"use strict"; // 參考 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode
////////////////////////////////////////////////////////////////////////////////
// 粒子系統
////////////////////////////////////////////////////////////////////////////////
var camera, scene, renderer;
var cameraControls;

var clock = new THREE.Clock();

function fillScene() {
	scene = new THREE.Scene();

var geometry = new THREE.Geometry();

// 學生作業：改寫以下程式在每 100 單位產生一個頂點
	// 從 (-1000,-1000,-1000) 到 (1000,1000,1000)
	// 共 21*21*21 = 9261 點

for ( var i = 0; i < 8000; i ++ ) {

var vertex = new THREE.Vector3();
		// 只接受在圓內的點
		do {
			vertex.x = 2000 * Math.random() - 1000;
			vertex.y = 2000 * Math.random() - 1000;
			vertex.z = 2000 * Math.random() - 1000;
		} while ( vertex.length() > 1000 );

geometry.vertices.push( vertex );

}

var disk = THREE.ImageUtils.loadTexture( '/cs291/texture/disc.png' );
	var material = new THREE.ParticleBasicMaterial(
		{ size: 35, sizeAttenuation: false, map: disk, transparent: true } );
	material.color.setHSL( 0.9, 0.2, 0.6 );

var particles = new THREE.ParticleSystem( geometry, material );
	particles.sortParticles = true;
	scene.add( particles );
}

function init() {
	canvasWidth = window.innerWidth;
	canvasHeight = window.innerHeight;
	var canvasRatio = canvasWidth/canvasHeight;

// RENDERER
	renderer = new THREE.WebGLRenderer( { antialias: true } );
	renderer = new THREE.WebGLRenderer( { clearAlpha: 1 } );
	renderer.gammaInput = true;
	renderer.gammaOutput = true;
	renderer.setSize(canvasWidth, canvasHeight);
	renderer.setClearColorHex( 0xAAAAAA, 1.0 );

// 攝影機
	camera = new THREE.PerspectiveCamera( 55, canvasRatio, 2, 8000 );
	camera.position.set( 10, 5, 15 );

// 控制
	cameraControls = new THREE.OrbitAndPanControls(camera, renderer.domElement);
	cameraControls.target.set(0,0,0);

}

function addToDOM() {
	var container = document.getElementById('container');
	var canvas = container.getElementsByTagName('canvas');
	if (canvas.length>0) {
		container.removeChild(canvas[0]);
	}
	container.appendChild( renderer.domElement );
}

function animate() {
	window.requestAnimationFrame(animate);
	render();
}

function render() {
	var delta = clock.getDelta();
	cameraControls.update(delta);
	renderer.render(scene, camera);
}