Add TransformBundle and use it as Sub-Bundle

crates/bevy_gltf/src/loader.rs

@@ -20,7 +20,8 @@ use bevy_render::{
 use bevy_scene::Scene;
 use bevy_transform::{
     hierarchy::{BuildWorldChildren, WorldChildBuilder},
-    prelude::{GlobalTransform, Transform},
+    prelude::Transform,
+    TransformBundle,
 };
 use gltf::{
     mesh::Mode,
@@ -280,7 +281,7 @@ async fn load_gltf<'a, 'b>(
         let mut world = World::default();
         world
             .spawn()
-            .insert_bundle((Transform::identity(), GlobalTransform::identity()))
+            .insert_bundle(TransformBundle::identity())
             .with_children(|parent| {
                 for node in scene.nodes() {
                     let result = load_node(&node, parent, load_context, &buffer_data);
@@ -450,9 +451,8 @@ fn load_node(
 ) -> Result<(), GltfError> {
     let transform = gltf_node.transform();
     let mut gltf_error = None;
-    let mut node = world_builder.spawn_bundle((
+    let mut node = world_builder.spawn_bundle(TransformBundle::from_transform(
         Transform::from_matrix(Mat4::from_cols_array_2d(&transform.matrix())),
-        GlobalTransform::identity(),
     ));
 
     if let Some(name) = gltf_node.name() {

crates/bevy_pbr/src/entity.rs

@@ -8,7 +8,7 @@ use bevy_render::{
     prelude::Visible,
     render_graph::base::MainPass,
 };
-use bevy_transform::prelude::{GlobalTransform, Transform};
+use bevy_transform::prelude::TransformBundle;
 
 /// A component bundle for "pbr mesh" entities
 #[derive(Bundle)]
@@ -19,8 +19,8 @@ pub struct PbrBundle {
     pub draw: Draw,
     pub visible: Visible,
     pub render_pipelines: RenderPipelines,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 impl Default for PbrBundle {
@@ -35,7 +35,6 @@ impl Default for PbrBundle {
             main_pass: Default::default(),
             draw: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 }
@@ -44,6 +43,6 @@ impl Default for PbrBundle {
 #[derive(Debug, Bundle, Default)]
 pub struct PointLightBundle {
     pub point_light: PointLight,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }

crates/bevy_render/src/entity.rs

@@ -11,7 +11,7 @@ use crate::{
 use base::MainPass;
 use bevy_asset::Handle;
 use bevy_ecs::bundle::Bundle;
-use bevy_transform::components::{GlobalTransform, Transform};
+use bevy_transform::{components::Transform, TransformBundle};
 
 /// A component bundle for "mesh" entities
 #[derive(Bundle, Default)]
@@ -21,8 +21,8 @@ pub struct MeshBundle {
     pub visible: Visible,
     pub render_pipelines: RenderPipelines,
     pub main_pass: MainPass,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 /// Component bundle for camera entities with perspective projection
@@ -33,8 +33,8 @@ pub struct PerspectiveCameraBundle {
     pub camera: Camera,
     pub perspective_projection: PerspectiveProjection,
     pub visible_entities: VisibleEntities,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 impl PerspectiveCameraBundle {
@@ -51,7 +51,6 @@ impl PerspectiveCameraBundle {
             perspective_projection: Default::default(),
             visible_entities: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 }
@@ -66,7 +65,6 @@ impl Default for PerspectiveCameraBundle {
             perspective_projection: Default::default(),
             visible_entities: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 }
@@ -79,8 +77,8 @@ pub struct OrthographicCameraBundle {
     pub camera: Camera,
     pub orthographic_projection: OrthographicProjection,
     pub visible_entities: VisibleEntities,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 impl OrthographicCameraBundle {
@@ -99,8 +97,7 @@ impl OrthographicCameraBundle {
                 ..Default::default()
             },
             visible_entities: Default::default(),
-            transform: Transform::from_xyz(0.0, 0.0, far - 0.1),
-            global_transform: Default::default(),
+            transform: Transform::from_xyz(0.0, 0.0, far - 0.1).into(),
         }
     }
 
