Something I do not understand. All the tutorials on OpenGL, DirectX, or other, always show you how to draw a shape and then change its vertices, move it around and so on. But all the games I know of, tutorials on creating, etc., always have sprites and sprites alone.
What is the reason for drawing triangles and squares for games? I never see it used, only pre-made graphics.
edit: based upon answers so far, is the purpose of drawing shapes to "bound" a sprite? So if I have a character, on a platformer like Mario, Mario has a shape around him and that shape's location is used to detect collisions, etc.?
edit: Maybe a small example?