# 渲染到纹理

```html
<div class="page-header"><h3>16、渲染到纹理</h3></div>

<canvas id = "test16-canvas" width = "800" height = "600"></canvas>
<br/>
笔记本模型来自:
<a href="http://www.turbosquid.com/3d-models/apple-macbook-max-free/391534">
this 3DS Max model by Xedium
</a>
<br/>
月球表面纹理图片来自:
<a href="http://maps.jpl.nasa.gov/">the Jet Propulsion Laboratory</a>.
<br/>

<script id = "per-fragment-lighting-vs" type = "x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec3 aVertexNormal;
attribute vec2 aTextureCoord;

uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform mat3 uNMatrix;

varying vec2 vTextureCoord;
varying vec3 vTransformedNormal;
varying vec4 vPosition;


void main(void)
{
vPosition = uMVMatrix * vec4(aVertexPosition, 1.0);
gl_Position = uPMatrix * vPosition;
vTextureCoord = aTextureCoord;
vTransformedNormal = uNMatrix * aVertexNormal;
}
</script>
<script id = "per-fragment-lighting-fs" type = "x-shader/x-fragment">
precision mediump float;

varying vec2 vTextureCoord;
varying vec3 vTransformedNormal;
varying vec4 vPosition;

uniform vec3 uMaterialAmbientColor;
uniform vec3 uMaterialDiffuseColor;
uniform vec3 uMaterialSpecularColor;
uniform float uMaterialShininess;
uniform vec3 uMaterialEmissiveColor;

uniform bool uShowSpecularHighlights;
uniform bool uUseTextures;

uniform vec3 uAmbientLightingColor;

uniform vec3 uPointLightingLocation;
uniform vec3 uPointLightingDiffuseColor;
uniform vec3 uPointLightingSpecularColor;

uniform sampler2D uSampler;


void main(void)
{
vec3 ambientLightWeighting = uAmbientLightingColor;

vec3 lightDirection = normalize(uPointLightingLocation - vPosition.xyz);
vec3 normal = normalize(vTransformedNormal);

vec3 specularLightWeighting = vec3(0.0, 0.0, 0.0);
if (uShowSpecularHighlights)
{
vec3 eyeDirection = normalize(-vPosition.xyz);
vec3 reflectionDirection = reflect(-lightDirection, normal);

float specularLightBrightness =
pow(max(dot(reflectionDirection, eyeDirection), 0.0),
uMaterialShininess);
specularLightWeighting =
uPointLightingSpecularColor * specularLightBrightness;
}

float diffuseLightBrightness = max(dot(normal, lightDirection), 0.0);
vec3 diffuseLightWeighting =
uPointLightingDiffuseColor * diffuseLightBrightness;

vec3 materialAmbientColor = uMaterialAmbientColor;
vec3 materialDiffuseColor = uMaterialDiffuseColor;
vec3 materialSpecularColor = uMaterialSpecularColor;
vec3 materialEmissiveColor = uMaterialEmissiveColor;
float alpha = 1.0;
if (uUseTextures)
{
vec4 textureColor =
texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
materialAmbientColor = materialAmbientColor * textureColor.rgb;
materialDiffuseColor = materialDiffuseColor * textureColor.rgb;
materialEmissiveColor = materialEmissiveColor * textureColor.rgb;
alpha = textureColor.a;
}
gl_FragColor = vec4(
materialAmbientColor * ambientLightWeighting +
materialDiffuseColor * diffuseLightWeighting +
materialSpecularColor * specularLightWeighting +
materialEmissiveColor,
alpha
);
}
</script>
<script type="text/javascript">
requestAnimFrame = window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.msRequestAnimationFrame ||
window.oRequestAnimationFrame ||
function(callback) { setTimeout(callback, 1000 / 60); };
</script>
<script type="text/javascript">
$(document).ready(function ()
{
webGLStart();
});

function webGLStart()
{
var canvas = $("#test16-canvas");
initGL(canvas[0]);
initTextureFramebuffer();
initShaders();
initTextures();
initBuffers();

loadLaptop();

gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);

waitTexture = setInterval("tick()", 100);
}

var textureFlag = [0, 0, 0];
var startTick = false;
var waitTick;
function tick()
{
if(textureFlag[0] == 1 && textureFlag[1] == 1 && textureFlag[2] == 1)
{
startTick = true;
textureFlag[0] = 2;
textureFlag[1] = 2;
textureFlag[2] = 2;
clearInterval(waitTexture);
}
if(startTick)
{
requestAnimFrame(tick);
drawScene();
animate();