@@ -117,7 +114,6 @@ impl OrthographicCameraBundle {
             },
             visible_entities: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 
@@ -130,7 +126,6 @@ impl OrthographicCameraBundle {
             orthographic_projection: Default::default(),
             visible_entities: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 }

crates/bevy_sprite/src/entity.rs

@@ -10,7 +10,7 @@ use bevy_render::{
     prelude::{Draw, Visible},
     render_graph::base::MainPass,
 };
-use bevy_transform::prelude::{GlobalTransform, Transform};
+use bevy_transform::TransformBundle;
 
 #[derive(Bundle, Clone)]
 pub struct SpriteBundle {
@@ -21,8 +21,8 @@ pub struct SpriteBundle {
     pub draw: Draw,
     pub visible: Visible,
     pub render_pipelines: RenderPipelines,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 impl Default for SpriteBundle {
@@ -41,7 +41,6 @@ impl Default for SpriteBundle {
             sprite: Default::default(),
             material: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 }
@@ -60,8 +59,8 @@ pub struct SpriteSheetBundle {
     pub render_pipelines: RenderPipelines,
     pub main_pass: MainPass,
     pub mesh: Handle<Mesh>, // TODO: maybe abstract this out
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 impl Default for SpriteSheetBundle {
@@ -80,7 +79,6 @@ impl Default for SpriteSheetBundle {
             sprite: Default::default(),
             texture_atlas: Default::default(),
             transform: Default::default(),
-            global_transform: Default::default(),
         }
     }
 }

crates/bevy_text/src/text2d.rs

@@ -14,7 +14,7 @@ use bevy_render::{
     renderer::RenderResourceBindings,
 };
 use bevy_sprite::{TextureAtlas, QUAD_HANDLE};
-use bevy_transform::prelude::{GlobalTransform, Transform};
+use bevy_transform::prelude::{GlobalTransform, TransformBundle};
 use bevy_window::Windows;
 use glyph_brush_layout::{HorizontalAlign, VerticalAlign};
 
@@ -27,10 +27,10 @@ pub struct Text2dBundle {
     pub draw: Draw,
     pub visible: Visible,
     pub text: Text,
-    pub transform: Transform,
-    pub global_transform: GlobalTransform,
     pub main_pass: MainPass,
     pub text_2d_size: Text2dSize,
+    #[bundle]
+    pub transform: TransformBundle,
 }
 
 impl Default for Text2dBundle {
@@ -44,12 +44,11 @@ impl Default for Text2dBundle {
                 ..Default::default()
             },
             text: Default::default(),
-            transform: Default::default(),
-            global_transform: Default::default(),
             main_pass: MainPass {},
             text_2d_size: Text2dSize {
                 size: Size::default(),
             },
+            transform: Default::default(),
         }
     }
 }

crates/bevy_transform/src/components/global_transform.rs

@@ -7,8 +7,9 @@ use std::ops::Mul;
 /// Describe the position of an entity relative to the reference frame.
 ///
 /// * To place or move an entity, you should set its [`Transform`].
-/// * To be displayed, an entity must have both a [`Transform`] and a [`GlobalTransform`].
 /// * To get the global position of an entity, you should get its [`GlobalTransform`].
+/// * To be displayed, an entity must have both a [`Transform`] and a [`GlobalTransform`].
+///   * You may use the [`TransformBundle`] to guarantee this.
 ///
 /// ## [`Transform`] and [`GlobalTransform`]
 ///
@@ -20,16 +21,6 @@ use std::ops::Mul;
 /// [`GlobalTransform`] is updated from [`Transform`] in the system
 /// [`transform_propagate_system`](crate::transform_propagate_system::transform_propagate_system).
 ///
-/// In pseudo code:
-/// ```ignore
-/// for entity in entities_without_parent:
-///     set entity.global_transform to entity.transform
-///     recursively:
-///         set parent to current entity
-///         for child in parent.children:
-///             set child.global_transform to parent.global_transform * child.transform
-/// ```
-///
 /// This system runs in stage [`CoreStage::PostUpdate`](crate::CoreStage::PostUpdate). If you
 /// update the[`Transform`] of an entity in this stage or after, you will notice a 1 frame lag
 /// before the [`GlobalTransform`] is updated.

