Now, since each edge has two vanishing points, rotating the edge by 30° to the right, will "move the vanishing point by 30°", but the other vanishing point that we do not see will also move along with it. Eventually, when we reach 90°, the vanishing points will be on the sphere to the left and right, causing the edge to be parallel to the Picture Plane. Rotating it more than 90°, will cause the vanishing point that was behind the camera to now be in front, completing the cycle.

This also applies to objects constructed from multiple edges, such as a cube. If the cube is facing the camera, the horizontal lines go to the left and right VP, the vertical lines go to the up and down VP, and the forward lines go to the PP. This is "1 point perspective". Because only one VP is visible on the picture plane.

Rotating the cube around its Z axis will move the forward vanishing point AND the left vanishing point to the right, bringing it into view. This is "2 points perspective". Because now two VPs are visible on the picture plane.

Rotating the cube again around its X axis will move its visible VPs up (or down), together with the third VP from below (or above). This is "3 points perspective". Because now there are 3 VP visible on the picture plane.

Note: The 1, 2, 3 Point Perspective is not an inherent propert of the drawing, but a consequence of the objects' orientation within that drawing.