cannon ball(class)

by 蔡 育曄

HTML

<div id="info">CannonBall
  <br/>按下空格鍵讓球跳動</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js"></script>
<script src="https://threejs.org/examples/js/controls/OrbitControls.js">
</script>
<script src="https://jyunming-chen.github.io/tutsplus/js/KeyboardState.js"></script>

CSS

#info {
  position: absolute;
  top: 0px;
  width: 100%;
  padding: 10px;
  text-align: center;
  color: #ffff00;
}

JavaScript

var camera, scene, renderer, controls;
var ball, stopped;
var keyboard = new KeyboardState();
var pos, vel, force;

init();
start();
animate();

function init() {

	scene = new THREE.Scene();

  camera = new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 1000);
  camera.position.z = 500;
  scene.add(camera);

  var gridXZ = new THREE.GridHelper(400, 20, 'red', 'white');
  scene.add(gridXZ);

  renderer = new THREE.WebGLRenderer();
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.setClearColor(0x888888);

  controls = new THREE.OrbitControls(camera, renderer.domElement);
  
  var geometry = new THREE.SphereGeometry(10, 20, 20);
  ball = new THREE.Mesh(geometry, new THREE.MeshNormalMaterial());
  scene.add(ball);
  
  pos = new THREE.Vector3();
  vel = new THREE.Vector3();
  force = new THREE.Vector3(0, -10, 0);
  
  document.body.appendChild(renderer.domElement);
  window.addEventListener('resize', onWindowResize, false);
  }
  
function onWindowResize() {
  var width = window.innerWidth;
  var height = window.innerHeight;
  camera.aspect = width / height;
  camera.updateProjectionMatrix();
  renderer.setSize(width, height);
}

function start() {
	stopped =false;
  vel.set(Math.random()-0.5,1,Math.random()-0.5).normalize().multiplyScalar(35);
}

function update(dt) {
	pos.add(vel.clone().multiplyScalar(dt));
  vel.add(force.clone().multiplyScalar(dt));
  if(pos.y<0){
  	pos.y = 0;
    stopped = true;
  }
}
function animate() {
  controls.update();
  ball.position.copy(pos);
  if(stopped){
  	keyboard.update();
    if(keyboard.down("space")) start();
  } else {
  update(0.1);
  }

	requestAnimationFrame(animate);
  render();
}

function render() {
  renderer.render(scene, camera);
}
window.focus();