59 lines
1.9 KiB
Markdown
59 lines
1.9 KiB
Markdown
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---
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title: "World Builder"
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date: 2019-05-22T13:40:25-07:00
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weight: 35
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---
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WorldBuilder is used to construct a World from Engines, Renderers, and an initial state of Entities, Components, and Messages.
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The WorldBuilder enforces certain rules about Engine structure. It is forbidden to have messages create cycles between Engines, and no Component may be mutated by more than one Engine.
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The WorldBuilder uses Engines and their Message read/emit information to determine a valid ordering of the Engines, which is given to the World.
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Here is an example usage:
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```ts
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class Game {
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private World world;
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...
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public load() {
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import { WorldBuilder } from "encompass-ecs";
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import { CanvasComponent } from "./components/canvas";
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import { PositionComponent } from "./components/position";
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import { VelocityComponent } from "./components/velocity";
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import { MotionEngine } from "./engines/motion";
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import { CanvasRenderer } from "./renderers/canvas";
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const world_builder = new WorldBuilder();
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world_builder.add_engine(MotionEngine);
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world_builder.add_renderer(CanvasRenderer);
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const entity = world_builder.create_entity();
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const position_component = entity.add_component(PositionComponent);
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position_component.x = 0;
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position_component.y = 0;
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const velocity_component = entity.add_component(VelocityComponent);
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velocity_component.x = 20;
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velocity_component.y = 0;
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const sprite_component = entity.add_component(SpriteComponent);
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canvas_component.canvas = love.graphics.newImage("assets/sprites/ball.png");
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this.world = world_builder.build();
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}
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...
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}
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```
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Now our game will initialize with a ball that moves horizontally across the screen!
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{{% notice tip %}}
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Make sure that you remember to add Engines to the WorldBuilder when you define them. Otherwise nothing will happen, which can be very embarrassing.
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{{% /notice %}}
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