What's the exact definition of rotation order in FBX SDK?

[shuang1978]

Hi guys,

I'm trying to import animation from FBX into our in-house game engine. Our engine can deal with different rotation orders and pre-rotation. So I can keep that info unchanged when importing.

My question is quite simple:

1. How does FBX SDK define rotation order? Is it by intrinsic rotation or extrinsic rotation? Say if I have rotation angles X, Y, Z. And I have rotation matrices around each axis as Mx, My, Mz. Now if I choose rotation order eEulerXYZ, should the final rotation matrix be as Mz * My * Mx or as Mx * My * Mz?

2. What's the rotation order for PreRotation? I mean the definition of angles in FbxNode::PreRotation. Is it using a fixed rotation order or just the same as FbxNode::RotationOrder?

Thanks in advance.

[L-Spiro]

#1: The matrices in the Autodesk® FBX® SDK are in column-major, and thus combined in reverse ZYX order.  But that doesn’t matter if you are using the data in your engine.  Then it’s whichever order your engine is using.  eEulerXYZ always means, “rotate around X, then Y, and then Z.”  How you combine the matrices to do that is dependent upon the majorness of the matrices.

#2: Fairly certain it uses FbxNode::RotationOrder.

L. Spiro