So I am not sure is this possible. On the other hand it might be really simple but I cannot see it.
What I would like to achieve is this.
I want to have canvas element over the full screen height and width (so 100% both). OK got that
I want to be able to orbit around the mesh properly (so the target is in the center of the mesh) OK got that.
But I would like to be able to have mesh anywhere on the canvas (so anywhere on the screen, see image). But wherever it is I want rotations to behave the same way (so target is still in the center of the mesh, and I rotate around that mesh).