Collision callbacks for CannonJS

This will register an event callback for meshes that have the
onPhysicsCollide function set.

src/Physics/Plugins/babylon.cannonJSPlugin.js

@@ -54,12 +54,9 @@ var BABYLON;
             return value < BABYLON.PhysicsEngine.Epsilon ? BABYLON.PhysicsEngine.Epsilon : value;
         };
         CannonJSPlugin.prototype.runOneStep = function (delta) {
+            var _this = this;
             this._world.step(delta);
-            for (var index = 0; index < this._registeredMeshes.length; index++) {
-                var registeredMesh = this._registeredMeshes[index];
-                if (registeredMesh.isChild) {
-                    continue;
-                }
+            this._registeredMeshes.forEach(function (registeredMesh) {
                 // Body position
                 var bodyX = registeredMesh.body.position.x, bodyY = registeredMesh.body.position.y, bodyZ = registeredMesh.body.position.z;
                 registeredMesh.mesh.position.x = bodyX + registeredMesh.delta.x;
@@ -69,7 +66,27 @@ var BABYLON;
                 if (registeredMesh.deltaRotation) {
                     registeredMesh.mesh.rotationQuaternion.multiplyInPlace(registeredMesh.deltaRotation);
                 }
-            }
+                //is the physics collision callback is set?
+                if (registeredMesh.mesh.onPhysicsCollide) {
+                    if (!registeredMesh.collisionFunction) {
+                        registeredMesh.collisionFunction = function (e) {
+                            //find the mesh that collided with the registered mesh
+                            for (var idx = 0; idx < _this._registeredMeshes.length; idx++) {
+                                if (_this._registeredMeshes[idx].body == e.body) {
+                                    registeredMesh.mesh.onPhysicsCollide(_this._registeredMeshes[idx].mesh);
+                                }
+                            }
+                        };
+                        registeredMesh.body.addEventListener("collide", registeredMesh.collisionFunction);
+                    }
+                }
+                else {
+                    //unregister, in case the function was removed for some reason
+                    if (registeredMesh.collisionFunction) {
+                        registeredMesh.body.removeEventListener("collide", registeredMesh.collisionFunction);
+                    }
+                }
+            });
         };
         CannonJSPlugin.prototype.setGravity = function (gravity) {
             this._world.gravity.set(gravity.x, gravity.y, gravity.z);

src/Physics/Plugins/babylon.cannonJSPlugin.ts

@@ -1,10 +1,21 @@
 module BABYLON {
     declare var CANNON;
+    
+    interface IRegisteredMesh {
+        mesh: AbstractMesh;
+        body: any; //Cannon body
+        material : any;
+        delta: Vector3;
+        deltaRotation: Quaternion;
+        heightmap: boolean;
+        collisionFunction?: (event: any) => void;
+        
+    }
 
     export class CannonJSPlugin implements IPhysicsEnginePlugin {
 
         private _world: any;
-        private _registeredMeshes = [];
+        private _registeredMeshes : Array<IRegisteredMesh> = [];
         private _physicsMaterials = [];
 
         public initialize(iterations: number = 10): void {
@@ -20,12 +31,7 @@
         public runOneStep(delta: number): void {
             this._world.step(delta);
 
-            for (var index = 0; index < this._registeredMeshes.length; index++) {
-                var registeredMesh = this._registeredMeshes[index];
-
-                if (registeredMesh.isChild) {
-                    continue;
-                }
+            this._registeredMeshes.forEach((registeredMesh) => {
 
                 // Body position
                 var bodyX = registeredMesh.body.position.x,
@@ -40,7 +46,27 @@
                 if (registeredMesh.deltaRotation) {
                     registeredMesh.mesh.rotationQuaternion.multiplyInPlace(registeredMesh.deltaRotation);
                 }
-            }
+                
+                //is the physics collision callback is set?
+                if(registeredMesh.mesh.onPhysicsCollide) {
+                    if(!registeredMesh.collisionFunction) {
+                        registeredMesh.collisionFunction = (e) => {
+                            //find the mesh that collided with the registered mesh
+                            for (var idx = 0; idx < this._registeredMeshes.length; idx++) {
+                                if(this._registeredMeshes[idx].body == e.body) {
+                                    registeredMesh.mesh.onPhysicsCollide(this._registeredMeshes[idx].mesh);
+                                }
+                            }
+                        }
+                        registeredMesh.body.addEventListener("collide", registeredMesh.collisionFunction);
+                    }
+                } else {
+                    //unregister, in case the function was removed for some reason
+                    if(registeredMesh.collisionFunction) {
+                        registeredMesh.body.removeEventListener("collide", registeredMesh.collisionFunction)
+                    }
+                }
+            })
         }
 
         public setGravity(gravity: Vector3): void {