Rotate around 3 axis

Unity Engine
1

I’m working on a function that merges two gameobjet’s meshes into a single one, in order to get the right position of the vertices I need to rotate all the vertices of the second meshes around all 3 axis, to do so I’m using the following code:

Move.RotateAround(Vector3.zero,Vector3.right ,angle.x);
Move.RotateAround(Vector3.zero,Vector3.up ,angle.y);
Move.RotateAround(Vector3.zero,Vector3.forward,angle.z);

But it only works correctly when **angle.z** is equal to zero, or when **angle.z** is different than zero and **angle.y** is zero, in all other cases I get imprecise results. The reason for this is that when I rotate around the X axis, the coordinates Y and Z change, so if I then rotate around the Z axis (which adjusts the X and Y coordinates), the value of Y has already changed so I’m actually applying some extra degrees to the rotation which leads to imprecision.

On the other hand, while I was experimenting with lighting I noticed that some times when I changed the rotation of the light’s transform in the inspector, if I changed the Z rotation it automatically affected the value of the X rotation and other times a change in the X rotation affected the Z rotation, I didn’t understand why at that moment, but now it seems obvious; Unity has and internal algorithm that kicks in when two rotations affect the same coordinate, can anyone explain how it works or the math involved?

2

You’re using the global axes for all three rotations. Try using Move.up and Move.forward instead of Vector3.up and Vector3.forward in the second and third lines.

3

Your observation does make scene, and pointed me in the right direction, but only Move.forward is needed, and you also need to reset the rotation for a second run, like this:

Move.rotation = Quaternion.identity;
Move.RotateAround(Vector3.zero,Vector3.right,angle.x);
Move.RotateAround(Vector3.zero,Vector3.up ,angle.y);
Move.RotateAround(Vector3.zero,Move.forward ,angle.z);

Thanks a lot!!!

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