Improve the API for initializing/setting mass-properties

2 files changed, 24 insertions, 22 deletions

diff --git a/src/pipeline/physics_pipeline.rs b/src/pipeline/physics_pipeline.rs
index d347637..71ab578 100644
--- a/src/pipeline/physics_pipeline.rs
+++ b/src/pipeline/physics_pipeline.rs
@@ -407,6 +407,9 @@ impl PhysicsPipeline {
         hooks: &dyn PhysicsHooks,
         events: &dyn EventHandler,
     ) {
+        self.counters.reset();
+        self.counters.step_started();
+
         // Apply some of delayed wake-ups.
         for handle in impulse_joints
             .to_wake_up
@@ -417,18 +420,15 @@ impl PhysicsPipeline {
         }
 
         // Apply modifications.
-        let modified_bodies = bodies.take_modified();
         let mut modified_colliders = colliders.take_modified();
         let mut removed_colliders = colliders.take_removed();
-
-        self.counters.reset();
-        self.counters.step_started();
-
         super::user_changes::handle_user_changes_to_colliders(
             bodies,
             colliders,
             &modified_colliders[..],
         );
+
+        let modified_bodies = bodies.take_modified();
         super::user_changes::handle_user_changes_to_rigid_bodies(
             Some(islands),
             bodies,
diff --git a/src/pipeline/user_changes.rs b/src/pipeline/user_changes.rs
index 9872208..e7da68a 100644
--- a/src/pipeline/user_changes.rs
+++ b/src/pipeline/user_changes.rs
@@ -2,17 +2,12 @@ use crate::dynamics::{
     IslandManager, RigidBodyChanges, RigidBodyHandle, RigidBodySet, RigidBodyType,
 };
 use crate::geometry::{ColliderChanges, ColliderHandle, ColliderPosition, ColliderSet};
-use parry::utils::hashmap::HashMap;
 
 pub(crate) fn handle_user_changes_to_colliders(
     bodies: &mut RigidBodySet,
     colliders: &mut ColliderSet,
     modified_colliders: &[ColliderHandle],
 ) {
-    // TODO: avoid this hashmap? We could perhaps add a new flag to RigidBodyChanges to
-    //       indicated that the mass properties need to be recomputed?
-    let mut mprops_to_update = HashMap::default();
-
     for handle in modified_colliders {
         // NOTE: we use `get` because the collider may no longer
         //       exist if it has been removed.
@@ -26,22 +21,19 @@ pub(crate) fn handle_user_changes_to_colliders(
                 }
             }
 
-            if co.changes.contains(ColliderChanges::SHAPE) {
-                if let Some(co_parent) = co.parent {
-                    mprops_to_update.insert(co_parent.handle, ());
+            if co
+                .changes
+                .intersects(ColliderChanges::SHAPE | ColliderChanges::LOCAL_MASS_PROPERTIES)
+            {
+                if let Some(rb) = co
+                    .parent
+                    .and_then(|p| bodies.get_mut_internal_with_modification_tracking(p.handle))
+                {
+                    rb.changes |= RigidBodyChanges::LOCAL_MASS_PROPERTIES;
                 }
             }
         }
     }
-
-    for (to_update, _) in mprops_to_update {
-        let rb = bodies.index_mut_internal(to_update);
-        rb.mprops.recompute_mass_properties_from_colliders(
-            colliders,
-            &rb.colliders,
-            &rb.pos.position,
-        );
-    }
 }
 
 pub(crate) fn handle_user_changes_to_rigid_bodies(
@@ -163,6 +155,16 @@ pub(crate) fn handle_user_changes_to_rigid_bodies(
                 }
             }
 
+            if changes
+                .intersects(RigidBodyChanges::LOCAL_MASS_PROPERTIES | RigidBodyChanges::COLLIDERS)
+            {
+                rb.mprops.recompute_mass_properties_from_colliders(
+                    colliders,
+                    &rb.colliders,
+                    &rb.pos.position,
+                );
+            }
+
             rb.changes = RigidBodyChanges::empty();
             rb.ids = ids;
             rb.activation = activation;