ballanim-ball-update.js

update () {
  const { props, sceneProps } = this

  // bottom bound / floor
  if (this.y + props.radius >= sceneProps.height) {
    this.velY *= -props.bounce
    this.y = sceneProps.height - props.radius
    this.velX *= sceneProps.friction
  }
  // top bound / ceiling
  if (this.y - props.radius <= 0) {
    this.velY *= -props.bounce
    this.y = props.radius
    this.velX *= sceneProps.friction
  }

  // left bound
  if (this.x - props.radius <= 0) {
    this.velX *= -props.bounce
    this.x = props.radius
  }
  // right bound
  if (this.x + props.radius >= sceneProps.width) {
    this.velX *= -props.bounce
    this.x = sceneProps.width - props.radius
  }

  // reset insignificant amounts to 0
  if (this.velX < 0.01 && this.velX > -0.01) {
    this.velX = 0
  }
  if (this.velY < 0.01 && this.velY > -0.01) {
    this.velY = 0
  }

  // update position
  this.velY += sceneProps.gravity
  this.x += this.velX
  this.y += this.velY
}