"use strict"; // 參考 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode
////////////////////////////////////////////////////////////////////////////////
// 銳利的鏡面反射
////////////////////////////////////////////////////////////////////////////////

var camera, scene, renderer;
var cameraControls;
var effectController;
var clock = new THREE.Clock();
var teapotSize = 600;
var tess = -1;	// 強制初始化
var ambientLight, light;
var teapot;
var phongBalancedMaterial;

var vertexShader = `
	varying vec3 vNormal;
	varying vec3 vViewPosition;

void main() {
		gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
		vNormal = normalize( normalMatrix * normal );
		vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );
		vViewPosition = -mvPosition.xyz;
	}
`

var fragmentShader = `
	uniform vec3 uMaterialColor;
	uniform vec3 uSpecularColor;

uniform vec3 uDirLightPos;
	uniform vec3 uDirLightColor;

uniform vec3 uAmbientLightColor;

uniform float uKd;
	uniform float uKs;
	uniform float shininess;

uniform float uDropoff;

varying vec3 vNormal;
	varying vec3 vViewPosition;

void main() {
		// 環境光
		gl_FragColor = vec4( uAmbientLightColor, 1.0 );

// 計算往光源的方向
		vec4 lDirection = viewMatrix * vec4( uDirLightPos, 0.0 );
		vec3 lVector = normalize( lDirection.xyz );

vec3 normal = normalize( vNormal );

// 漫射：N * L。法向量必須正規化，因為經過內插計算
		float diffuse = max( dot( normal, lVector ), 0.0);

// 這樣可能會切斷高光，但是比奇怪的閃爍好
		if (diffuse <= 0.0) {
			return;
		}

gl_FragColor.rgb += uKd * uMaterialColor * uDirLightColor * diffuse;

// 鏡面反射：N * H 的指數。H 是往光的向量加上往攝影機的向量正規化
		vec3 viewPosition = normalize( vViewPosition );
		vec3 pointHalfVector = normalize( lVector + viewPosition );
		float pointDotNormalHalf = max( dot( normal, pointHalfVector ), 0.0 );
		float specular = pow( pointDotNormalHalf, shininess );
		specular *= diffuse*(2.0 + shininess)/8.0;

// 學生作業：在這裡加入條件，當 specular < uDropoff　設為 0.0 否則設為 1.0

gl_FragColor.rgb += uDirLightColor * uSpecularColor * uKs * specular;
	}
`

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

// 光源
	ambientLight = new THREE.AmbientLight(0x333333); // 0.2

light = new THREE.DirectionalLight(0xffffff, 1.0);
	light.position.set(700, 3000, 1200);

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

// 攝影機
	camera = new THREE.PerspectiveCamera(45, canvasRatio, 1, 80000);
	camera.position.set(-1246, 35, -439);

// 控制
	cameraControls = new THREE.OrbitAndPanControls(camera, renderer.domElement);
	cameraControls.target.set(0, -436, 0);

// 材質
	// 筆記：將「逐像素」關閉不會影響鏡面高光
	// 只會影響「往光的方向」會不會逐像素計算
	var materialColor = new THREE.Color();
	materialColor.setRGB(1.0, 0.8, 0.6);

phongBalancedMaterial = createShaderMaterial("phongBalanced", light, ambientLight);
	phongBalancedMaterial.uniforms.uMaterialColor.value.copy(materialColor);
	phongBalancedMaterial.side = THREE.DoubleSide;
}

function createShaderMaterial(id, light, ambientLight) {
	var shaderTypes = {
		'phongBalanced' : {
			uniforms: {
				"uDirLightPos":	{ type: "v3", value: new THREE.Vector3() },
				"uDirLightColor": { type: "c", value: new THREE.Color( 0xffffff ) },
				"uAmbientLightColor": { type: "c", value: new THREE.Color( 0x050505 ) },
				"uMaterialColor":  { type: "c", value: new THREE.Color( 0xffffff ) },
				"uSpecularColor":  { type: "c", value: new THREE.Color( 0xffffff ) },
				uKd: {
					type: "f",
					value: 0.7
				},
				uKs: {
					type: "f",
					value: 0.3
				},
				shininess: {
					type: "f",
					value: 100.0
				},
				uDropoff: {
					type: "f",
					value: 0.5
				}
			}
		}
	};

var shader = shaderTypes[id];

var u = THREE.UniformsUtils.clone(shader.uniforms);

var vs = vertexShader;
	var fs = fragmentShader;

var material = new THREE.ShaderMaterial({ uniforms: u, vertexShader: vs, fragmentShader: fs });
	material.uniforms.uDirLightPos.value = light.position;
	material.uniforms.uDirLightColor.value = light.color;
	material.uniforms.uAmbientLightColor.value = ambientLight.color;

return material;

