREAKING**) `DynamicTextureAtlasBuilder::add_texture` takes an
additional `&Handle<Image>` parameter
- (**BREAKING**) `TextureAtlasLayout::from_grid` no longer takes a
`Handle<Image>` parameter
- (**BREAKING**) `TextureAtlasBuilder::finish` now returns a
`Result<(TextureAtlasLayout, Handle<Image>), _>`
- `bevy_text`:
  - `GlyphAtlasInfo` stores the texture `Handle<Image>`
  - `FontAtlas` stores the texture `Handle<Image>`
- `bevy_ui`:
- (**BREAKING**) Removed `UiAtlasImage` , the atlas bundle is now
identical to the `ImageBundle` with an additional `TextureAtlas`

## Migration Guide

* Sprites

```diff
fn my_system(
  mut images: ResMut<Assets<Image>>, 
-  mut atlases: ResMut<Assets<TextureAtlas>>, 
+  mut atlases: ResMut<Assets<TextureAtlasLayout>>, 
  asset_server: Res<AssetServer>
) {
    let texture_handle: asset_server.load("my_texture.png");
-   let layout = TextureAtlas::from_grid(texture_handle, Vec2::new(25.0, 25.0), 5, 5, None, None);
+   let layout = TextureAtlasLayout::from_grid(Vec2::new(25.0, 25.0), 5, 5, None, None);
    let layout_handle = atlases.add(layout);
    commands.spawn(SpriteSheetBundle {
-      sprite: TextureAtlasSprite::new(0),
-      texture_atlas: atlas_handle,
+      atlas: TextureAtlas {
+         layout: layout_handle,
+         index: 0
+      },
+      texture: texture_handle,
       ..Default::default()
     });
}
```
* UI


```diff
fn my_system(
  mut images: ResMut<Assets<Image>>, 
-  mut atlases: ResMut<Assets<TextureAtlas>>, 
+  mut atlases: ResMut<Assets<TextureAtlasLayout>>, 
  asset_server: Res<AssetServer>
) {
    let texture_handle: asset_server.load("my_texture.png");
-   let layout = TextureAtlas::from_grid(texture_handle, Vec2::new(25.0, 25.0), 5, 5, None, None);
+   let layout = TextureAtlasLayout::from_grid(Vec2::new(25.0, 25.0), 5, 5, None, None);
    let layout_handle = atlases.add(layout);
    commands.spawn(AtlasImageBundle {
-      texture_atlas_image: UiTextureAtlasImage {
-           index: 0,
-           flip_x: false,
-           flip_y: false,
-       },
-      texture_atlas: atlas_handle,
+      atlas: TextureAtlas {
+         layout: layout_handle,
+         index: 0
+      },
+      image: UiImage {
+           texture: texture_handle,
+           flip_x: false,
+           flip_y: false,
+       },
       ..Default::default()
     });
}
```

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>

crates/bevy_sprite/src/bundle.rs

@@ -1,7 +1,4 @@
-use crate::{
-    texture_atlas::{TextureAtlas, TextureAtlasSprite},
-    ImageScaleMode, Sprite,
-};
+use crate::{texture_atlas::TextureAtlas, ImageScaleMode, Sprite};
 use bevy_asset::Handle;
 use bevy_ecs::bundle::Bundle;
 use bevy_render::{
@@ -32,18 +29,25 @@ pub struct SpriteBundle {
 }
 
 /// A [`Bundle`] of components for drawing a single sprite from a sprite sheet (also referred
-/// to as a `TextureAtlas`).
+/// to as a `TextureAtlas`) or for animated sprites.
+///
+/// Note:
+/// This bundle is identical to [`SpriteBundle`] with an additional [`TextureAtlas`] component.
+///
+/// Check the following examples for usage:
+/// - [`animated sprite sheet example`](https://github.com/bevyengine/bevy/blob/latest/examples/2d/sprite_sheet.rs)
+/// - [`texture atlas example`](https://github.com/bevyengine/bevy/blob/latest/examples/2d/texture_atlas.rs)
 #[derive(Bundle, Clone, Default)]
 pub struct SpriteSheetBundle {
-    /// The specific sprite from the texture atlas to be drawn, defaulting to the sprite at index 0.
-    pub sprite: TextureAtlasSprite,
+    pub sprite: Sprite,
     /// Controls how the image is altered when scaled.
     pub scale_mode: ImageScaleMode,
-    /// A handle to the texture atlas that holds the sprite images
-    pub texture_atlas: Handle<TextureAtlas>,
-    /// Data pertaining to how the sprite is drawn on the screen
     pub transform: Transform,
     pub global_transform: GlobalTransform,
+    /// The sprite sheet base texture
+    pub texture: Handle<Image>,
+    /// The sprite sheet texture atlas, allowing to draw a custom section of `texture`.
+    pub atlas: TextureAtlas,
     /// User indication of whether an entity is visible
     pub visibility: Visibility,
     pub inherited_visibility: InheritedVisibility,

