Rusher 2 – Introduction

Go to Rusher 2 project homepage

Here I’ll give a very brief introduction to Rusher 2, my next version of my component-based game engine for ActionScript 3.0.

Component-Based Game Engine

First off, what is a component-based game engine? In a component-based game engine, everything, literally everything, from physical information to AI behavior are represented as individual component. The most elemental unit in a component-based game engine is an entity, say the hero character, an enemy, or a collectable object in the game world. Each entity can have multiple components attached to it, fulfilling the entity’s logical purpose in the game. For instance, a hero character controlled by a player in the game can have: a physical data component, which contains the current position of the character; a view component, which holds a reference to a display object representing the appearance of the character in the game; and a controller component, which listens to player input from the player (keyboard, mouse, etc.) and then updates the physical data component by altering its underlying coordinate data.

Systems

Much like entities, the engine itself also contains multiple components with different responsibilities, which are known as systems. The most basic game engine generally consists of four systems: a clock system, which “ticks” every frame in order to keep the engine up and running (basically the clock invokes the main loop every frame); an input system, which listens for player input; an update system, which listens to the input system and update the game logic accordingly; and a rendering system, which draws the game onto the screen based on the current game state.

Dependency Injection

In generally, maintaining the intertwining references in a game engine is a daunting task. For instance, an engine needs to know what systems are added to it, an entity keeps track of its own components as well as needs to access components of other entities sometimes, and a command object needs to hold a reference to the game engine that its command manager belongs to. All this could result in tons of code dedicated to reference management. Making sure every single reference required is passed around correctly and removed as necessary is not easy. Hence, Rusher 2 makes use of SwiftSuspenders, a Dependency Injection framework mostly renowned for playing an important role in Robotlegs, one of the most popular MVC frameworks [...]

Read more: Rusher 2 – Introduction