- PointForceController now has "setTrackedObject()" and "getTrackedObject()" to force it to track that SceneObjects' position. When tracking an object, the "setPosition()" is used as a tracked-object local-space offset i.e. a position of (0,0) is at the tracked objects center but (1,0) is 1 world-unit along the objects local-space X-axis (including angle).

engine/source/2d/controllers/PointForceController.cc

@@ -86,6 +86,14 @@ void PointForceController::copyTo(SimObject* object)
 
 //------------------------------------------------------------------------------
 
+void PointForceController::setTrackedObject( SceneObject* pSceneObject )
+{
+    // Set tracked object.
+    mTrackedObject = pSceneObject;
+}
+
+//------------------------------------------------------------------------------
+
 void PointForceController::integrate( Scene* pScene, const F32 totalTime, const F32 elapsedTime, DebugStats* pDebugStats )
 {
     // Finish if the attractor would have no effect.
@@ -95,10 +103,13 @@ void PointForceController::integrate( Scene* pScene, const F32 totalTime, const
     // Prepare query filter.
     WorldQuery* pWorldQuery = prepareQueryFilter( pScene );
 
+    // Fetch the current position.
+    const Vector2 currentPosition = getCurrentPosition();
+
     // Calculate the AABB of the attractor.
     b2AABB aabb;
-    aabb.lowerBound.Set( mPosition.x - mRadius, mPosition.y - mRadius );
-    aabb.upperBound.Set( mPosition.x + mRadius, mPosition.y + mRadius );
+    aabb.lowerBound.Set( currentPosition.x - mRadius, currentPosition.y - mRadius );
+    aabb.upperBound.Set( currentPosition.x + mRadius, currentPosition.y + mRadius );
 
     // Query for candidate objects.
     pWorldQuery->anyQueryArea( aabb ); 
@@ -123,18 +134,25 @@ void PointForceController::integrate( Scene* pScene, const F32 totalTime, const
     const F32 linearDrag = mClampF( mLinearDrag, 0.0f, 1.0f ) * elapsedTime;
     const F32 angularDrag = mClampF( mAngularDrag, 0.0f, 1.0f ) * elapsedTime;
 
+    // Fetch the tracked object.
+    const SceneObject* pTrackedObject = mTrackedObject;
+
     // Iterate the results.
     for ( U32 n = 0; n < resultCount; n++ )
     {
         // Fetch the scene object.
         SceneObject* pSceneObject = queryResults[n].mpSceneObject;
 
+        // Ignore if it's the tracked object.
+        if ( pSceneObject == pTrackedObject )
+            continue;
+
         // Ignore if it's a static body.
         if ( pSceneObject->getBodyType() == b2_staticBody )
             continue;
 
-        // Calculate the force distance to the controllers position.
-        Vector2 distanceForce = mPosition - pSceneObject->getPosition();
+        // Calculate the force distance to the controllers current position.
+        Vector2 distanceForce = currentPosition - pSceneObject->getPosition();
 
         // Skip if the position is outside the radius.
         if ( distanceForce.LengthSquared() > radiusSqr )
@@ -191,5 +209,5 @@ void PointForceController::renderOverlay( Scene* pScene, const SceneRenderState*
     Parent::renderOverlay( pScene, pSceneRenderState, pBatchRenderer );
 
     // Draw force radius.
-    pScene->mDebugDraw.DrawCircle( mPosition, mRadius, ColorF(1.0f, 1.0f, 0.0f ) );
+    pScene->mDebugDraw.DrawCircle( getCurrentPosition(), mRadius, ColorF(1.0f, 1.0f, 0.0f ) );
 }

engine/source/2d/controllers/PointForceController.h

@@ -56,6 +56,9 @@ private:
 	/// Linear drag co-efficient.
 	F32 mAngularDrag;
 
+    /// Tracked object.
+    SimObjectPtr<SceneObject> mTrackedObject;
+
 public:
     PointForceController();
     virtual ~PointForceController();
@@ -75,6 +78,16 @@ public:
     inline F32 getLinearDrag( void ) const { return mLinearDrag; }
     inline void setAngularDrag( const F32 angularDrag ) { mAngularDrag = angularDrag; }
     inline F32 getAngularDrag( void ) const { return mAngularDrag; }
+    void setTrackedObject( SceneObject* pSceneObject );
+    inline SceneObject* getTrackedObject( void ) { return mTrackedObject; }
+    inline Vector2 getCurrentPosition( void )
+    {
+        // Fetch the tracked object.
+        SceneObject* pSceneObject = mTrackedObject;
+
+        // Return the controller position if no tracked object else the tracked object position plus a tracked object local-space position.
+        return pSceneObject == NULL ? mPosition : b2Mul( pSceneObject->getTransform(), mPosition);
+    }
 
     /// Integration.
     virtual void integrate( Scene* pScene, const F32 totalTime, const F32 elapsedTime, DebugStats* pDebugStats );

engine/source/2d/controllers/PointForceController_ScriptBinding.h

@@ -144,3 +144,26 @@ ConsoleMethod(PointForceController, getNonLinear, bool, 2, 2,  "() Gets whether
     return object->getNonLinear();
 }
 
+//-----------------------------------------------------------------------------
+
+ConsoleMethod(PointForceController, setTrackedObject, void, 3, 3,   "(sceneObject) - Sets a scene object from which the position will be tracked.\n"
+                                                                    "@param sceneObject The scene object from which the position will be tracked.  An empty string will stop tracking.\n"
+                                                                    "@return No return value.")
+{
+    // Find the scene object.
+    SceneObject* pSceneObject = Sim::findObject<SceneObject>( argv[2] );
+
+    object->setTrackedObject( pSceneObject );
+} 
+
+//-----------------------------------------------------------------------------
+
+ConsoleMethod(PointForceController, getTrackedObject, const char*, 2, 2,    "() - Gets the scene object from which the position will be tracked.\n"
+                                                                            "@return The scene object from which the position will be tracked or an empty string if nothing is being tracked.")
+{
+    // Fetch the scene object.
+    SceneObject* pSceneObject = object->getTrackedObject();
+
+    return pSceneObject == NULL ? NULL : pSceneObject->getIdString();
+} 
+