Hi,
I noticed a weird behavior when trying to scale a constraint object.
My setup is made of 3 elements. One parent and its child, and a null, at
the same level as parent. parent and null are aimConstraining the child (so
the child will follow .5 each)
parent
|__ child
null
The weirdness happens when combining rotation and scale, which introduces
some shear effect.. what I can't figure out though, is why this shear is
affecting so much the rotation (my vectors are still visible as
perpendicular).
To check by yourself, you can run this snippet :
parent = cmds.createNode('transform', ss=1)
cube = cmds.polyCube()[0]
cmds.parent(cube, parent, r=1)
null = cmds.createNode('transform', ss=1)
cmds.orientConstraint(parent, null, cube, mo=0)
cmds.setAttr(parent + '.rx', 45)
print 'before scale / shear', cmds.getAttr(cube + '.rx')
cmds.setAttr(parent + '.sy', 2)
print 'after scale / shear', cmds.getAttr(cube + '.rx')
Before scaling, the rotateX of my cube is correct, but after, it's like
40-is degrees, which doesn't make much sense to me....
I have a shitty fix (run this code)
# shittyFix
dcm = cmds.createNode('decomposeMatrix', ss=1)
cmds.connectAttr(cube + '.wm', dcm + '.inputMatrix')
cpm = cmds.createNode('composeMatrix', ss=1)
cmds.connectAttr(dcm + '.or', cpm + '.ir')
cmds.connectAttr(dcm + '.os', cpm + '.is')
cmds.connectAttr(dcm + '.ot', cpm + '.it')
outDcm = cmds.createNode('decomposeMatrix', ss=1)
cmds.connectAttr(cpm + '.outputMatrix', outDcm + '.inputMatrix')
outLoc = cmds.spaceLocator()[0]
cmds.connectAttr(outDcm + '.orx', outLoc + '.rx')
print 'after shitty fix', cmds.getAttr(outLoc + '.rx')
but it's still not perfect, and I'm not sur why... could this be due to
some round issue ? That looks too much to me...
Does anyone have an idea on how to get my proper pCube.rx = 22.5, with this
setup (i.e. compensate the shear) ??
Thanks a lot !
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