crates/bevy_transform/src/components/transform.rs

@@ -8,8 +8,9 @@ use std::ops::Mul;
 /// to its parent position.
 ///
 /// * To place or move an entity, you should set its [`Transform`].
-/// * To be displayed, an entity must have both a [`Transform`] and a [`GlobalTransform`].
 /// * To get the global position of an entity, you should get its [`GlobalTransform`].
+/// * To be displayed, an entity must have both a [`Transform`] and a [`GlobalTransform`].
+///   * You may use the [`TransformBundle`] to guarantee this.
 ///
 /// ## [`Transform`] and [`GlobalTransform`]
 ///
@@ -21,16 +22,6 @@ use std::ops::Mul;
 /// [`GlobalTransform`] is updated from [`Transform`] in the system
 /// [`transform_propagate_system`](crate::transform_propagate_system::transform_propagate_system).
 ///
-/// In pseudo code:
-/// ```ignore
-/// for entity in entities_without_parent:
-///     set entity.global_transform to entity.transform
-///     recursively:
-///         set parent to current entity
-///         for child in parent.children:
-///             set child.global_transform to parent.global_transform * child.transform
-/// ```
-///
 /// This system runs in stage [`CoreStage::PostUpdate`](crate::CoreStage::PostUpdate). If you
 /// update the[`Transform`] of an entity in this stage or after, you will notice a 1 frame lag
 /// before the [`GlobalTransform`] is updated.

crates/bevy_transform/src/lib.rs

@@ -4,13 +4,73 @@ pub mod transform_propagate_system;
 
 pub mod prelude {
     #[doc(hidden)]
-    pub use crate::{components::*, hierarchy::*, TransformPlugin};
+    pub use crate::{components::*, hierarchy::*, TransformBundle, TransformPlugin};
 }
 
 use bevy_app::prelude::*;
-use bevy_ecs::schedule::{ParallelSystemDescriptorCoercion, SystemLabel};
+use bevy_ecs::{
+    bundle::Bundle,
+    schedule::{ParallelSystemDescriptorCoercion, SystemLabel},
+};
 use prelude::{parent_update_system, Children, GlobalTransform, Parent, PreviousParent, Transform};
 
+/// A [`Bundle`] of the [`Transform`] and [`GlobalTransform`]
+/// [`Component`](bevy_ecs::component::Component)s, which describe the position of an entity.
+///
+/// * To place or move an entity, you should set its [`Transform`].
+/// * To get the global position of an entity, you should get its [`GlobalTransform`].
+/// * To be displayed, an entity must have both a [`Transform`] and a [`GlobalTransform`].
+///   * You may use the [`TransformBundle`] to guarantee this.
+///
+/// ## [`Transform`] and [`GlobalTransform`]
+///
+/// [`Transform`] is the position of an entity relative to its parent position, or the reference
+/// frame if it doesn't have a [`Parent`](Parent).
+///
+/// [`GlobalTransform`] is the position of an entity relative to the reference frame.
+///
+/// [`GlobalTransform`] is updated from [`Transform`] in the system
+/// [`transform_propagate_system`](crate::transform_propagate_system::transform_propagate_system).
+///
+/// This system runs in stage [`CoreStage::PostUpdate`](crate::CoreStage::PostUpdate). If you
+/// update the[`Transform`] of an entity in this stage or after, you will notice a 1 frame lag
+/// before the [`GlobalTransform`] is updated.
+#[derive(Default, Bundle, Clone, Debug)]
+pub struct TransformBundle {
+    pub local: Transform,
+    pub global: GlobalTransform,
+}
+
+impl TransformBundle {
+    /// Creates a new [`TransformBundle`] from a [`Transform`] and leaving [`GlobalTransform`] with
+    /// no translation, rotation, and a scale of 1 on all axes.
+    #[inline]
+    pub fn from_transform(transform: Transform) -> Self {
+        TransformBundle {
+            local: transform,
+            ..Default::default()
+        }
+    }
+
+    /// Creates a new identity [`TransformBundle`], with no translation, rotation, and a scale of 1
+    /// on all axes.
+    #[inline]
+    pub const fn identity() -> Self {
+        TransformBundle {
+            local: Transform::identity(),
+            // Note: `..Default::default()` cannot be used here, because it isn't const
+            global: GlobalTransform::identity(),
+        }
+    }
+}
+
+impl From<Transform> for TransformBundle {
+    #[inline]
+    fn from(transform: Transform) -> Self {
+        Self::from_transform(transform)
+    }
+}
+
 #[derive(Default)]
 pub struct TransformPlugin;