6c5403cf47
# Objective A common pitfall since 0.8 is the requirement on `ComputedVisibility` being present on all ancestors of an entity that itself has `ComputedVisibility`, without which, the entity becomes invisible. I myself hit the issue and got very confused, and saw a few people hit it as well, so it makes sense to provide a hint of what to do when such a situation is encountered. - Fixes #5849 - Closes #5616 - Closes #2277 - Closes #5081 ## Solution We now check that all entities with both a `Parent` and a `ComputedVisibility` component have parents that themselves have a `ComputedVisibility` component. Note that the warning is only printed once. We also add a similar warning to `GlobalTransform`. This only emits a warning. Because sometimes it could be an intended behavior. Alternatives: - Do nothing and keep repeating to newcomers how to avoid recurring pitfalls - Make the transform and visibility propagation tolerant to missing components (#5616) - Probably archetype invariants, though the current draft would not allow detecting that kind of errors --- ## Changelog - Add a warning when encountering dubious component hierarchy structure Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
90 lines
3.2 KiB
Rust
90 lines
3.2 KiB
Rust
use std::marker::PhantomData;
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use bevy_app::{App, CoreStage, Plugin};
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use bevy_core::Name;
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use bevy_ecs::{prelude::*, schedule::ShouldRun};
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use bevy_log::warn;
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use bevy_utils::{get_short_name, HashSet};
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use crate::Parent;
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/// When enabled, runs [`check_hierarchy_component_has_valid_parent<T>`].
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///
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/// This resource is added by [`ValidParentCheckPlugin<T>`].
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/// It is enabled on debug builds and disabled in release builds by default,
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/// you can update this resource at runtime to change the default behavior.
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#[derive(Resource)]
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pub struct ReportHierarchyIssue<T> {
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/// Whether to run [`check_hierarchy_component_has_valid_parent<T>`].
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pub enabled: bool,
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_comp: PhantomData<fn(T)>,
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}
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impl<T> Default for ReportHierarchyIssue<T> {
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fn default() -> Self {
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Self {
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enabled: cfg!(debug_assertions),
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_comp: PhantomData,
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}
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}
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}
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/// System to print a warning for each `Entity` with a `T` component
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/// which parent hasn't a `T` component.
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///
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/// Hierarchy propagations are top-down, and limited only to entities
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/// with a specific component (such as `ComputedVisibility` and `GlobalTransform`).
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/// This means that entities with one of those component
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/// and a parent without the same component is probably a programming error.
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/// (See B0004 explanation linked in warning message)
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pub fn check_hierarchy_component_has_valid_parent<T: Component>(
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parent_query: Query<
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(Entity, &Parent, Option<&Name>),
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(With<T>, Or<(Changed<Parent>, Added<T>)>),
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>,
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component_query: Query<(), With<T>>,
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mut already_diagnosed: Local<HashSet<Entity>>,
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) {
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for (entity, parent, name) in &parent_query {
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let parent = parent.get();
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if !component_query.contains(parent) && !already_diagnosed.contains(&entity) {
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already_diagnosed.insert(entity);
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warn!(
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"warning[B0004]: {name} with the {ty_name} component has a parent without {ty_name}.\n\
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This will cause inconsistent behaviors! See https://bevyengine.org/learn/errors/#B0004",
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ty_name = get_short_name(std::any::type_name::<T>()),
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name = name.map_or("An entity".to_owned(), |s| format!("The {s} entity")),
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);
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}
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}
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}
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/// Run criteria that only allows running when [`ReportHierarchyIssue<T>`] is enabled.
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pub fn on_hierarchy_reports_enabled<T>(report: Res<ReportHierarchyIssue<T>>) -> ShouldRun
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where
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T: Component,
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{
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report.enabled.into()
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}
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/// Print a warning for each `Entity` with a `T` component
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/// whose parent doesn't have a `T` component.
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///
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/// See [`check_hierarchy_component_has_valid_parent`] for details.
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pub struct ValidParentCheckPlugin<T: Component>(PhantomData<fn() -> T>);
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impl<T: Component> Default for ValidParentCheckPlugin<T> {
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fn default() -> Self {
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Self(PhantomData)
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}
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}
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impl<T: Component> Plugin for ValidParentCheckPlugin<T> {
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fn build(&self, app: &mut App) {
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app.init_resource::<ReportHierarchyIssue<T>>()
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.add_system_to_stage(
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CoreStage::Last,
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check_hierarchy_component_has_valid_parent::<T>
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.with_run_criteria(on_hierarchy_reports_enabled::<T>),
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);
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}
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}
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