-
-
Notifications
You must be signed in to change notification settings - Fork 112
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Speed up ColliderTransform
propagation and extract collider hierarchy logic into ColliderHierarchyPlugin
#377
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Jondolf
added
C-Performance
Improvements or questions related to performance
C-Breaking-Change
This change removes or changes behavior or APIs, requiring users to adapt
labels
Jun 19, 2024
Hmm, I might be able to use a similar approach for the "normal" Bevy transform propagation that we run in like four other places... I'll test this in a follow-up |
I have the follow-up implemented, and it reworks this further. I'll merge this first though, and open the follow-up right after |
Jondolf
added a commit
that referenced
this pull request
Jun 21, 2024
…380) # Objective #377 refactored collider hierarchy logic and extracted it into a `ColliderHierarchyPlugin<C: ScalableCollider>`, along with significantly speeding up `ColliderTransform` propagation using a `ColliderAncestor` marker component to ignore trees that don't have colliders. However, a similar marker component approach can *also* be used to speed up the many copies of transform propagation that the engine has. By limiting the propagation runs to physics entities, we could drastically reduce the overhead for scenes with lots of non-physics entities, further addressing #356. ## Solution - Extract the ancestor marker logic from `ColliderHierarchyPlugin` into an `AncestorMarkerPlugin<C: Component>` that adds an `AncestorMarker<C>` component for all ancestors of entities with the given component `C`. The logic was also refactored to be more robust and fix some edge cases and fully support hierarchy changes, along with adding more tests. - Use this plugin in `SyncPlugin` to mark rigid body ancestors. - Define custom transform propagation systems that *only* traverse trees that have physics entities (rigid bodies or colliders). See the comments in `sync.rs` above the propagation systems to see how this works. - To support custom collision backends without having to add generics to all the propagation systems, and to avoid needing to unnecessarily duplicate systems, the `ColliderBackendPlugin` now adds a general, automatically managed `ColliderMarker` component for all colliders, which allows filtering collider entities without knowing the collider type. This lets us get rid of the generics on `ColliderHierarchyPlugin`! - I also changed some scheduling and system sets in the `PrepareSet` to account for some changes and to be more logical. ## Results Test scene: 12 substeps, 1 root entity, 100,000 child entities. All entities have just a `SpatialBundle`, and one child entity also has a `Collider`. - Before [#377](#377): ~22 FPS - After [#377](#377): ~200 FPS - After this PR: ~490 FPS Of course, this scene is not very representative of an actual game scene, but it does show just how much of an impact the transform propagation was having. A *lot* of games (probably most of them) do have many more non-physics entities than physics entities, and the overhead added by the marker components and new checks should be very minimal in comparison. --- ## Migration Guide Some `PrepareSet` system sets have changed order. Before: 1. `PreInit` 2. `PropagateTransforms` 3. `InitRigidBodies` 4. `InitMassProperties` 5. `InitColliders` 6. `InitTransforms` 7. `Finalize` After: 1. `PreInit` 2. `InitRigidBodies` 3. `InitColliders` 4. `PropagateTransforms` 5. `InitMassProperties` 6. `InitTransforms` 7. `Finalize` Additionally, the `ColliderHierarchyPlugin` added in #377 no longer needs generics. The plugin is new anyway however, so this isn't really a breaking change.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Labels
C-Breaking-Change
This change removes or changes behavior or APIs, requiring users to adapt
C-Performance
Improvements or questions related to performance
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Objective
Note: This is for the
bevy-0.14
branch, because it uses new observer functionality (although it's not strictly necessary). It will be merged tomain
for the upcoming release.Fixes #356.
To handle transforms in collider hierarchies properly, the engine must currently propagate a
ColliderTransform
component down the hierarchy several times per frame. This is made even worse by the fact that this propagation is done at every substep, not just once or twice per frame.This wouldn't be too bad if it only affected physics entities, but the current system traverses through all entities that have a
Transform
. As reported in #356, this leads to absolutely awful performance for scenes with a large number of non-physics entities. This means that the engine scales very poorly with entity count, which is unacceptable.Solution
Speed up propagation with
ColliderAncestor
When colliders are added as children, automatically mark all ancestors with the
ColliderAncestor
component. Similarly, clean up the markers when a collider is removed.ColliderTransform
is only propagated down trees withColliderAncestor
entities. This way, we can essentially skip all unnecessary propagation.In a test scene with one root entity, 100,000 child entities, and 12 substeps, I was previously getting ~22 fps even though the entities only had a
SpatialBundle
and no physics components. With the changes in this PR, I now get ~200 fps. Adding colliders to individual entities doesn't impact performance in any meaningful way, as the propagation is only done for those entities.Note that this propagation will be even less of an issue in the upcoming Avian release, because there it doesn't even need to be run in the substepping loop.
The
ColliderAncestor
logic has a pretty comprehensive unit test for adding and removing colliders in a hierarchy, but I haven't verified yet if simply changing theParent
without moving theCollider
works as expected. Adding more tests and potentially fixing these more niche cases can be done in a follow-up.Add
ColliderHierarchyPlugin
The
ColliderBackendPlugin
was getting big, so I decided to extract the logic related to hierarchies andColliderTransform
into a newColliderHierarchyPlugin
.Ideally, you could use the plugins fully independently and for example completely abandon hierarchies if you wanted to, but currently, they are still lightly coupled. Eliminating this coupling is a task for a follow-up.
Migration Guide
Hierarchy and transform logic for colliders has been extracted from the
ColliderBackendPlugin
into a newColliderHierarchyPlugin
, which by default is included in thePhysicsPlugins
plugin group.If you are adding plugins manually, make sure you have both if you want that functionality.