Nullifying an angle in a Rotation Matrix

Question

Say I have a Rotation Matrix, which is used to rotate a 3D model. Is it possible to set the yaw of the rotation matrix to zero before applying it to the model?

Regards, Adam.

Answer 1

RotMatrix=R(yaw)*R(pitch)*R(roll)

to eliminate yaw factor, we can left-multiply this matrix on negative yaw matrix

RotMatrixNew=R(-yaw)*R(yaw)*R(pitch)*R(roll) = I**R*(pitch)*R(roll) = R(pitch)*R(roll)

If yaw angle isn't known before, then it could be calculated as

yaw = ArcTan2(RotMatrix[2][1], RotMatrix[1][1])