02b520b4e8
# Objective Fix #8267. Fixes half of #7840. The `ComputedVisibility` component contains two flags: hierarchy visibility, and view visibility (whether its visible to any cameras). Due to the modular and open-ended way that view visibility is computed, it triggers change detection every single frame, even when the value does not change. Since hierarchy visibility is stored in the same component as view visibility, this means that change detection for inherited visibility is completely broken. At the company I work for, this has become a real issue. We are using change detection to only re-render scenes when necessary. The broken state of change detection for computed visibility means that we have to to rely on the non-inherited `Visibility` component for now. This is workable in the early stages of our project, but since we will inevitably want to use the hierarchy, we will have to either: 1. Roll our own solution for computed visibility. 2. Fix the issue for everyone. ## Solution Split the `ComputedVisibility` component into two: `InheritedVisibilty` and `ViewVisibility`. This allows change detection to behave properly for `InheritedVisibility`. View visiblity is still erratic, although it is less useful to be able to detect changes for this flavor of visibility. Overall, this actually simplifies the API. Since the visibility system consists of self-explaining components, it is much easier to document the behavior and usage. This approach is more modular and "ECS-like" -- one could strip out the `ViewVisibility` component entirely if it's not needed, and rely only on inherited visibility. --- ## Changelog - `ComputedVisibility` has been removed in favor of: `InheritedVisibility` and `ViewVisiblity`. ## Migration Guide The `ComputedVisibilty` component has been split into `InheritedVisiblity` and `ViewVisibility`. Replace any usages of `ComputedVisibility::is_visible_in_hierarchy` with `InheritedVisibility::get`, and replace `ComputedVisibility::is_visible_in_view` with `ViewVisibility::get`. ```rust // Before: commands.spawn(VisibilityBundle { visibility: Visibility::Inherited, computed_visibility: ComputedVisibility::default(), }); // After: commands.spawn(VisibilityBundle { visibility: Visibility::Inherited, inherited_visibility: InheritedVisibility::default(), view_visibility: ViewVisibility::default(), }); ``` ```rust // Before: fn my_system(q: Query<&ComputedVisibilty>) { for vis in &q { if vis.is_visible_in_hierarchy() { // After: fn my_system(q: Query<&InheritedVisibility>) { for inherited_visibility in &q { if inherited_visibility.get() { ``` ```rust // Before: fn my_system(q: Query<&ComputedVisibilty>) { for vis in &q { if vis.is_visible_in_view() { // After: fn my_system(q: Query<&ViewVisibility>) { for view_visibility in &q { if view_visibility.get() { ``` ```rust // Before: fn my_system(mut q: Query<&mut ComputedVisibilty>) { for vis in &mut q { vis.set_visible_in_view(); // After: fn my_system(mut q: Query<&mut ViewVisibility>) { for view_visibility in &mut q { view_visibility.set(); ``` --------- Co-authored-by: Robert Swain <robert.swain@gmail.com>
4 KiB
B0004
A runtime warning.
An Entity with a hierarchy-inherited component has a Parent
without the hierarchy-inherited component in question.
The hierarchy-inherited components defined in bevy include:
Third party plugins may also define their own hierarchy components, so read the warning message carefully and pay attention to the exact type of the missing component.
To fix this warning, add the missing hierarchy component to all ancestors of entities with the hierarchy component you wish to use.
The following code will cause a warning to be emitted:
use bevy::prelude::*;
// WARNING: this code is buggy
fn setup_cube(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
commands
.spawn(TransformBundle::default())
.with_children(|parent| {
// cube
parent.spawn(PbrBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
transform: Transform::from_xyz(0.0, 0.5, 0.0),
..default()
});
});
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
}
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup_cube)
.run();
}
This code will not show a cube on screen.
This is because the entity spawned with commands.spawn(…)
doesn't have a ViewVisibility or InheritedVisibility component.
Since the cube is spawned as a child of an entity without the
visibility components, it will not be visible at all.
To fix this, you must use SpatialBundle over TransformBundle,
as follows:
use bevy::prelude::*;
fn setup_cube(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
commands
// We use SpatialBundle instead of TransformBundle, it contains the
// visibility components needed to display the cube,
// In addition to the Transform and GlobalTransform components.
.spawn(SpatialBundle::default())
.with_children(|parent| {
// cube
parent.spawn(PbrBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
transform: Transform::from_xyz(0.0, 0.5, 0.0),
..default()
});
});
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
}
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup_cube)
.run();
}
A similar problem occurs when the GlobalTransform component is missing.
However, when a parent GlobalTransform is missing,
it will simply prevent all transform propagation,
including when updating the Transform component of the child.
You will most likely encounter this warning when loading a scene
as a child of a pre-existing Entity that does not have the proper components.