Opengl rotate an object using the mouse (C++)

Question

I have an object that I want to rotate using the mouse in Opengl (I'm using glut). I'm keeping track of the mouse movement and rotate according to the change in x and y of the mouse. But the problem is that the object doesn't move how I want it to. For instance, when I move in x and then move in y and then move in x again, the object seems to move diagonally, while I want it to move from left to right. I know that this is because the newer rotations get done before the older rotations (resulting in unintuitive rotation) because of how matrix multiplication works.

But I have no idea of how to tackle this issue. One way I thought of is to change the axes about which I rotate according to the current rotation, but I have no idea if this will yield the correct result. Another thing I thought of is to make sure the latest rotation gets done last (but before glulookat translates the scene), but I don't know how to do this. So what would be the best way to solve this?

Answer 1

There are two main approaches you can take.

• Use quaternions by projecting mouse coordinates onto a sphere (the arcball approach). Make the sphere the size of the window, so you don't have to worry about clicking an object.

• Rotate about y for horizontal mouse movement. Then, for vertical mouse movement, rotate around the cross product of the view vector and y (be careful if the cross product is zero). This is the approach used by Maya and others for orienting an editing view.