}

function setupGui() {
	effectController = {
		shininess: 100.0,
		dropoff: 0.5,
		ka: 0.2,
		kd: 0.4,
		ks: 0.35,
		metallic: false,

hue: 0.09,
		saturation: 0.46,
		lightness: 0.7,

lhue: 0.04,
		lsaturation: 0.0,
		llightness: 0.7,

// 奇怪的是如果你以負數初始化，這些滑桿不會顯示小數位
		lx: 0.65,
		ly: 0.43,
		lz: 0.35,
		newTess: 10
	};

var h;

var gui = new dat.GUI();

// 材質（屬性）
	h = gui.addFolder("材質控制");
	h.add(effectController, "shininess", 1.0, 1000.0, 1.0).name("閃亮程度");
	h.add(effectController, "dropoff", 0.0, 2.0, 0.025).name("衰減");
	h.add(effectController, "ka", 0.0, 1.0, 0.025).name("環境光係數");
	h.add(effectController, "kd", 0.0, 1.0, 0.025).name("漫射係數");
	h.add(effectController, "ks", 0.0, 1.0, 0.025).name("閃亮程度係數");
	h.add(effectController, "metallic").name("金屬色澤");
	h.add(effectController, "newTess", [2,3,4,5,6,8,10,12,16,24,32] ).name("鑲嵌等級");

// 材質（顏色）
	h = gui.addFolder("材質顏色");
	h.add(effectController, "hue", 0.0, 1.0, 0.025).name("色相");
	h.add(effectController, "saturation", 0.0, 1.0, 0.025).name("飽和度");
	h.add(effectController, "lightness", 0.0, 1.0, 0.025).name("明度");

// 光源（顏色）
	h = gui.addFolder("光源顏色");
	h.add(effectController, "lhue", 0.0, 1.0, 0.025).name("色相");
	h.add(effectController, "lsaturation", 0.0, 1.0, 0.025).name("飽和度");
	h.add(effectController, "llightness", 0.0, 1.0, 0.025).name("明度");

// 光源（方向）
	h = gui.addFolder("光源方向");
	h.add(effectController, "lx", -1.0, 1.0, 0.025).name("X");
	h.add(effectController, "ly", -1.0, 1.0, 0.025).name("Y");
	h.add(effectController, "lz", -1.0, 1.0, 0.025).name("Z");
}

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

function render() {
	var delta = clock.getDelta();

cameraControls.update(delta);

if (effectController.newTess !== tess ) {
		tess = effectController.newTess;

fillScene();
	}

phongBalancedMaterial.uniforms.shininess.value = effectController.shininess;
	phongBalancedMaterial.uniforms.uDropoff.value = effectController.dropoff;
	phongBalancedMaterial.uniforms.uKd.value = effectController.kd;
	phongBalancedMaterial.uniforms.uKs.value = effectController.ks;

var materialColor = new THREE.Color();
	materialColor.setHSL(effectController.hue, effectController.saturation, effectController.lightness);
	phongBalancedMaterial.uniforms.uMaterialColor.value.copy(materialColor);

if (!effectController.metallic) {
		materialColor.setRGB(1, 1, 1);
	}
	phongBalancedMaterial.uniforms.uSpecularColor.value.copy(materialColor);

// 環境光只是材質的顏色乘上 ka，無關光源的顏色
	ambientLight.color.setHSL(effectController.hue, effectController.saturation, effectController.lightness * effectController.ka);

light.position.set(effectController.lx, effectController.ly, effectController.lz);

light.color.setHSL(effectController.lhue, effectController.lsaturation, effectController.llightness);

renderer.render(scene, camera);
}

function fillScene() {
	scene = new THREE.Scene();
	scene.fog = new THREE.Fog(0x808080, 2000, 4000);

scene.add(camera);

scene.add(ambientLight);
	scene.add(light);

teapot = new THREE.Mesh(
		new THREE.TeapotGeometry(teapotSize, tess, true, true, true, true), phongBalancedMaterial);
	teapot.position.y = -teapotSize;

scene.add(teapot);
}

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