evalAtFrame() and chop constraints weirdness

[jordibares]

I am writing a little python tool that requires evaluating the value of a channel a particular frame, but the object i am evaluating has a chop constraint and the function

        pos = internal_cam.parmTuple('t').evalAtFrame(f)

returns (0,0,0)

I imagine the chop network is "overriding" the value but I don't seem to get the result.

Any ideas?

Thanks.

jb

[symek]

i think it's not related to constraints nor chops per se. evalParm() is 'conservative' in a sense it doesn't obey higher order operation (as parenting or constraining), just giving raw channel values. Albeit this line:

hou.node(...).worldTransformAtTime(frame).extractTranslates()

gives the definite position whenever parented, constrained and what's not happening with a node.

[jordibares]

Thanks Szymon, I did end up using that approach and it works well, nevertheless it has been quite annoying not to be able to rely on the evalAtFrame()

I took advantage as well as the worldTransformAtTime does a proper evaluation on the frame so I don't need to update the frame and things are a lot faster and smoother.

 

Thanks once again.