grasp object over a predefined path.

Hi,

I'm using Leapmotion to grasp an object. It must follow a predefined path. So there's a start position and an end position. When grasping begins, the distance between start position and current position is the current distance. When grasping if activated, I store the begin values. After that I define whats the distance and the angle. But my solution doesn't work, because an negative angles is not equal to a negative distance.

             float grasp_distance = Vector3.Distance(beginGraspPoint, graspPoint);
 
             float grasp_angle = Vector3.Angle(beginObjectPosition, graspPoint);
             float curr_grasp_obj_angle = Vector3.Angle(beginObjectPosition, graspPoint);
             float diff_grasp_obj_angle = curr_grasp_obj_angle - grasp_obj_angle;

             
             if (diff_grasp_obj_angle < 0)
                 grasp_distance = -grasp_distance;
            
             float s = getSmoothGrasp(grasp_distance + beginDistance);
 
             float maxDistance = Vector3.Distance(m_EndPosition, m_StartPosition);
             float obj_angle = Vector3.Angle(m_EndPosition, m_StartPosition);
             float t = (s) / maxDistance;
             this.gameObject.transform.position = Vector3.Lerp(m_StartPosition, m_EndPosition, Mathf.SmoothStep(0.0f, 1.0f, t));
 
             lastDistance = s; // this becomes beginDistance

I was wondering what is the best option to make this working?