Animate camera up

The camera position starts from the cube back, ends at the cube top. And the camera is always looking at the cube center. But camera up is (0, 1, 0) at the start position, and end width (0, 0, -1) at the end position, so how to animate the up, just the same as blender does?

I suggest you study how TrackballControls works. Unlike OrbitControls it does not maintain a fixed up vector but modifies it in order to transform the camera around the poles. You can check out its behavior in this demo:

Thanks! I will check out.