Zack Booth Simpson

Game Programming Patterns OR Design Pattern for Computer Games

Simpson thinks "an industry-wide shared vocabulary would be a very good thing". As such, he has taken the work of Gamma et. al., to do with Object-Oriented Software Design Patterns, and applied the idea to game programming. Inspired by Smalltalk's Model-View-Controller pattern (which corresponds to Gamma et. al's Observer pattern and combinations with Composite, Factory Method and Strategy patterns), Simspson has created 3 categories of patterns (or classes):

• Model
• Model Database
• Spatial Index
• Gateway
• Type Database
• View
• Render Delegation
• Appearance Map
• Controller
• Mini-kernel
• Double Buffered State
• Trigger
• Controller State Machine
• Usecode

This list is very much programming-specific. It is not meant to be complete or apply to all types of games, but instead has a bias in favour of fixed-point-of-view real-time-strategy/adventure games due to the author's experience with them.

The three fundamental patterns, Model, View and Controller have the following properties:

• Model
• maintains state of game world
• read-only by Views
• read-write by Controllers
• View
• knows how to render Models
• invisible to Models
• invisible to Controllers
• Controller
• process, changes state of Models
  
• created by Models
  
• (yet) invisible to Models
• invisible to Views

The format of this catalogue also borrows from the original, with sections:

• Also Known As -- other names for the pattern
  
• Intent -- what the pattern does
  
• Motivation -- why the pattern is needed
  
• Implementation -- issues to do with coding
  
• Related Patterns -- similar patterns and suggested combinations
  
• Thanks to -- acknowledging expert advice
  

Some of the patterns defined by Simpson are possibly unrecognised combinations (or redefinitions) of patterns by Gamma et. al., however the listing for each new pattern at least references existing patterns it is related to. The collection of game programming patterns is, as the title suggests, specific to programming and is not necessarily applicable to design at the level of gameplay. Nonetheless they give valuable insight into the structure of a game from a game-as-code perspective.