Fix Anchor component inconsistancies (#18393)

## Objective

Fix the misleading 2d anchor API where `Anchor` is a component and
required by `Text2d` but is stored on a field for sprites.

Fixes #18367

## Solution

Remove the `anchor` field from `Sprite` and require `Anchor` instead.

## Migration Guide

The `anchor` field has been removed from `Sprite`. Instead the `Anchor`
component is now a required component on `Sprite`.

crates/bevy_sprite/src/lib.rs

@@ -169,9 +169,9 @@ pub fn calculate_bounds_2d(
     atlases: Res<Assets<TextureAtlasLayout>>,
     meshes_without_aabb: Query<(Entity, &Mesh2d), (Without<Aabb>, Without<NoFrustumCulling>)>,
     sprites_to_recalculate_aabb: Query<
-        (Entity, &Sprite),
+        (Entity, &Sprite, &Anchor),
         (
-            Or<(Without<Aabb>, Changed<Sprite>)>,
+            Or<(Without<Aabb>, Changed<Sprite>, Changed<Anchor>)>,
             Without<NoFrustumCulling>,
         ),
     >,
@@ -183,7 +183,7 @@ pub fn calculate_bounds_2d(
             }
         }
     }
-    for (entity, sprite) in &sprites_to_recalculate_aabb {
+    for (entity, sprite, anchor) in &sprites_to_recalculate_aabb {
         if let Some(size) = sprite
             .custom_size
             .or_else(|| sprite.rect.map(|rect| rect.size()))
@@ -197,7 +197,7 @@ pub fn calculate_bounds_2d(
             })
         {
             let aabb = Aabb {
-                center: (-sprite.anchor.as_vec() * size).extend(0.0).into(),
+                center: (-anchor.as_vec() * size).extend(0.0).into(),
                 half_extents: (0.5 * size).extend(0.0).into(),
             };
             commands.entity(entity).try_insert(aabb);
@@ -334,12 +334,14 @@ mod test {
         // Add entities
         let entity = app
             .world_mut()
-            .spawn(Sprite {
+            .spawn((
-                rect: Some(Rect::new(0., 0., 0.5, 1.)),
+                Sprite {
-                anchor: Anchor::TOP_RIGHT,
+                    rect: Some(Rect::new(0., 0., 0.5, 1.)),
-                image: image_handle,
+                    image: image_handle,
-                ..default()
+                    ..default()
-            })
+                },
+                Anchor::TOP_RIGHT,
+            ))
             .id();
 
         // Create AABB

crates/bevy_sprite/src/picking_backend.rs

@@ -10,7 +10,7 @@
 //! - The `position` reported in `HitData` in in world space, and the `normal` is a normalized
 //!   vector provided by the target's `GlobalTransform::back()`.
 
-use crate::Sprite;
+use crate::{Anchor, Sprite};
 use bevy_app::prelude::*;
 use bevy_asset::prelude::*;
 use bevy_color::Alpha;
@@ -100,6 +100,7 @@ fn sprite_picking(
         Entity,
         &Sprite,
         &GlobalTransform,
+        &Anchor,
         &Pickable,
         &ViewVisibility,
     )>,
@@ -107,9 +108,9 @@ fn sprite_picking(
 ) {
     let mut sorted_sprites: Vec<_> = sprite_query
         .iter()
-        .filter_map(|(entity, sprite, transform, pickable, vis)| {
+        .filter_map(|(entity, sprite, transform, anchor, pickable, vis)| {
             if !transform.affine().is_nan() && vis.get() {
-                Some((entity, sprite, transform, pickable))
+                Some((entity, sprite, transform, anchor, pickable))
             } else {
                 None
             }
@@ -117,7 +118,7 @@ fn sprite_picking(
         .collect();
 
     // radsort is a stable radix sort that performed better than `slice::sort_by_key`
-    radsort::sort_by_key(&mut sorted_sprites, |(_, _, transform, _)| {
+    radsort::sort_by_key(&mut sorted_sprites, |(_, _, transform, _, _)| {
         -transform.translation().z
     });
 
