prepare for 'custom' multi body creation.

examples/MultiBody/CustomMultiBodyCreationCallback.h

@@ -0,0 +1,42 @@
+#ifndef CUSTOM_MULTIBODY_CALLBACK_H
+#define CUSTOM_MULTIBODY_CALLBACK_H
+
+#ifdef USE_EIGEN
+	typedef Eigen::Quaternion<double> QuaternionType;
+	typedef Eigen::Vector3d<double> Vector3dType;
+	typedef double ScalarType;
+#else
+	typedef btQuaternion QuaternionType;
+	typedef btVector3 Vector3dType;
+	typedef btScalar	ScalarType;
+#endif
+
+class CustomMultiBodyCreationCallback
+{
+    
+public:
+
+	virtual ~CustomMultiBodyCreationCallback() {}
+
+    enum {
+        RevoluteJoint=1,
+        PrismaticJoint,
+        FixedJoint,
+    };
+ 
+    virtual int allocateMultiBodyBase(int urdfLinkIndex, int totalNumJoints,ScalarType baseMass, const Vector3dType& localInertiaDiagonal, bool isFixedBase) const =0;
+
+    virtual void addLinkAndJoint(int jointType, int linkIndex,            // 0 to num_links-1
+                       int parentIndex,
+                       double mass,
+                       const Vector3dType&	inertia,
+                       const QuaternionType &rotParentFrameToLinkFrame,  // rotate points in parent frame to this frame, when q = 0
+                       const Vector3dType&	jointAxisInLinkFrame,    // in Link frame
+                       const Vector3dType&	parentComToThisJointOffset,    // vector from parent COM to joint frame, in Parent frame
+                       const Vector3dType&	thisJointToThisComOffset) = 0;       // vector from joint frame to my COM, in Link frame);
+                 
+// @todo: Decide if we need this link mapping? 
+// virtual void addLinkMapping(int urdfLinkIndex, int mbLinkIndex) const = 0;
+};
+
+#endif //CUSTOM_MULTIBODY_CALLBACK_H