62 lines
1.9 KiB
Markdown
62 lines
1.9 KiB
Markdown
*| [JavaECS](../README.md) | [docs](./overview.md) | implementation[]().md*
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# Implementation
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### Contents
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[Steps](#steps)
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[Example](#example)
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## Steps
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1. In the application's setup function, create an instance of `ECS`, with a specified maximum number of entity entries.
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2. Define the component classes, (or associate the primitive types) and register the components.
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3. Define the systems that interact with the components and register them
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4. Run the game.
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## Example
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``` java
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public static void main(){
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ECS gameEngine = new ECS(100);
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// Register the components, with a parameterised type
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gameEngine.registerComponent<coord>(coord.class.getName());
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gameEngine.registerComponent<ridgidBody>(ridgidbody.class.getName());
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// Register the system to run on the component
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gameEngine.registerSystem("ApplyGravitySystem", () -> {
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List<Integer> relevantEntities = gameEngine.getEntitiesWithComponent(ridgidBody.class.getName());
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for (Integer entity : relevantEntities) {
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coord c = (coord)gameEngine.getComponent(entity, coord.class.getName());
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ridgidBody r = (ridgidBody)gameEngine.getComponent(entity, ridgidBody.class.getName());
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c.y -= r.gravity;
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}
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});
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// Create an acutal game object
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int someEntity = gameEngine.createEntity();
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// Assign components to the new game object
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gameEngine.addComponent(someEntity, coord.class.getName(), new coord());
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gameEngine.addComponent(someEntity, ridgidBody.class.getName(), new ridgidBody());
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// Finally, enter into the game loop
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gameEngine.loop();
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}
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class coord{
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double x = 0.0;
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double y = 0.0;
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}
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class ridgidBody{
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double gravity = -9.81; // has a default value, unless overridden in the constructor
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ridgidBody(){}
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ridgidBody(double gravity){
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this.gravity = gravity;
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}
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}
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```
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### See also:
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[entity](./entity/entity.md)
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[component](./component/component.md)
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[system](./system/system.md)
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