yojona/coyota.js

Behavior-based game engine

coyota.js

A very very simple game engine written in Javascript.

• Coyota.js uses the native ECMAScript Module syntax. You may want to run a local server.
• This project uses Collisions library

How to use it

Coyota.js provide two main functions, OnStart and Always. OnStart function will be executed the first time the game is run, Always is the game loop.

    OnStart(() => {
      screen.create(320, 240)    
    })

    Always(() => {
      // Write your game here
    })

Preload resources

It is highly recommended to preload your assets before using them. You can use the promise AssetManager.load () for that.

Use the Setup function to set up your game while your assets are loading. AssetManager is a global object.

let resources = {
  playerTexture: './assets/mauricio.png',
}

Setup(() => {
  screen.create(320, 240)    
})

AssetManager.load(resources).then(() => {

  let player

  OnStart(() => {
    player  = new Sprite(AssetManager.Textures.playerTexture, 160, 120, 24, 43, 12, 20)
  })

  Always(() => {
    player.draw()
  })
})

Create Sprite Animations

You need to import the Sprite and Animation classes from lib/Sprite/

OnStart(() => {
  player = new Sprite('./assets/mauricio.png', 160, 120, 24, 43, 12, 20)
        
  player.addAnimation({
    "Walk": new Animation(player.texture, 1, 3, 10) //source, initialFrame, lastFrame, speed)
  })
}

Always(() => {
  player.setAnimation("Walk").play()
  player.draw()
 })

Animated Sprite

Add behaviors

player.addBehavior(new Spinner(40))

Animated Sprite with Spinner Behavior

List of behaviors:

• Bullet
• Spinner
• Solid
• Platformer (work in progress)

Solid objects and collisions

This project uses Collisions library

All CoyotaObjects has a collider property. When an Sprite is created, collider initialize with a Polygon object from Collisions Library with the same size and position of the Sprite.

import Sprite from './lib/Sprite/Sprite.js' 
import Bullet from './behaviors/Bullet/Bullet.js'
import Solid from './behaviors/Solid/Solid.js'

let ball
let player
let cpu

  OnStart(() => {
    screen.create(320, 240)    

    ball    = new Sprite('./assets/ball.png', 160, 120, 8, 8, 4, 4)
    player  = new Sprite('./assets/paddle.png', 36, 120, 8, 40, 4, 20)
    cpu     = new Sprite('./assets/paddle.png', 280, 120, 8, 40, 4, 20)

    // new Bullet(speed, angleOfMotion, bounceOffSolids)
    ball.addBehavior(new Bullet(200, 0, true))
    cpu.addBehavior(new Solid())
    player.addBehavior(new Solid())

  })

  Always(() => {
    cpu.draw()
    ball.draw()
    player.draw()
  })

Simple pong

  ball.addBehavior(new Bullet(200, 0, true))
  cpu.addBehavior(new Solid())
  player.addBehavior(new Solid())