Why does my Three.JS Environment Map Move?

Question

I have an a cubecamera at (0,0,0) as well as a giant sphere around it (textured on the inside).

The cubecamera creates a cubemap which is applied as the environment map for a second, smaller sphere.

When the second sphere moves on the screen its environment map reflection also moves.

My question is why does it move?

1. I am using an orthographic camera so I am always looking at the smaller sphere flat on, even if it moves left/right.

2. The cubecamera is the source of the environment map and the cubecamera does not move.

3. The giant sphere which the cubecamera builds its map from also does not move.

Answer 1

Environment mapping is a projection from the environment to your object, here the small sphere. So if the object changes position the mapping changes also. It does not matter it you are projecting using an orthographic camera or a perspective camera. It is still a positional based mapping.