crates/bevy_sprite/src/dynamic_texture_atlas_builder.rs

@@ -1,16 +1,16 @@
-use crate::TextureAtlas;
-use bevy_asset::Assets;
+use crate::TextureAtlasLayout;
+use bevy_asset::{Assets, Handle};
 use bevy_math::{IVec2, Rect, Vec2};
 use bevy_render::{
     render_asset::RenderAssetPersistencePolicy,
     texture::{Image, TextureFormatPixelInfo},
 };
 use guillotiere::{size2, Allocation, AtlasAllocator};
 
-/// Helper utility to update [`TextureAtlas`] on the fly.
+/// Helper utility to update [`TextureAtlasLayout`] on the fly.
 ///
 /// Helpful in cases when texture is created procedurally,
-/// e.g: in a font glyph [`TextureAtlas`], only add the [`Image`] texture for letters to be rendered.
+/// e.g: in a font glyph [`TextureAtlasLayout`], only add the [`Image`] texture for letters to be rendered.
 pub struct DynamicTextureAtlasBuilder {
     atlas_allocator: AtlasAllocator,
     padding: i32,
@@ -30,22 +30,30 @@ impl DynamicTextureAtlasBuilder {
         }
     }
 
-    /// Add a new texture to [`TextureAtlas`].
-    /// It is user's responsibility to pass in the correct [`TextureAtlas`],
-    /// and that [`TextureAtlas::texture`] has [`Image::cpu_persistent_access`]
+    /// Add a new texture to `atlas_layout`
+    /// It is the user's responsibility to pass in the correct [`TextureAtlasLayout`]
+    /// and that `atlas_texture_handle` has [`Image::cpu_persistent_access`]
     /// set to [`RenderAssetPersistencePolicy::Keep`]
+    ///
+    /// # Arguments
+    ///
+    /// * `altas_layout` - The atlas to add the texture to
+    /// * `textures` - The texture assets container
+    /// * `texture` - The new texture to add to the atlas
+    /// * `atlas_texture_handle` - The atlas texture to edit
     pub fn add_texture(
         &mut self,
-        texture_atlas: &mut TextureAtlas,
+        atlas_layout: &mut TextureAtlasLayout,
         textures: &mut Assets<Image>,
         texture: &Image,
+        atlas_texture_handle: &Handle<Image>,
     ) -> Option<usize> {
         let allocation = self.atlas_allocator.allocate(size2(
             texture.width() as i32 + self.padding,
             texture.height() as i32 + self.padding,
         ));
         if let Some(allocation) = allocation {
-            let atlas_texture = textures.get_mut(&texture_atlas.texture).unwrap();
+            let atlas_texture = textures.get_mut(atlas_texture_handle).unwrap();
             assert_eq!(
                 atlas_texture.cpu_persistent_access,
                 RenderAssetPersistencePolicy::Keep
@@ -54,7 +62,7 @@ impl DynamicTextureAtlasBuilder {
             self.place_texture(atlas_texture, allocation, texture);
             let mut rect: Rect = to_rect(allocation.rectangle);
             rect.max -= self.padding as f32;
-            Some(texture_atlas.add_texture(rect))
+            Some(atlas_layout.add_texture(rect))
         } else {
             None
         }

