In Processing, drawing shapes is key to the program. Otherwise, nothing would appear on the screen. This section will tell you how basic shapes are drawn.
|x1||x-coordinate of the first point|
|y1||y-coordinate of the first point|
|z1||z-coordinate of the first point|
|x2||x-coordinate of the second point|
|y2||y-coordinate of the second point|
|z2||z-coordinate of the second point|
|x3||x-coordinate of the third point|
|y3||y-coordinate of the third point|
You can find a reference on Processing's foundation.