"use strict"; // 參考 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode
////////////////////////////////////////////////////////////////////////////////
// 畫一個方形的練習
// 你的作業是完成一個畫方形的函式（在 28 行）
// 函式接收 4 個參數 － 座標 x1, y1, x2, y2
// 作為方形頂點，回傳一個幾何物件 (THREE.Geometry())
// 滿足 x1, y1, x2, y2 定義的方形
////////////////////////////////////////////////////////////////////////////////

var camera, scene, renderer;
var windowScale;

function exampleTriangle() {
	// 以下程式碼展示如何畫一個三角形
	var triangle = new THREE.Geometry();
	triangle.vertices.push( new THREE.Vector3( 1, 1, 0 ) );
	triangle.vertices.push( new THREE.Vector3( 3, 1, 0 ) );
	triangle.vertices.push( new THREE.Vector3( 3, 3, 0 ) );

triangle.faces.push( new THREE.Face3( 0, 1, 2 ) );

return triangle;
}

function drawSquare(x1, y1, x2, y2) {

var square = new THREE.Geometry();
	// 你的程式要寫在這裡

// 不要忘記回傳幾何物件，下一行是必要的
	return square;
}

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

// 場景
	scene = new THREE.Scene();

// 攝影機：Y 上，X 右，Z 前
	windowScale = 12;
	var windowWidth = windowScale * canvasRatio;
	var windowHeight = windowScale;

camera = new THREE.OrthographicCamera(windowWidth/-2, windowWidth/2, windowHeight/2, windowHeight/-2, 0, 40);

var focus = new THREE.Vector3( 5,5,0 );
	camera.position.x = focus.x;
	camera.position.y = focus.y;
	camera.position.z = 20;
	camera.lookAt(focus);

renderer = new THREE.WebGLRenderer({ antialias: true, preserveDrawingBuffer: true});
	renderer.gammaInput = true;
	renderer.gammaOutput = true;
	renderer.setSize( canvasWidth, canvasHeight );
	renderer.setClearColorHex( 0xFFFFFF, 1.0 );
}

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 render() {
	renderer.render( scene, camera );
}