Implement Clone for everything that can be cloned.

src/data/maybe_serializable_data.rs

@@ -9,6 +9,9 @@ pub trait MaybeSerializableData: DowncastSync {
     fn as_serialize(&self) -> Option<(u32, &dyn Serialize)> {
         None
     }
+
+    /// Clones `self`.
+    fn clone_dyn(&self) -> Box<dyn MaybeSerializableData>;
 }
 
 impl_downcast!(sync MaybeSerializableData);

src/data/pubsub.rs

@@ -5,6 +5,7 @@ use std::marker::PhantomData;
 
 /// A permanent subscription to a pub-sub queue.
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct Subscription<T> {
     // Position on the cursor array.
     id: u32,
@@ -12,6 +13,7 @@ pub struct Subscription<T> {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 struct PubSubCursor {
     // Position on the offset array.
     id: u32,
@@ -36,6 +38,7 @@ impl PubSubCursor {
 
 /// A pub-sub queue.
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct PubSub<T> {
     deleted_messages: u32,
     deleted_offsets: u32,

src/dynamics/rigid_body_set.rs

@@ -75,6 +75,7 @@ impl BodyPair {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 /// A set of rigid bodies that can be handled by a physics pipeline.
 pub struct RigidBodySet {
     // NOTE: the pub(crate) are needed by the broad phase

src/geometry/broad_phase_multi_sap.rs

@@ -132,6 +132,7 @@ impl Endpoint {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 struct SAPAxis {
     min_bound: f32,
     max_bound: f32,
@@ -331,6 +332,7 @@ impl SAPAxis {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 struct SAPRegion {
     axes: [SAPAxis; DIM],
     existing_proxies: BitVec,
@@ -411,6 +413,7 @@ impl SAPRegion {
 
 /// A broad-phase based on multiple Sweep-and-Prune instances running of disjoint region of the 3D world.
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct BroadPhase {
     proxies: Proxies,
     regions: HashMap<Point<i32>, SAPRegion>,
@@ -438,6 +441,7 @@ pub struct BroadPhase {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub(crate) struct BroadPhaseProxy {
     handle: ColliderHandle,
     aabb: AABB<f32>,
@@ -445,6 +449,7 @@ pub(crate) struct BroadPhaseProxy {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 struct Proxies {
     elements: Vec<BroadPhaseProxy>,
     first_free: u32,

src/geometry/collider_set.rs

@@ -17,6 +17,7 @@ pub(crate) struct RemovedCollider {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 /// A set of colliders that can be handled by a physics `World`.
 pub struct ColliderSet {
     pub(crate) removed_colliders: PubSub<RemovedCollider>,

src/geometry/contact.rs

@@ -172,6 +172,7 @@ impl Contact {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 /// The description of all the contacts between a pair of colliders.
 pub struct ContactPair {
     /// The pair of colliders involved.

src/geometry/contact_generator/contact_generator_workspace.rs

@@ -9,6 +9,12 @@ use crate::geometry::contact_generator::{
 // Note we have this newtype because it simplifies the serialization/deserialization code.
 pub struct ContactGeneratorWorkspace(pub Box<dyn MaybeSerializableData>);
 
+impl Clone for ContactGeneratorWorkspace {
+    fn clone(&self) -> Self {
+        ContactGeneratorWorkspace(self.0.clone_dyn())
+    }
+}
+
 impl<T: MaybeSerializableData> From<T> for ContactGeneratorWorkspace {
     fn from(data: T) -> Self {
         Self(Box::new(data) as Box<dyn MaybeSerializableData>)

src/geometry/contact_generator/heightfield_shape_contact_generator.rs

@@ -12,6 +12,7 @@ use crate::ncollide::bounding_volume::BoundingVolume;
 use erased_serde::Serialize;
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 struct SubDetector {
     #[cfg_attr(feature = "serde-serialize", serde(skip))]
     generator: Option<PrimitiveContactGenerator>,
@@ -21,6 +22,7 @@ struct SubDetector {
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct HeightFieldShapeContactGeneratorWorkspace {
     timestamp: bool,
     #[cfg_attr(feature = "serde-serialize", serde(skip))]
@@ -182,4 +184,8 @@ impl MaybeSerializableData for HeightFieldShapeContactGeneratorWorkspace {
             self,
         ))
     }
+
+    fn clone_dyn(&self) -> Box<dyn MaybeSerializableData> {
+        Box::new(self.clone())
+    }
 }

src/geometry/contact_generator/pfm_pfm_contact_generator.rs

@@ -9,6 +9,7 @@ use ncollide::query;
 use ncollide::query::algorithms::{gjk::GJKResult, VoronoiSimplex};
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct PfmPfmContactManifoldGeneratorWorkspace {
     #[cfg_attr(
         feature = "serde-serialize",
@@ -136,4 +137,8 @@ impl MaybeSerializableData for PfmPfmContactManifoldGeneratorWorkspace {
             self,
         ))
     }
+
+    fn clone(&self) -> Box<MaybeSerializableData> {
+        Box::new(self.clone())
+    }
 }

src/geometry/contact_generator/trimesh_shape_contact_generator.rs

@@ -8,6 +8,7 @@ use crate::ncollide::bounding_volume::{BoundingVolume, AABB};
 use erased_serde::Serialize;
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct TrimeshShapeContactGeneratorWorkspace {
     interferences: Vec<usize>,
     local_aabb2: AABB<f32>,
@@ -213,4 +214,8 @@ impl MaybeSerializableData for TrimeshShapeContactGeneratorWorkspace {
             self,
         ))
     }
+
+    fn clone_dyn(&self) -> Box<dyn MaybeSerializableData> {
+        Box::new(self.clone())
+    }
 }

src/geometry/interaction_graph.rs

@@ -10,6 +10,7 @@ pub type TemporaryInteractionIndex = EdgeIndex;
 
 /// A graph where nodes are collision objects and edges are contact or proximity algorithms.
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct InteractionGraph<T> {
     pub(crate) graph: Graph<ColliderHandle, T>,
 }

src/geometry/narrow_phase.rs

@@ -29,6 +29,7 @@ use std::collections::HashMap;
 
 /// The narrow-phase responsible for computing precise contact information between colliders.
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct NarrowPhase {
     contact_graph: InteractionGraph<ContactPair>,
     proximity_graph: InteractionGraph<ProximityPair>,

src/geometry/proximity.rs

@@ -15,6 +15,18 @@ pub struct ProximityPair {
     pub(crate) detector_workspace: Option<Box<dyn Any + Send + Sync>>,
 }
 
+// TODO: use the `derive(Clone)` instead?
+impl Clone for ProximityPair {
+    fn clone(&self) -> Self {
+        ProximityPair {
+            pair: self.pair.clone(),
+            proximity: self.proximity.clone(),
+            detector: None,
+            detector_workspace: None,
+        }
+    }
+}
+
 impl ProximityPair {
     pub(crate) fn new(
         pair: ColliderPair,

src/pipeline/query_pipeline.rs

@@ -5,6 +5,7 @@ use crate::geometry::{
 
 /// A pipeline for performing queries on all the colliders of a scene.
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+#[derive(Clone)]
 pub struct QueryPipeline {
     quadtree: WQuadtree<ColliderHandle>,
     tree_built: bool,