I'm trying to spin up my own 3D vector graphics engine, so I'd like to do this without an existing library. And I don't seem to be able to find the math for the correct approach in rotating an object around its own axis.
I can definitely do x/y/z rotations around a chosen point with values pt.x pt.y and pt.z. But I am unsure of how to make them unique to the object's orientation, so they are always being expressed in relation to the monitor (not even the environment yet, just the screen).
So which mathematical concept am I supposed to be applying here?