54006b107b
# Objective A big step in the migration to required components: meshes and materials! ## Solution As per the [selected proposal](https://hackmd.io/@bevy/required_components/%2Fj9-PnF-2QKK0on1KQ29UWQ): - Deprecate `MaterialMesh2dBundle`, `MaterialMeshBundle`, and `PbrBundle`. - Add `Mesh2d` and `Mesh3d` components, which wrap a `Handle<Mesh>`. - Add `MeshMaterial2d<M: Material2d>` and `MeshMaterial3d<M: Material>`, which wrap a `Handle<M>`. - Meshes *without* a mesh material should be rendered with a default material. The existence of a material is determined by `HasMaterial2d`/`HasMaterial3d`, which is required by `MeshMaterial2d`/`MeshMaterial3d`. This gets around problems with the generics. Previously: ```rust commands.spawn(MaterialMesh2dBundle { mesh: meshes.add(Circle::new(100.0)).into(), material: materials.add(Color::srgb(7.5, 0.0, 7.5)), transform: Transform::from_translation(Vec3::new(-200., 0., 0.)), ..default() }); ``` Now: ```rust commands.spawn(( Mesh2d(meshes.add(Circle::new(100.0))), MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))), Transform::from_translation(Vec3::new(-200., 0., 0.)), )); ``` If the mesh material is missing, previously nothing was rendered. Now, it renders a white default `ColorMaterial` in 2D and a `StandardMaterial` in 3D (this can be overridden). Below, only every other entity has a material:   Why white? This is still open for discussion, but I think white makes sense for a *default* material, while *invalid* asset handles pointing to nothing should have something like a pink material to indicate that something is broken (I don't handle that in this PR yet). This is kind of a mix of Godot and Unity: Godot just renders a white material for non-existent materials, while Unity renders nothing when no materials exist, but renders pink for invalid materials. I can also change the default material to pink if that is preferable though. ## Testing I ran some 2D and 3D examples to test if anything changed visually. I have not tested all examples or features yet however. If anyone wants to test more extensively, it would be appreciated! ## Implementation Notes - The relationship between `bevy_render` and `bevy_pbr` is weird here. `bevy_render` needs `Mesh3d` for its own systems, but `bevy_pbr` has all of the material logic, and `bevy_render` doesn't depend on it. I feel like the two crates should be refactored in some way, but I think that's out of scope for this PR. - I didn't migrate meshlets to required components yet. That can probably be done in a follow-up, as this is already a huge PR. - It is becoming increasingly clear to me that we really, *really* want to disallow raw asset handles as components. They caused me a *ton* of headache here already, and it took me a long time to find every place that queried for them or inserted them directly on entities, since there were no compiler errors for it. If we don't remove the `Component` derive, I expect raw asset handles to be a *huge* footgun for users as we transition to wrapper components, especially as handles as components have been the norm so far. I personally consider this to be a blocker for 0.15: we need to migrate to wrapper components for asset handles everywhere, and remove the `Component` derive. Also see https://github.com/bevyengine/bevy/issues/14124. --- ## Migration Guide Asset handles for meshes and mesh materials must now be wrapped in the `Mesh2d` and `MeshMaterial2d` or `Mesh3d` and `MeshMaterial3d` components for 2D and 3D respectively. Raw handles as components no longer render meshes. Additionally, `MaterialMesh2dBundle`, `MaterialMeshBundle`, and `PbrBundle` have been deprecated. Instead, use the mesh and material components directly. Previously: ```rust commands.spawn(MaterialMesh2dBundle { mesh: meshes.add(Circle::new(100.0)).into(), material: materials.add(Color::srgb(7.5, 0.0, 7.5)), transform: Transform::from_translation(Vec3::new(-200., 0., 0.)), ..default() }); ``` Now: ```rust commands.spawn(( Mesh2d(meshes.add(Circle::new(100.0))), MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))), Transform::from_translation(Vec3::new(-200., 0., 0.)), )); ``` If the mesh material is missing, a white default material is now used. Previously, nothing was rendered if the material was missing. The `WithMesh2d` and `WithMesh3d` query filter type aliases have also been removed. Simply use `With<Mesh2d>` or `With<Mesh3d>`. --------- Co-authored-by: Tim Blackbird <justthecooldude@gmail.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
113 lines
3.5 KiB
Markdown
113 lines
3.5 KiB
Markdown
# B0004
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A runtime warning.
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An [`Entity`] with a hierarchy-inherited component has a [`Parent`]
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without the hierarchy-inherited component in question.
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The hierarchy-inherited components defined in bevy include:
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- [`InheritedVisibility`]
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- [`GlobalTransform`]
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Third party plugins may also define their own hierarchy components, so
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read the warning message carefully and pay attention to the exact type
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of the missing component.
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To fix this warning, add the missing hierarchy component to all ancestors
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of entities with the hierarchy component you wish to use.
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The following code will cause a warning to be emitted:
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```rust,no_run
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use bevy::prelude::*;
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// WARNING: this code is buggy
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fn setup_cube(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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commands
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.spawn(Transform::default())
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.with_children(|parent| {
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// cube
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parent.spawn((
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Mesh3d(meshes.add(Cuboid::default())),
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MeshMaterial3d(materials.add(Color::rgb(0.8, 0.7, 0.6))),
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Transform::from_xyz(0.0, 0.5, 0.0),
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));
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});
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// camera
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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}
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup_cube)
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.run();
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}
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```
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This code **will not** show a cube on screen.
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This is because the entity spawned with `commands.spawn(…)`
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doesn't have a [`ViewVisibility`] or [`InheritedVisibility`] component.
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Since the cube is spawned as a child of an entity without the
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visibility components, it will not be visible at all.
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To fix this, you must also add a [`Visibility`] component.
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It automatically adds the other relevant visibility components for you:
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```rust,no_run
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use bevy::prelude::*;
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fn setup_cube(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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commands
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.spawn((Transform::default(), Visibility::default()))
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.with_children(|parent| {
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// cube
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parent.spawn((
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Mesh3d(meshes.add(Cuboid::default())),
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MeshMaterial3d(materials.add(Color::rgb(0.8, 0.7, 0.6))),
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Transform::from_xyz(0.0, 0.5, 0.0),
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));
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});
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// camera
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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}
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup_cube)
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.run();
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}
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```
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A similar problem occurs when the [`GlobalTransform`] component is missing.
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However, it will be automatically inserted whenever `Transform` is
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inserted, as it is a required component.
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You will most likely encounter this warning when loading a scene
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as a child of a pre-existing [`Entity`] that does not have the proper components.
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[`InheritedVisibility`]: https://docs.rs/bevy/*/bevy/render/view/struct.InheritedVisibility.html
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[`ViewVisibility`]: https://docs.rs/bevy/*/bevy/render/view/struct.ViewVisibility.html
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[`Visibility`]: https://docs.rs/bevy/*/bevy/render/view/struct.Visibility.html
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[`GlobalTransform`]: https://docs.rs/bevy/*/bevy/transform/components/struct.GlobalTransform.html
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[`Parent`]: https://docs.rs/bevy/*/bevy/hierarchy/struct.Parent.html
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[`Entity`]: https://docs.rs/bevy/*/bevy/ecs/entity/struct.Entity.html
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