data oriented, functional entity component system.
This is a minimal example of what you can do with ecs
. It's not functional but
illustrates how to declare your components, systems, and entities.
import ECS from 'ecs'
import Keyboard from './my/game/keyboard.js'
import clamp from 'clamp'
// generates a new entity component system
const world = ECS.createWorld()
// define a component type named position and give it a default value
const POSITION = ECS.createComponentType(world, 'position', { x: 0, y: 0 })
// define another component type named moveable
const MOVEABLE = ECS.createComponentType(world, 'moveable', { dx: 0, dy: 0 })
// set up the player
const PLAYER = ECS.createEntity(world)
ECS.addComponentToEntity(world, PLAYER, POSITION)
ECS.addComponentToEntity(world, PLAYER, MOVEABLE)
// update entity velocity based on key pressed
function keyboardControlSystem (world) {
// declare a filter that is used at run time to choose which entities to operate on
// the 2nd argument is all of the required component types the entity must have to
// be included
const moveableFilter = ECS.createFilter(world, [ MOVEABLE ])
// called each game loop
const onUpdate = function () {
// get all of the entities in the world that pass the filter
for (const entity of ECS.getEntities(world, moveableFilter)) {
// update the entity position according to what is pressed
if (Keyboard.keyPressed('up'))
entity.moveable.dy -= 1;
if (Keyboard.keyPressed('down'))
entity.moveable.dy += 1;
if (Keyboard.keyPressed('left'))
entity.moveable.dx -= 1;
if (Keyboard.keyPressed('right'))
entity.moveable.dx += 1;
entity.moveable.dx = clamp(entity.moveable.dx, -10, 10);
entity.moveable.dy = clamp(entity.moveable.dy, -10, 10);
}
}
return { onUpdate }
}
function movementSystem (world) {
const positionMoveFilter = ECS.createFilter(world, [ POSITION, MOVEABLE ])
const onUpdate = function () {
for (const entity of ECS.getEntities(world, positionMoveFilter)) {
entity.position.x += entity.moveable.dx
entity.position.y += entity.moveable.dy
}
}
return { onUpdate }
}
ECS.addSystem(world, keyboardControlSystem)
ECS.addSystem(world, movementSystem)
function gameLoop() {
// run onUpdate for all added systems
ECS.update(world);
requestAnimationFrame(gameLoop);
}
// finally start the game loop
gameLoop()