Follow and Look At with RTRE

It is possible to use Follow Path and Look At constraints with RTRE, but there is a trick you need to use to make it work.

It is possible to use Follow Path and Look At constraints with RTRE, but there is a trick you need to use to make it work.

Follow Path and Look At

This animation uses Follow Path, and LookAt to have the red cone follow the path while looking at the central sphere. The path has been duplicated and then rendered as a mesh so that it is visible. Also a second cone was linked to the first cone so that its orientation can be seen as it follows the path.

The moving rods and pistons show another use of LookAt. The horizontal rods are animated to move back and forth. The balls and pistons [just nested cyllinders] are linked to follow the rods. The wide part of the piston is looking at the the ball, and the inner piston is looking at the outer piston. In max, both sets of pistons behave the same, but in RTRE, the red piston fails to behave correctly. Note that it is not possible to have two objects look at each other, so another object, the ball, is required to complete the circuit.

To fix the blue piston in RTRE, it is quite simple. One merely has to add some dummy keyframes to cause RTRE to pickup the animation of the objects as they are transformed by max. To do this, add a position keyframe to the first and last frame. The look at constraints are rotational constraints, so this does not conflict with a position key. But the position keys cause RTRE to pickup the entire transform for the object, including the rotation, so the look at constraint is correctly animated by RTRE.

Download the FollowPath Scene