I want to animate an object's position based on input from the user's mouse wheel. The mouse wheel can fire events many times per second. I don't want to destroy the old animation, and create a new one, for each of these many events. I'd prefer to "update" the keyframes of the existing animation instead (i.e. continue the animation from its current frame and position, to a new endPosition at a new keyframe). I'd also like to "restart" the animation again from its current value, if it happens to reach the final keyframe and stop, then the user scrolls again later.