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A Simple Game with Multiple UIs

Yahtzee itself is a very simple dice game, and needs no introduction. I wrote this program as a way to experiment with different ways to implement multiple user interfaces on top of game logic.

This program comes with three separate interfaces:

Which interface to use is partly determined at runtime, depending on the current environment. You can also choose to leave out the SDL interface and/or the curses-based interface at compile-time. (The dumb text interface is always included, since it is very small and incurs no external dependencies.)

The three interfaces have different behaviors, and each one is suited to the particulars of its capabilities. The graphical user interface, for example, reacts appropriately to mouse-over events, as well as mouse clicks and dragging. The curses interface is a little more coarse-grained, in that every input event (i.e. keystroke) corresponds to a user action. The plain-text interface is even more coarse-grained, since a single input event can correspond to multiple user actions (from the point of view of the game logic). Other issues such as displaying help at run-time are also handled in a distinct way for each interface.

My other goal in writing this program was to experiment with creating the elements of a comfortable graphical interface. SDL does not provide its users with access to any of a given platform's native GUI elements (such as menus or pushbuttons), and indeed using such things typically requires that a program be designed to accommodate the platform's specific event-driven model — all of which interferes with the goal of keeping the user interface in its own separate black box.

The game logic code is aware of the various interface elements, since its whole purpose is to update the game state in reaction to the various user actions. But the user interface code is free to provide other "actions" that don't alter the game state but are needed to make a good user experience — such as rendering the pushbutton as depressed when the mouse button is down and not yet released, or having the score sheet elements display helpful information on mouse-over.

Some people may also find interesting the code that creates the images of the die faces at runtime, using some basic floating-point math.

The code in this distribution is made available under the MIT license. Share and Enjoy. Questions and comments should be directed to me at

Brian Raiter