hw2 helper

by Rebecca Chen

HTML

<div id="info">Bounce & Contact
<br>left button to restart
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r70/three.min.js"></script>

CSS

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

body {
  overflow: hidden;
}

JavaScript

var camera, scene, renderer;
var pos, vel, force;
var m = 1;
var clock = new THREE.Clock();
var ballFrame;

init();
animate();

function init() {
    renderer = new THREE.WebGLRenderer({
      antialias: true
    });
	
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.setClearColor(0x888888);
  document.body.appendChild(renderer.domElement);

  scene = new THREE.Scene();
  camera = new THREE.OrthographicCamera(-50, 50, 50, -50, -10, 100);
  camera.position.z = 10;
  scene.add(camera);

  ////////////////////////////////////////////////////////////////////////////////////////////
	var floor = new THREE.Mesh (new THREE.PlaneGeometry(100,50), new THREE.MeshBasicMaterial({color:0xff1234}));
  floor.position.set (0,-25,0);
  scene.add (floor);
  
  var ball = new THREE.Mesh (new THREE.CircleGeometry(5,20), new THREE.MeshBasicMaterial({color:0x12ff34}));
  ballFrame = new THREE.Object3D();
  scene.add (ballFrame);
  ballFrame.add (ball);
  ball.position.y = 5;

	pos = new THREE.Vector3(-30,25,0);
	vel = new THREE.Vector3(5,0,0);
	force = new THREE.Vector3();
  
  window.addEventListener('resize', onWindowResize, false);
  window.addEventListener('mousedown', onDocumentMouseDown, false);
}

function onWindowResize() {
  camera.aspect = window.innerWidth / window.innerHeight;
  camera.updateProjectionMatrix();
  renderer.setSize(window.innerWidth, window.innerHeight);
}

function onDocumentMouseDown(event) {
  event.preventDefault();

  if (event.button === 0) { // left button to restart
		pos = new THREE.Vector3(-30,25,0);
  }
}

function animate() {
	var dt = clock.getDelta();

	force.set (0, -10, 0);
	vel.add (force.clone().multiplyScalar(1./m*dt));
	pos.add (vel.clone().multiplyScalar(dt));
  
  ballFrame.position.copy (pos);
	
 	// collision 
  if (pos.y < 0) {
  	pos.y = 0;
		vel.y *= -0.2;
  }
	
  // add contact force
  if (pos.y <= 0) {
      force.add (new THREE.Vector3(0,10,0));  // contact force
  }
  
	requestAnimationFrame(animate);
 ...