The drawing will resolve around 3 things:
1. The Horizon Line
2. The Left Vanishing Point
3. The Right Vanishing Point
The horizon line is where the eye sees the horizon. This is placed in the beginning of the drawing and can not be moved. In my example I have set it neer the center for simplicity, but you can move it to any place on the plane to create different points of view. In two point perspective the vanishing points are chosen for you. They are the left and right extremes of the Horizon line. All of our guidelines will be drawn 2 either of these two points.
In 1 point perspective you only see one side of the structures. In 2 point perspective, both the left and right side of the structure are seen. This technique is great for drawing things with a view at the corner of the structure, such as a building or a city corner, but the technique can be used for mapping out softer subjects as well.
You will only see the bottom of the structure if the bottom of it is above the horizon line. conversely You will only see the top of the structure if it is bellow the Horizon line.
We start by drawing the vertical line that is the corner of the cube. Your fist guidelines are for the sides the lines to the left go to the left vanishing point, and the lines to the right go to the right vanishing point. Drawing the bottom (or top) of the structure gets more complicated. Here we draw our guidelines to the opposite Vanishing point. You see in the example, that once the boundaries of the bottom are defined, the guidelines are drawn to the opposite vanishing points.
Once the guidelines are set, you then add vertical lines for the side corners. and erase your guidelines. Bellow we see the finished cube as well as a cube set bellow the horizon line.
These tools can be used to add many details like windows and inlets, to create architectural drawings. They can also be loosely used for a whimsical painter effect. The Basic understanding of perspective is a necessary tool in all artist's and designer's tool chest.