View Full Version : motion designer rotation

04-07-2003, 01:51 PM
Hi, also new to the boards :). I have a question which i cant seem to get answered anywhere else, or better yet find out on my own.

Ill just use the same question as before.. here goes.

I have a scene with a soccer ball and a floor set up (simple objects for testing). Im using motionDesigner to get the ball bouncing around properly but the problem im running into is that lw keeps the ball straight and not rotating. Normaly if you throw a ball, once it hits the ground, provided that the ground and ball both have any sort of friction (and both do), it should cause the ball to start rotating but im unable to get it to do so. Even when i "give it a push" I.e. start the rotation through keyframes, like i do the initial throw, it doesnt carry out.

Aditionally, where do i specify when motion designer should take over? For ex, frames 1-10 are the throw sequence, then motion designer starts calculating.

I hope i can get some support on this. The ball is simple geometry as is the floor. It bonces right and looks rigid and all but it just does not rotate upon hitting the floor for the first time.

To get it to move i setup a few frames for a "throw" part and even though MD starts calculating right away it does carry out the "throw"'s motion, but not the rotation.

Thanks in advance.. again!

04-08-2003, 01:15 PM
Sounds like you'll need to get the keyframes that correspond to each bounce event, and then create the desired rotations for each interval between bounces. You could use expressions on the rotation with a step function at each bounce.

If you want a physically realistic response to the frictional torque imparted by the floor-ball interaction (true simulation) I'm not sure how to go about that, or even if LW can do it.

04-09-2003, 09:01 AM
hmm, i guess im not really following becuse i was under the impresion that when md starts calculating, it overwrites the keyframing that happens afterwards. I will try it with the expression however and see what that gets me.

True rotation is not really important as much as the true "look" of the ball, which in my case is not a ball but more of a jello like object which md brings to life. This is the reason i chose it in the first place. Otherwise id settle with gravity and keyframing rotation.

Thanks a lot for the reply.