Fix user-change handling for colliders as well as disabled colliders (#900)

* feat: add debug-demo for disabling a collider

* feat: add a simple debug-demo with two cubes

* feat: rename RigidBodyChangnes::MODIFIED and ColliderChanges::MODIFIED to ::IN_MODIFIED_SET

* feat: render debug-colliders with a different color with the debug-renderer

* chore: wire up new examples to the testbed

* fix colliders user-modification being ignored after the first step

* fix broad-phase still taking into account disabled colliders with enabled dynamic rigid-bodies

* chore: update changelog

* fix cargo doc

src/geometry/broad_phase_bvh.rs

@@ -69,10 +69,6 @@ impl BroadPhaseBvh {
     /// sent previously and no `RemovePair` happened since then). Sending redundant events is allowed
     /// but can result in a slight computational overhead.
     ///
-    /// The `colliders` set is mutable only to provide access to
-    /// [`collider.set_internal_broad_phase_proxy_index`]. Other properties of the collider should
-    /// **not** be modified during the broad-phase update.
-    ///
     /// # Parameters
     /// - `params`: the integration parameters governing the simulation.
     /// - `colliders`: the set of colliders. Change detection with `collider.needs_broad_phase_update()`

src/geometry/collider_components.rs

@@ -35,8 +35,8 @@ bitflags::bitflags! {
     #[derive(Copy, Clone, PartialEq, Eq, Debug)]
     /// Flags describing how the collider has been modified by the user.
     pub struct ColliderChanges: u32 {
-        /// Flag indicating that any component of the collider has been modified.
-        const MODIFIED = 1 << 0;
+        /// Flag indicating that the collider handle is in the changed collider set.
+        const IN_MODIFIED_SET = 1 << 0;
         /// Flag indicating that the density or mass-properties of this collider was changed.
         const LOCAL_MASS_PROPERTIES = 1 << 1; // => RigidBody local mass-properties update.
         /// Flag indicating that the `ColliderParent` component of the collider has been modified.

src/geometry/collider_set.rs

@@ -11,12 +11,12 @@ pub type ModifiedColliders = ModifiedObjects<ColliderHandle, Collider>;
 impl HasModifiedFlag for Collider {
     #[inline]
     fn has_modified_flag(&self) -> bool {
-        self.changes.contains(ColliderChanges::MODIFIED)
+        self.changes.contains(ColliderChanges::IN_MODIFIED_SET)
     }
 
     #[inline]
     fn set_modified_flag(&mut self) {
-        self.changes |= ColliderChanges::MODIFIED;
+        self.changes |= ColliderChanges::IN_MODIFIED_SET;
     }
 }