Hello,

I’m stuck while trying to obtain what should to be a very straightforward procedure during the import of a FBX file. I’m looping through my curve keys to get the tangent angles to the left and right of it.

As an example, using

gives me a value of 88.07 which is about 89.34 degrees. This cannot be correct as the curve is not that steep. For your reference this key is defined as KFCURVE_INTERPOLATION_CUBIC, KFCURVE_TANGEANT_BREAK, KFCURVE_VELOCITY_NONE, KFCURVE_WEIGHTED_NONE.

If I import my FBX file into Maya and go to:
Graph Editor, Curves, Spreedsheet
I can see that for the same key the “InTan Angle” is 74.75 degrees which is more likely.

So my questions are:
a) What exactly KeyGetLeftDerivative is returning?
b) How the Maya Importer obtain the correct results?

Thanks

You have to divide that value by the frame rate. For example, in Maya, the default frame rate is 24.
88.07 / 24 = 3.67, corresponding to an angle of 74.75 degrees.

Viviane

Viviane Rochon
Maya Data Platform
Autodesk