I am working with .X file format export from blender.

In .X format export from blender,the keyframe information are stored in transformation matrix
format (it doesn’t have any option to export to seperate euler angle/translation keyframe).

The problem is,When my animation invole some rotation of root bone around an axis(Rigid body transformation ?),the linear interpolation give a very bad result(the model become flat/turn inside out)

I search on google and found this quaternion-thing.

question:

Since I dont have an euler angle to convert to quartenion,can I directly convert Transformation matrix into quartenion ?

will quatenion interpolation fix my rotation problem ?

You should check out geometric algebra, I recently started playing around with it and it makes many matrix and quaternion ideas much more intuitive. A good starting point is: