transform-invalidation.diff

commit acdae9ee7d92c7bfbbe2d560a3e00039ce5a3380
Author: Patrick Walton <pcwalton@mimiga.net>
Date:   Mon Feb 5 18:10:52 2024 -0800

    wip

diff --git a/crates/bevy_transform/Cargo.toml b/crates/bevy_transform/Cargo.toml
index 8e5e93718..cde746d06 100644
--- a/crates/bevy_transform/Cargo.toml
+++ b/crates/bevy_transform/Cargo.toml
@@ -19,6 +19,7 @@ bevy_math = { path = "../bevy_math", version = "0.12.0" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.12.0", features = [
   "bevy",
 ] }
+bevy_utils = { path = "../bevy_utils", version = "0.12.0" }
 serde = { version = "1", features = ["derive"], optional = true }
 thiserror = "1.0"
 
diff --git a/crates/bevy_transform/src/systems.rs b/crates/bevy_transform/src/systems.rs
index 8f6bac916..d5365b944 100644
--- a/crates/bevy_transform/src/systems.rs
+++ b/crates/bevy_transform/src/systems.rs
@@ -7,6 +7,7 @@ use bevy_ecs::{
     system::{Local, ParamSet},
 };
 use bevy_hierarchy::{Children, Parent};
+use bevy_utils::EntityHashSet;
 
 /// Update [`GlobalTransform`] component of entities that aren't in the hierarchy
 ///
@@ -54,19 +55,41 @@ pub fn propagate_transforms(
     mut orphaned: RemovedComponents<Parent>,
     transform_query: Query<(Ref<Transform>, &mut GlobalTransform, Option<&Children>), With<Parent>>,
     parent_query: Query<(Entity, Ref<Parent>)>,
+    dirty_roots: Query<Entity, Or<(Changed<Parent>, Changed<Transform>)>>,
     mut orphaned_entities: Local<Vec<Entity>>,
 ) {
     orphaned_entities.clear();
     orphaned_entities.extend(orphaned.read());
     orphaned_entities.sort_unstable();
+
+    let mut dirty_entities = EntityHashSet::default();
+    for mut current in dirty_roots.iter() {
+        while dirty_entities.insert(current) {
+            let Ok((parent, _)) = parent_query.get(current) else {
+                break;
+            };
+            current = parent;
+        }
+    }
+
     root_query.par_iter_mut().for_each(
         |(entity, children, transform, mut global_transform)| {
+            // If this entire tree is clean, do nothing.
+            if !dirty_entities.contains(&entity) {
+                return;
+            }
+
             let changed = transform.is_changed() || global_transform.is_added() || orphaned_entities.binary_search(&entity).is_ok();
             if changed {
                 *global_transform = GlobalTransform::from(*transform);
             }
 
             for (child, actual_parent) in parent_query.iter_many(children) {
+                // Don't bother checking children if we know their transform didn't change.
+                if !changed && !dirty_entities.contains(&child) {
+                    continue;
+                }
+
                 assert_eq!(
                     actual_parent.get(), entity,
                     "Malformed hierarchy. This probably means that your hierarchy has been improperly maintained, or contains a cycle"
@@ -84,6 +107,7 @@ pub fn propagate_transforms(
                         &global_transform,
                         &transform_query,
                         &parent_query,
+                        &dirty_entities,
                         child,
                         changed || actual_parent.is_changed(),
                     );
@@ -113,6 +137,7 @@ unsafe fn propagate_recursive(
         With<Parent>,
     >,
     parent_query: &Query<(Entity, Ref<Parent>)>,
+    dirty_entities: &EntityHashSet<Entity>,
     entity: Entity,
     mut changed: bool,
 ) {
@@ -157,6 +182,11 @@ unsafe fn propagate_recursive(
 
     let Some(children) = children else { return };
     for (child, actual_parent) in parent_query.iter_many(children) {
+        // Don't bother checking children if we know their transform didn't change.
+        if !changed && !dirty_entities.contains(&child) {
+            continue;
+        }
+
         assert_eq!(
             actual_parent.get(), entity,
             "Malformed hierarchy. This probably means that your hierarchy has been improperly maintained, or contains a cycle"
@@ -171,6 +201,7 @@ unsafe fn propagate_recursive(
                 &global_matrix,
                 transform_query,
                 parent_query,
+                dirty_entities,
                 child,
                 changed || actual_parent.is_changed(),
             );
diff --git a/examples/tools/scene_viewer/main.rs b/examples/tools/scene_viewer/main.rs
index e80b3965b..3ef3f739b 100644
--- a/examples/tools/scene_viewer/main.rs
+++ b/examples/tools/scene_viewer/main.rs
@@ -8,6 +8,7 @@
 //! If you want to hot reload asset changes, enable the `file_watcher` cargo feature.
 
 use bevy::{
+    diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
     math::Vec3A,
     prelude::*,
     render::primitives::{Aabb, Sphere},
@@ -44,6 +45,8 @@ fn main() {
         CameraControllerPlugin,
         SceneViewerPlugin,
         MorphViewerPlugin,
+        FrameTimeDiagnosticsPlugin,
+        LogDiagnosticsPlugin::default(),
     ))
     .add_systems(Startup, setup)
     .add_systems(PreUpdate, setup_scene_after_load);