Andreas posted a BankAccount and ATM tutorial. This nicely demonstrates some of the basic Tweak concepts such as fields, events, triggers, and handlers, as well as introducing UI aspects like players, costumes, updating etc.
For high-quality prints you need high-quality screenshots. This means very high resolution, and nice anti-aliasing. Just grabbing the screen produces rather unpleasant results ( screenshot , 80 KB, 800x600 pixels). With normal OpenGL rendering you get rarely more than screen resolution, and anti-aliasing quality very much depends on your graphics board. So what to do? Tiled Rendering comes to the rescue. Instead of rendering the whole image at once, we render smaller portions of the scene, and then arrange the tiles into a large picture. However, just pointing the camera at each tile will not work as intended, the perspective would change from tile to tile. What is needed instead is to construct partial viewing frustums that together exactly recreate the whole frustum. This sounds like a lot of math, but actually it is quite simple: gluPerspective: fov aspect: aspect zNear: near zFar: far tile: rect | cotangent radians w h | radians := (fov/2.0) degreesToRadians. cotan