World Position And Rotation After A Freeze

[eug]

I'm a newbie to MEL so sorry if it's a stupid question. I am trying to get transformation info from an object after it has been frozen. I noticed once Freeze Transformation is applied there is a new INPUT node on the mesh called "transformGeometry1." It has a 'transform' attribute that returned a matrix that had the correct position, but i don't think the rotation was correct.

Any help would be greatly appreciated.

Thanks,
Eugene

[joojaa]

QUOTE(Eugene E @ 07/21/06, 10:44 PM) [snapback]243049[/snapback]
I'm a newbie to MEL so sorry if it's a stupid question. I am trying to get transformation info from an object after it has been frozen.

Shouldnt this be prhased that you want the trasformation state of the object from before it was frozen? Because the idea of freezing is to kill all trasformations of the object and bring the matrix to full or partial identity thus it no longer has any connection to what it was before. If you happen to have hstory on its possible to deduce what it was tougfh PROWIDED you havent manipulated teh trasform wich makes sure the poinst stay in place.

If you seem to e doing alot of this think if freeze is actualy the tool you think it is. BAcause its actualy a heavy operation that affecs the precicion of your mesh. Offcourse after history flush its nolonger possible to go back.

Anyway to convert matrix to rotations is a bit tricky.

Firstof the internal maya uses radfians. Secondly the matrix does not store the angle directly its packed into it. Read:

http://www.euclideanspace.com/maths/geomet...Euler/index.htm

[rob-bateman]

I guess the answer you are after (depending on the options you set when freezing of course) is :

translate = 0,0,0
rotate = 0,0,0

If you don't want those values, then don't freeze the transforms

Having frozen the transforms, the only thing you can really do is describe an object with respect to a new co-ordinate frame (that you will need to define). Some people use the center of the object or it's pivot, some people use a 2nd defined transform, but that's your problem really (i.e. you told the transform to go away, so it is your fault it no longer exists, you can't get it back, so it's up to you to invent a new one for it - any transform you invent for it will not be the one that was used originally).

[ewerybody]

restoring a frozen rotation ?!? .. seems impossible to me. At least via automation. But there is a script called Local Tools from Henry Korol. With it you can turn the objects rotation to the rotation of a component or whatever else...

Restoring the actual translation depending on the pivot is easyer. If you move the pivot, freeze transformation or do a centerpivot maya does not update the actual position you see in the channel view at translate X, Y, Z... But it offsets the Local Rotate and Scale Pivot position. You can see this in the Attribute editor in the Pivots Frame.
A workaround is: You move the object to 0 0 0, take the "position", freeze again and apply the position inverted. (my resetPivot does this in one go ;] )

[failure]

Can I ask why exactly do you need to reconstruct euler angles? I mean once you have the matrix there's no need whatsoever to mess with eulers wich are btw just handy way for humans to fill in the matrix. Also note if you're going to reconstruct them anyway you'll need to know the xyz rotation order at the time of freezing. There's no way you can get this info from transformGeometry node. You can only asume. And without it your eulers might not match the original ones.

[eug]

Thanks for the responses. I guess I just won't worry about it. I am writing an export script for a gaming engine we're working on and just wanted to fool proof it.

Thanks again,
Eug

[ewerybody]

Yea I wrote the resetPivot for game engine export too. But meanwhile our exporter takes care of the Local Rotate and Scale Pivot position. But there are still issues at rotation animation we need to reset the pivot for.