We can get Euler angles from rotation matrix using following formula. Given a 3×3 rotation matrix The 3 Euler angles are Here atan2 is the same arc tangent function, with quadrant checking, you typically find in C or Matlab. Note: Care must be taken if the angle around the y-axis is exactly +/-90°. In that … Read more
One possible solution I found: (r2 * Quaternion.Inverse(r1)).eulerAngles.Y
First read: Understanding 4×4 homogenous transform matrices as I use terminology from there. Well I was too lazy to equate the whole stuff for my environment but based on this: Computing Euler angles from a rotation matrix The resulting 3D rotation sub matrix of m for any rotation order will always have these therms: (+/-)sin(a) … Read more