@@ -159,7 +160,7 @@ fn sprite_picking(
         let picks: Vec<(Entity, HitData)> = sorted_sprites
             .iter()
             .copied()
-            .filter_map(|(entity, sprite, sprite_transform, pickable)| {
+            .filter_map(|(entity, sprite, sprite_transform, anchor, pickable)| {
                 if blocked {
                     return None;
                 }
@@ -192,6 +193,7 @@ fn sprite_picking(
 
                 let Ok(cursor_pixel_space) = sprite.compute_pixel_space_point(
                     cursor_pos_sprite,
+                    *anchor,
                     &images,
                     &texture_atlas_layout,
                 ) else {

crates/bevy_sprite/src/render/mod.rs

@@ -1,6 +1,6 @@
 use core::ops::Range;
 
-use crate::{ComputedTextureSlices, ScalingMode, Sprite, SPRITE_SHADER_HANDLE};
+use crate::{Anchor, ComputedTextureSlices, ScalingMode, Sprite, SPRITE_SHADER_HANDLE};
 use bevy_asset::{AssetEvent, AssetId, Assets};
 use bevy_color::{ColorToComponents, LinearRgba};
 use bevy_core_pipeline::{
@@ -394,13 +394,14 @@ pub fn extract_sprites(
             &ViewVisibility,
             &Sprite,
             &GlobalTransform,
+            &Anchor,
             Option<&ComputedTextureSlices>,
         )>,
     >,
 ) {
     extracted_sprites.sprites.clear();
     extracted_slices.slices.clear();
-    for (main_entity, render_entity, view_visibility, sprite, transform, slices) in
+    for (main_entity, render_entity, view_visibility, sprite, transform, anchor, slices) in
         sprite_query.iter()
     {
         if !view_visibility.get() {
@@ -411,7 +412,7 @@ pub fn extract_sprites(
             let start = extracted_slices.slices.len();
             extracted_slices
                 .slices
-                .extend(slices.extract_slices(sprite));
+                .extend(slices.extract_slices(sprite, anchor.as_vec()));
             let end = extracted_slices.slices.len();
             extracted_sprites.sprites.push(ExtractedSprite {
                 main_entity,
@@ -451,7 +452,7 @@ pub fn extract_sprites(
                 flip_y: sprite.flip_y,
                 image_handle_id: sprite.image.id(),
                 kind: ExtractedSpriteKind::Single {
-                    anchor: sprite.anchor.as_vec(),
+                    anchor: anchor.as_vec(),
                     rect,
                     scaling_mode: sprite.image_mode.scale(),
                     // Pass the custom size

crates/bevy_sprite/src/sprite.rs

@@ -15,7 +15,7 @@ use crate::TextureSlicer;
 
 /// Describes a sprite to be rendered to a 2D camera
 #[derive(Component, Debug, Default, Clone, Reflect)]
-#[require(Transform, Visibility, SyncToRenderWorld, VisibilityClass)]
+#[require(Transform, Visibility, SyncToRenderWorld, VisibilityClass, Anchor)]
 #[reflect(Component, Default, Debug, Clone)]
 #[component(on_add = view::add_visibility_class::<Sprite>)]
 pub struct Sprite {
@@ -38,8 +38,6 @@ pub struct Sprite {
     /// When used with a [`TextureAtlas`], the rect
     /// is offset by the atlas's minimal (top-left) corner position.
     pub rect: Option<Rect>,
-    /// [`Anchor`] point of the sprite in the world
-    pub anchor: Anchor,
     /// How the sprite's image will be scaled.
     pub image_mode: SpriteImageMode,
 }
@@ -86,6 +84,7 @@ impl Sprite {
     pub fn compute_pixel_space_point(
         &self,
         point_relative_to_sprite: Vec2,
+        anchor: Anchor,
         images: &Assets<Image>,
         texture_atlases: &Assets<TextureAtlasLayout>,
     ) -> Result<Vec2, Vec2> {
@@ -112,7 +111,7 @@ impl Sprite {
         };
 
         let sprite_size = self.custom_size.unwrap_or_else(|| texture_rect.size());
-        let sprite_center = -self.anchor.as_vec() * sprite_size;
+        let sprite_center = -anchor.as_vec() * sprite_size;
 
         let mut point_relative_to_sprite_center = point_relative_to_sprite - sprite_center;
 
