Velocity And Vector

[madmikethespoon1]

Im not sure if this should go in here or in the MEL section so sorry if I'm wrong. Ok, I tried searching and couldnt find what I was looking for. Im trying to add attributes to an object that gives me vector and velocity of that object. I plan on using these attributes to control the orientation of an object using expressions. my question is how do I create these attributes. I am fairly new at writing expressions and creating attributes, however I have done simple things like creating an RPM (revolutions per minute) attribute. Any help on the subject would be great, thanx.

[joojaa]

only dynamics sim objects have velocity. mainly this applies to partilces. For everything else you need to calculate it yourself.

Just adding a attribute does nothing special.

[madmikethespoon1]

I understand that it is not natively calculated in maya, however I was either planning on creating an expression that did it using the position on my object at its current frame and subtracting its position at the previous frame. Or if there is an easier way, perhaps linking a particle to an object and using the velocity and vector of that particle. However I don

[joojaa]

QUOTE(madmikethes @ 12/12/07, 01:04 AM) [snapback]277930[/snapback]
I understand that it is not natively calculated in maya, however I was either planning on creating an expression that did it using the position on my object at its current frame and subtracting its position at the previous frame. Or if there is an easier way, perhaps linking a particle to an object and using the velocity and vector of that particle.

Drepends on what you find easier, use a cached global variable for the calc otherwise maya can get a abit slow if you have lots of theese objects.

Offcourse if you want you can create a derivate anim curve node.