Create a mirror object method

[puppetsoul]

Hi all, I try to write a mirror object method. This should :

• work in tranlsation and rotation
• work in local and world
• care about freeze transformation and joint orient
• be able to mirror from woerld center, but also a user object (who moves in Tr AND ro!)

I know that maya 2014 have a symetry constraint, but this one is incomplete (now rotation on the mirror object from what I see)

I'm quiet new to matrix, and vector. I succed to do the mirror through world on usual object...
My method is : 

• extract worldMatrix from source object (sourceWorldMatrix)
• extract inverseWorldMatrix from root mirro object.(rootInvWorldMatrix)
• do :  sourceWorldMatrix = sourceWorldMatrix * rootInvWorldMatrix
• and REDO   sourceWorldMatrix = sourceWorldMatrix * rootInvWorldMatrix  . Why it does work if I multiply twice????
• extract vector then transation
• for the vectors : If I want to mirror in X, I inverse the X of all vectors
• the I inverse the x vector itself ot became consistent
• from the destinaton, get the destParentInvMatrix
• mirroredMatrix = mirroredMatrix * destParentInvMatrix
• extract from mirroredMatrix the roation in euler and done! 

How can I :
Care about the pivot/jointOrient, care about the root center mirror object?  

Thanks a lot.  

[joojaa]

rootInvWorldMatrix  . Why it does work if I multiply twice????

Show us the matrix and the original matrix of a simple case.

Anyway mirroring is very easy in terms of matrix math, there is just so many things that need to be considered. First winding order changes so uvs and faces are now wrong way around. Custom normals need to be transformed with the inverse of the transpose (if i remember correctly). Etc etc list goes on and on. Second you don't actually want to scale the transforms to mirror them. Rather you should construct the same matrix out of something thats positioned on a mirrored point but the same way as the original, only pointing 2 directions the new way. Determining which direction should not flip is a bit problematic (except tin cardinal axes).

So for me it seems that doing the mirror function so it satisfies all possible cases is very hard work. Even then you end up with something that just satisfies your need. Others would consider some different interpretation correct. Which means you can not really win. Besides this does not fix the real roblem that the selection mirroring is broken.

[puppetsoul]

Hi Joojaa.. Thanks for your answer.

Actually I don't care about Mesh or UVs, because I want to write a animation tool : be able to mirror/swap transforms, and so on, poses.

Car about local transformation is easy. But I want to be able also to mirror it in workd space, regardless to a user object (root of a spine for instance)

Later on my rig, I will tag object to know if they are express primaru in local (FK parts) or world (IK part).
All is almost done. Just miss this world mirror stuff ....

Any idea?