crates/bevy_sprite/src/lib.rs

@@ -15,7 +15,7 @@ pub mod prelude {
     pub use crate::{
         bundle::{SpriteBundle, SpriteSheetBundle},
         sprite::{ImageScaleMode, Sprite},
-        texture_atlas::{TextureAtlas, TextureAtlasSprite},
+        texture_atlas::{TextureAtlas, TextureAtlasLayout},
         texture_slice::{BorderRect, SliceScaleMode, TextureSlicer},
         ColorMaterial, ColorMesh2dBundle, TextureAtlasBuilder,
     };
@@ -65,13 +65,13 @@ impl Plugin for SpritePlugin {
             "render/sprite.wgsl",
             Shader::from_wgsl
         );
-        app.init_asset::<TextureAtlas>()
-            .register_asset_reflect::<TextureAtlas>()
+        app.init_asset::<TextureAtlasLayout>()
+            .register_asset_reflect::<TextureAtlasLayout>()
             .register_type::<Sprite>()
             .register_type::<ImageScaleMode>()
             .register_type::<TextureSlicer>()
-            .register_type::<TextureAtlasSprite>()
             .register_type::<Anchor>()
+            .register_type::<TextureAtlas>()
             .register_type::<Mesh2dHandle>()
             .add_plugins((Mesh2dRenderPlugin, ColorMaterialPlugin))
             .add_systems(
@@ -131,19 +131,15 @@ pub fn calculate_bounds_2d(
     mut commands: Commands,
     meshes: Res<Assets<Mesh>>,
     images: Res<Assets<Image>>,
-    atlases: Res<Assets<TextureAtlas>>,
+    atlases: Res<Assets<TextureAtlasLayout>>,
     meshes_without_aabb: Query<(Entity, &Mesh2dHandle), (Without<Aabb>, Without<NoFrustumCulling>)>,
     sprites_to_recalculate_aabb: Query<
-        (Entity, &Sprite, &Handle<Image>),
+        (Entity, &Sprite, &Handle<Image>, Option<&TextureAtlas>),
         (
             Or<(Without<Aabb>, Changed<Sprite>)>,
             Without<NoFrustumCulling>,
         ),
     >,
-    atlases_without_aabb: Query<
-        (Entity, &TextureAtlasSprite, &Handle<TextureAtlas>),
-        (Without<Aabb>, Without<NoFrustumCulling>),
-    >,
 ) {
     for (entity, mesh_handle) in &meshes_without_aabb {
         if let Some(mesh) = meshes.get(&mesh_handle.0) {
@@ -152,27 +148,15 @@ pub fn calculate_bounds_2d(
             }
         }
     }
-    for (entity, sprite, texture_handle) in &sprites_to_recalculate_aabb {
-        if let Some(size) = sprite
-            .custom_size
-            .or_else(|| images.get(texture_handle).map(|image| image.size_f32()))
-        {
-            let aabb = Aabb {
-                center: (-sprite.anchor.as_vec() * size).extend(0.0).into(),
-                half_extents: (0.5 * size).extend(0.0).into(),
-            };
-            commands.entity(entity).try_insert(aabb);
-        }
-    }
-    for (entity, atlas_sprite, atlas_handle) in &atlases_without_aabb {
-        if let Some(size) = atlas_sprite.custom_size.or_else(|| {
-            atlases
-                .get(atlas_handle)
-                .and_then(|atlas| atlas.textures.get(atlas_sprite.index))
-                .map(|rect| (rect.min - rect.max).abs())
+    for (entity, sprite, texture_handle, atlas) in &sprites_to_recalculate_aabb {
+        if let Some(size) = sprite.custom_size.or_else(|| match atlas {
+            // We default to the texture size for regular sprites
+            None => images.get(texture_handle).map(|image| image.size_f32()),
+            // We default to the drawn rect for atlas sprites
+            Some(atlas) => atlas.texture_rect(&atlases).map(|rect| rect.size()),
         }) {
             let aabb = Aabb {
-                center: (-atlas_sprite.anchor.as_vec() * size).extend(0.0).into(),
+                center: (-sprite.anchor.as_vec() * size).extend(0.0).into(),
                 half_extents: (0.5 * size).extend(0.0).into(),
             };
             commands.entity(entity).try_insert(aabb);
@@ -199,7 +183,7 @@ mod test {
         app.insert_resource(image_assets);
         let mesh_assets = Assets::<Mesh>::default();
         app.insert_resource(mesh_assets);
-        let texture_atlas_assets = Assets::<TextureAtlas>::default();
+        let texture_atlas_assets = Assets::<TextureAtlasLayout>::default();
         app.insert_resource(texture_atlas_assets);
 
