slingshot.js

// Angry Birds with Matter.js
// The Coding Train / Daniel Shiffman
// https://thecodingtrain.com/challenges/content/videos/challenges/138-angry-birds-with-matterjs
// https://youtu.be/TDQzoe9nslY

// Code from Challenge: https://editor.p5js.org/codingtrain/sketches/UOR4nIcNS

class SlingShot {
  constructor(x, y, rock) {
    const options = {
      pointA: {
        x: x,
        y: y
      },
      bodyB: rock,
      stiffness: 0.02,
      length: 40
    };
    this.sling = Constraint.create(options);
    World.add(world, this.sling);
  }

  fly() {
    this.sling.bodyB = null;
  }

  show() {
    if (this.sling.bodyB) {
      stroke(0);
      strokeWeight(4);
      const posA = this.sling.pointA;
      const posB = this.sling.bodyB.position;
      line(posA.x, posA.y, posB.x, posB.y);
    }
  }

  attach(body) {
    this.sling.bodyB = rock;
  }
}