"use strict"; // 參考 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode
////////////////////////////////////////////////////////////////////////////////
// 頂點順序作業
// 你的作業是找出問題並修正頂點繪製順序
// 看看函式 someObject()
// 修正從 17 行開始的程式
////////////////////////////////////////////////////////////////////////////////

var camera, scene, renderer;
var windowScale;

function someObject(material) {
	var geometry = new THREE.Geometry();

// 給學生：有些資料必須被修正
	// 才會顯現兩個三角形！
	geometry.vertices.push( new THREE.Vector3( 3, 3, 0 ) );
	geometry.vertices.push( new THREE.Vector3( 7, 3, 0 ) );
	geometry.vertices.push( new THREE.Vector3( 7, 7, 0 ) );
	geometry.vertices.push( new THREE.Vector3( 3, 7, 0 ) );

geometry.faces.push( new THREE.Face3( 0, 1, 2 ) );
	geometry.faces.push( new THREE.Face3( 2, 0, 3 ) );

var mesh = new THREE.Mesh( geometry, material );

scene.add( mesh );
}

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 = 10;
	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( 5,4,0 );
	camera.position.x = focus.x;
	camera.position.y = focus.y;
	camera.position.z = 10;
	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 );
}

// 腳本本體
document.addEventListener("DOMContentLoaded", function () {
	try {
		init();
		showGrids();
		var material = new THREE.MeshBasicMaterial( { color: 0xF6831E, side: THREE.FrontSide } );
		someObject(material);
		addToDOM();
		render();
	} catch(e) {
		var errorReport = "Your program encountered an unrecoverable error, can not draw on canvas. Error was:<br/><br/>";
		$('#container').append(errorReport+e);
	}
})