         // Add system
@@ -237,7 +221,7 @@ mod test {
         app.insert_resource(image_assets);
         let mesh_assets = Assets::<Mesh>::default();
         app.insert_resource(mesh_assets);
-        let texture_atlas_assets = Assets::<TextureAtlas>::default();
+        let texture_atlas_assets = Assets::<TextureAtlasLayout>::default();
         app.insert_resource(texture_atlas_assets);
 
         // Add system

crates/bevy_sprite/src/render/mod.rs

@@ -1,7 +1,7 @@
 use std::ops::Range;
 
 use crate::{
-    texture_atlas::{TextureAtlas, TextureAtlasSprite},
+    texture_atlas::{TextureAtlas, TextureAtlasLayout},
     ComputedTextureSlices, Sprite, SPRITE_SHADER_HANDLE,
 };
 use bevy_asset::{AssetEvent, AssetId, Assets, Handle};
@@ -335,47 +335,40 @@ pub fn extract_sprite_events(
 pub fn extract_sprites(
     mut commands: Commands,
     mut extracted_sprites: ResMut<ExtractedSprites>,
-    texture_atlases: Extract<Res<Assets<TextureAtlas>>>,
+    texture_atlases: Extract<Res<Assets<TextureAtlasLayout>>>,
     sprite_query: Extract<
         Query<(
             Entity,
             &ViewVisibility,
             &Sprite,
             &GlobalTransform,
             &Handle<Image>,
+            Option<&TextureAtlas>,
             Option<&ComputedTextureSlices>,
         )>,
     >,
-    atlas_query: Extract<
-        Query<(
-            Entity,
-            &ViewVisibility,
-            &TextureAtlasSprite,
-            &GlobalTransform,
-            &Handle<TextureAtlas>,
-        )>,
-    >,
 ) {
     extracted_sprites.sprites.clear();
-
-    for (entity, view_visibility, sprite, transform, handle, slices) in sprite_query.iter() {
+    for (entity, view_visibility, sprite, transform, handle, sheet, slices) in sprite_query.iter() {
         if !view_visibility.get() {
             continue;
         }
+
         if let Some(slices) = slices {
             extracted_sprites.sprites.extend(
                 slices
                     .extract_sprites(transform, entity, sprite, handle)
                     .map(|e| (commands.spawn_empty().id(), e)),
             );
         } else {
+            let rect = sheet.and_then(|s| s.texture_rect(&texture_atlases));
             // PERF: we don't check in this function that the `Image` asset is ready, since it should be in most cases and hashing the handle is expensive
             extracted_sprites.sprites.insert(
                 entity,
                 ExtractedSprite {
                     color: sprite.color,
                     transform: *transform,
-                    rect: sprite.rect,
+                    rect,
                     // Pass the custom size
                     custom_size: sprite.custom_size,
                     flip_x: sprite.flip_x,
@@ -387,43 +380,6 @@ pub fn extract_sprites(
             );
         }
     }
-    for (entity, view_visibility, atlas_sprite, transform, texture_atlas_handle) in
-        atlas_query.iter()
-    {
-        if !view_visibility.get() {
-            continue;
-        }
-        if let Some(texture_atlas) = texture_atlases.get(texture_atlas_handle) {
-            let rect = Some(
-                *texture_atlas
-                    .textures
-                    .get(atlas_sprite.index)
-                    .unwrap_or_else(|| {
-                        panic!(
-                            "Sprite index {:?} does not exist for texture atlas handle {:?}.",
-                            atlas_sprite.index,
-                            texture_atlas_handle.id(),
-                        )
-                    }),
-            );
-            extracted_sprites.sprites.insert(
-                entity,
-                ExtractedSprite {
-                    color: atlas_sprite.color,
-                    transform: *transform,
-                    // Select the area in the texture atlas
-                    rect,
-                    // Pass the custom size
-                    custom_size: atlas_sprite.custom_size,
-                    flip_x: atlas_sprite.flip_x,
-                    flip_y: atlas_sprite.flip_y,
-                    image_handle_id: texture_atlas.texture.id(),
-                    anchor: atlas_sprite.anchor.as_vec(),
-                    original_entity: None,
-                },
-            );
-        }
-    }
 }
 
 #[repr(C)]