Linear Perspective of the Cube

Horizon line, directly opposite the viewer's eye, represents objects infinitely far away. They have shrunk, in the distance, to the infinitesimal thickness of a line. It is analogous to (and named after) the Earth's horizon. Any perspective representation of a scene that includes parallel lines has one or more vanishing points in a perspective drawing. A one-point perspective drawing means that the drawing has a single vanishing point, usually (though not necessarily) directly opposite the viewer's eye and usually on the horizon line. All lines parallel with the viewer's line of sight recede to the horizon towards this vanishing point. A two-point drawing would have lines parallel to two different angles.
Drag the top view D1 of the corner D to change the position of the cube.