@@ -315,8 +314,14 @@ mod tests {
             ..Default::default()
         };
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(
+                point,
+                Anchor::default(),
+                &image_assets,
+                &texture_atlas_assets,
+            )
+        };
         assert_eq!(compute(Vec2::new(-2.0, -4.5)), Ok(Vec2::new(0.5, 9.5)));
         assert_eq!(compute(Vec2::new(0.0, 0.0)), Ok(Vec2::new(2.5, 5.0)));
         assert_eq!(compute(Vec2::new(0.0, 4.5)), Ok(Vec2::new(2.5, 0.5)));
@@ -334,7 +339,12 @@ mod tests {
 
         let compute = |point| {
             sprite
-                .compute_pixel_space_point(point, &image_assets, &texture_atlas_assets)
+                .compute_pixel_space_point(
+                    point,
+                    Anchor::default(),
+                    &image_assets,
+                    &texture_atlas_assets,
+                )
                 // Round to remove floating point errors.
                 .map(|x| (x * 1e5).round() / 1e5)
                 .map_err(|x| (x * 1e5).round() / 1e5)
@@ -355,12 +365,13 @@ mod tests {
 
         let sprite = Sprite {
             image,
-            anchor: Anchor::BOTTOM_LEFT,
             ..Default::default()
         };
+        let anchor = Anchor::BOTTOM_LEFT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(0.5, 9.5)), Ok(Vec2::new(0.5, 0.5)));
         assert_eq!(compute(Vec2::new(2.5, 5.0)), Ok(Vec2::new(2.5, 5.0)));
         assert_eq!(compute(Vec2::new(2.5, 9.5)), Ok(Vec2::new(2.5, 0.5)));
@@ -377,12 +388,13 @@ mod tests {
 
         let sprite = Sprite {
             image,
-            anchor: Anchor::TOP_RIGHT,
             ..Default::default()
         };
+        let anchor = Anchor::TOP_RIGHT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(-4.5, -0.5)), Ok(Vec2::new(0.5, 0.5)));
         assert_eq!(compute(Vec2::new(-2.5, -5.0)), Ok(Vec2::new(2.5, 5.0)));
         assert_eq!(compute(Vec2::new(-2.5, -0.5)), Ok(Vec2::new(2.5, 0.5)));
@@ -399,13 +411,14 @@ mod tests {
 
         let sprite = Sprite {
             image,
-            anchor: Anchor::BOTTOM_LEFT,
             flip_x: true,
             ..Default::default()
         };
+        let anchor = Anchor::BOTTOM_LEFT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(0.5, 9.5)), Ok(Vec2::new(4.5, 0.5)));
         assert_eq!(compute(Vec2::new(2.5, 5.0)), Ok(Vec2::new(2.5, 5.0)));
         assert_eq!(compute(Vec2::new(2.5, 9.5)), Ok(Vec2::new(2.5, 0.5)));
@@ -422,13 +435,14 @@ mod tests {
 
         let sprite = Sprite {
             image,
-            anchor: Anchor::TOP_RIGHT,
             flip_y: true,
             ..Default::default()
         };
+        let anchor = Anchor::TOP_RIGHT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(-4.5, -0.5)), Ok(Vec2::new(0.5, 9.5)));
         assert_eq!(compute(Vec2::new(-2.5, -5.0)), Ok(Vec2::new(2.5, 5.0)));
         assert_eq!(compute(Vec2::new(-2.5, -0.5)), Ok(Vec2::new(2.5, 9.5)));
@@ -446,12 +460,13 @@ mod tests {
         let sprite = Sprite {
             image,
             rect: Some(Rect::new(1.5, 3.0, 3.0, 9.5)),
-            anchor: Anchor::BOTTOM_LEFT,
             ..Default::default()
         };
+        let anchor = Anchor::BOTTOM_LEFT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(0.5, 0.5)), Ok(Vec2::new(2.0, 9.0)));
         // The pixel is outside the rect, but is still a valid pixel in the image.
         assert_eq!(compute(Vec2::new(2.0, 2.5)), Err(Vec2::new(3.5, 7.0)));
@@ -470,16 +485,17 @@ mod tests {
 
         let sprite = Sprite {
             image,
-            anchor: Anchor::BOTTOM_LEFT,
             texture_atlas: Some(TextureAtlas {
                 layout: texture_atlas,
                 index: 0,
             }),
             ..Default::default()
         };
+        let anchor = Anchor::BOTTOM_LEFT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(0.5, 0.5)), Ok(Vec2::new(1.5, 3.5)));
         // The pixel is outside the texture atlas, but is still a valid pixel in the image.
         assert_eq!(compute(Vec2::new(4.0, 2.5)), Err(Vec2::new(5.0, 1.5)));
@@ -498,7 +514,6 @@ mod tests {
 
