Game Engines

Introduction

A game engine is a piece of software which provides common game functionality for computer games. The purpose of a game engine is to allow the reuse of code from one game project to another, reducing time and cost of game development.

Some functionality provided by game engines are;

• 2D or 3D Graphics rendering
• Physics
• Collision Detection
• Audio
• Scripting animation Artificial Intelligence
• Networking
• Scene Graph
• Physics

Game engines vary in the amount of functionality provided in the areas mentioned above. Some game engine only provide graphics capability and should therefore be termed graphics engines.

Game engines were first popularized by the game "Doom" in the mid-1990's, developers licensed the core functionality of the game and created new games by changing the game assets, (levels, characters and weapons).

Games engines typically come in two forms;

• full source code, developers can modify, tweak and extend the engine to their exact specifications. With source code developers have maximum flexibility. This mode is normally very expensive however, as the game engine developer is giving access to all of its development work
• Compiled binaries with an API, game developers can only access the game engine as a compiled library, the available functionality is only that exposed through the API.

Middleware

Games engines are an example of "middleware", software provides high level solutions for games and other type of applications. Middleware normally provides an interface to a low-level API such as OpenGL or DirectX. Middle ware usually provides platform abstraction, allowing the same game to be run on different platforms

Integrated v's Loosely coupled

Middleware solutions can be integrated engines where all/most of the required functionality is brought together in a single package.

Alternatively a middle ware solution can be designed as a set of loosely connected components (Renderware)

Types Of Graphics Engine

Space Engines

• Simplest type
• objects tend not to intersect, so simple for HSR
• Most objects can be culled from view
• Intuitive Motion in 3D can be difficult

Terrain Engines

• Characters move or fly over a terrain
• Biped terain tracking can be difficult over rough terrain
• Managinging the terrain data can be a problem (use sectoring, LOD)

FPS indoor engines

• High detail and close quarters
• Complex Visibility algorithims needed
• Large detailed worlds needed
• Collision detection is difficult