Expression ignoring Undo

[baalrog]

Got another question on these darn expressions.

My expression is moving some objects around every frame, making them follow particles. All of these transforms are recorded in the undo queue every frame. If I want to undo something once I've hit the play button, I have to hit Z a few hundred times.

Is there any way to disable the undo queue for the commands inside an expression, without clearing the queue before it?

I can work around not being able to undo, but it's really inconvenient. Any ideas would be much appreciated.

Thanks,
BaalRog

[joojaa]

Well it inte exactly meant that you use mel commands inside expressions use direct connections. If you give a fregment then maybe someone nice could convert it to a form thats mor intelligent.

And a LOT faster.

[baalrog]

vector $curpos = joint1joint3_pChildShape.position;

float $tempVector[];
$tempVector[0] = $curpos.x;
$tempVector[1] = $curpos.y;
$tempVector[2] = $curpos.z;

xform -ws -t $tempVector[0] $tempVector[1] $tempVector[2] joint1joint3_locChild;

The Expression just changes the child's (joint1joint3_locChild) position every frame. Every time the mel moves it around that move is saved in the undo buffer. I also have more than just one of these expressions running. The result is having to undo through every frame times the number of objects effected by the expression.

[joojaa]

Umm and whats the reason you cant use a constraint or parenting to do that?

[baalrog]

I can't parent or constrain anything to a particle's position, can I?

[joojaa]

No but you can feed the position of spesific particles to dummo objects in the same transform space as the perticle and constrain that... All inside the normal push and pull. If you do not adhere to the push and pull you might (or lets say unless you actualy undertand it very very well you will) cause a lot of extra overhead.

You can offcourse let the expression iterate the world position.

EDIT:
actualy i just realized it might be able feed particles to constraints kindoff.... If you do the connections manualy. Gotta taest this.

[baalrog]

Kickass, I'll try and play around with that too. My expressions are dog slow...but it's more of a post effect, so it's acceptable. I've tied in layer visibility to turn everything off when I need to get quick results.

What is this push and pull you speak of?