         let sprite = Sprite {
             image,
-            anchor: Anchor::BOTTOM_LEFT,
             texture_atlas: Some(TextureAtlas {
                 layout: texture_atlas,
                 index: 0,
@@ -507,9 +522,11 @@ mod tests {
             rect: Some(Rect::new(1.5, 1.5, 3.0, 3.0)),
             ..Default::default()
         };
+        let anchor = Anchor::BOTTOM_LEFT;
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(point, anchor, &image_assets, &texture_atlas_assets)
+        };
         assert_eq!(compute(Vec2::new(0.5, 0.5)), Ok(Vec2::new(3.0, 3.5)));
         // The pixel is outside the texture atlas, but is still a valid pixel in the image.
         assert_eq!(compute(Vec2::new(4.0, 2.5)), Err(Vec2::new(6.5, 1.5)));
@@ -529,8 +546,14 @@ mod tests {
             ..Default::default()
         };
 
-        let compute =
+        let compute = |point| {
-            |point| sprite.compute_pixel_space_point(point, &image_assets, &texture_atlas_assets);
+            sprite.compute_pixel_space_point(
+                point,
+                Anchor::default(),
+                &image_assets,
+                &texture_atlas_assets,
+            )
+        };
         assert_eq!(compute(Vec2::new(30.0, 15.0)), Ok(Vec2::new(4.0, 1.0)));
         assert_eq!(compute(Vec2::new(-10.0, -15.0)), Ok(Vec2::new(2.0, 4.0)));
         // The pixel is outside the texture atlas, but is still a valid pixel in the image.

crates/bevy_sprite/src/texture_slice/computed_slices.rs

@@ -1,6 +1,5 @@
-use crate::{ExtractedSlice, Sprite, SpriteImageMode, TextureAtlasLayout};
-
 use super::TextureSlice;
+use crate::{ExtractedSlice, Sprite, SpriteImageMode, TextureAtlasLayout};
 use bevy_asset::{AssetEvent, Assets};
 use bevy_ecs::prelude::*;
 use bevy_image::Image;
@@ -23,6 +22,7 @@ impl ComputedTextureSlices {
     pub(crate) fn extract_slices<'a>(
         &'a self,
         sprite: &'a Sprite,
+        anchor: Vec2,
     ) -> impl ExactSizeIterator<Item = ExtractedSlice> + 'a {
         let mut flip = Vec2::ONE;
         if sprite.flip_x {
@@ -31,7 +31,7 @@ impl ComputedTextureSlices {
         if sprite.flip_y {
             flip.y *= -1.0;
         }
-        let anchor = sprite.anchor.as_vec()
+        let anchor = anchor
             * sprite
                 .custom_size
                 .unwrap_or(sprite.rect.unwrap_or_default().size());

examples/picking/sprite_picking.rs

@@ -72,9 +72,9 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                             image: asset_server.load("branding/bevy_bird_dark.png"),
                             custom_size: Some(sprite_size),
                             color: Color::srgb(1.0, 0.0, 0.0),
-                            anchor: anchor.to_owned(),
                             ..default()
                         },
+                        anchor.to_owned(),
                         // 3x3 grid of anchor examples by changing transform
                         Transform::from_xyz(i * len - len, j * len - len, 0.0)
                             .with_scale(Vec3::splat(1.0 + (i - 1.0) * 0.2))

examples/testbed/2d.rs

@@ -246,10 +246,10 @@ mod text {
                     Sprite {
                         color: palettes::tailwind::GRAY_900.into(),
                         custom_size: Some(Vec2::new(bounds.width.unwrap(), bounds.height.unwrap())),
-                        anchor,
                         ..Default::default()
                     },
                     Transform::from_translation(dest - Vec3::Z),
+                    anchor,
                     DespawnOnExitState(super::Scene::Text),
                 ));
             }
@@ -273,12 +273,12 @@ mod sprite {
             commands.spawn((
                 Sprite {
                     image: asset_server.load("branding/bevy_logo_dark.png"),
-                    anchor,
                     flip_x,
                     flip_y,
                     color,
                     ..default()
                 },
+                anchor,
                 DespawnOnExitState(super::Scene::Sprite),
             ));
         }

release-content/migration-guides/anchor_is_removed_from_sprite.md

@@ -0,0 +1,6 @@
+---
+title: `Anchor` is now a required component on `Sprite`
+pull_requests: [18393]
+---
+
+The `anchor` field has been removed from `Sprite`. Instead the `Anchor` component is now a required component on `Sprite`.