Drawing a Cube in One-Point Perspective
Step 1. Lightly sketch the general shape of the face of the cube.
Step 2. Lightly draw the two angle lines along the top until they cross.
Step 3. At the point where they cross, draw a horizontal line parallel to the top and bottom lines of the cube. This is the horizon line.
Now, place a vanishing point where the lines cross. (This is the way to find the horizon line and vanishing point using the angles from an object - a cube, a table, etc.) Step 4. Draw a parallel line between the horizon line and the top of the cube. This establishes the top surface of the cube. Darken the lines. Here is a cube drawn in perfect one-point perspective.
Originally posted by johnnyforeverBump
http://www.killermovies.com/forums/376326_13404-1-000-000th-post-game