}
}
var gl;
function initGL(canvas)
{
try
{
gl = canvas.getContext("webgl") || canvas.getContext("experimental-webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
}catch(e){}
if(!gl)
{
alert("无法初始化“WebGL”。");
}
}
var rttFramebuffer;
var rttTexture;
function initTextureFramebuffer()
{
rttFramebuffer = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, rttFramebuffer);
rttFramebuffer.width = 512;
rttFramebuffer.height = 512;

rttTexture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, rttTexture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
// gl.generateMipmap(gl.TEXTURE_2D);

gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA,
rttFramebuffer.width, rttFramebuffer.height,
0, gl.RGBA, gl.UNSIGNED_BYTE, null);

var renderbuffer = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, renderbuffer);
gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16,
rttFramebuffer.width, rttFramebuffer.height);

gl.framebufferTexture2D(
gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, rttTexture, 0);
gl.framebufferRenderbuffer(
gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, renderbuffer);

gl.bindTexture(gl.TEXTURE_2D, null);
gl.bindRenderbuffer(gl.RENDERBUFFER, null);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
}
var moonTexture;
var crateTexture;
function initTextures()
{
moonTexture = gl.createTexture();
moonTexture.image = new Image();
moonTexture.image.onload = function ()
{
handleLoadedTexture(moonTexture)
textureFlag[0] = 1;
}
moonTexture.image.src = "/Public/image/moon.gif";

crateTexture = gl.createTexture();
crateTexture.image = new Image();
crateTexture.image.onload = function ()
{
handleLoadedTexture(crateTexture)
textureFlag[1] = 1;
}
crateTexture.image.src = "/Public/image/crate.gif";
}
function handleLoadedTexture(texture)
{
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, 1);


gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA,
gl.UNSIGNED_BYTE, texture.image);
gl.texParameteri(gl.TEXTURE_2D,
gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D,
gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);

gl.generateMipmap(gl.TEXTURE_2D);

gl.bindTexture(gl.TEXTURE_2D, null);
}
function getShader(gl, id)
{
var shaderScript = $("#" + id);
if(!shaderScript.length)
{
return null;
}
var str = shaderScript.text();

var shader;
if(shaderScript[0].type == "x-shader/x-fragment")
{
shader = gl.createShader(gl.FRAGMENT_SHADER);
}
else if(shaderScript[0].type == "x-shader/x-vertex")
{
shader = gl.createShader(gl.VERTEX_SHADER);
}
else
{
return null;
}
gl.shaderSource(shader, str);
gl.compileShader(shader);
if(!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
{
alert(gl.getShaderInfoLog(shader));
return null;
}
return shader;
}

var shaderProgram;

function initShaders()
{
var vertexShader = getShader(gl, "per-fragment-lighting-vs");
var fragmentShader = getShader(gl, "per-fragment-lighting-fs");

shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram (shaderProgram );
if(!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS))
{
alert("无法初始化“Shader”。");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute =
gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);

shaderProgram.vertexNormalAttribute =
gl.getAttribLocation(shaderProgram, "aVertexNormal");
gl.enableVertexAttribArray(shaderProgram.vertexNormalAttribute);

shaderProgram.textureCoordAttribute =
gl.getAttribLocation(shaderProgram, "aTextureCoord");
gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);

shaderProgram.pMatrixUniform =
gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform =
gl.getUniformLocation(shaderProgram, "uMVMatrix");
shaderProgram.nMatrixUniform =
gl.getUniformLocation(shaderProgram, "uNMatrix");
shaderProgram.samplerUniform =
gl.getUniformLocation(shaderProgram, "uSampler");

shaderProgram.materialAmbientColorUniform =
gl.getUniformLocation(shaderProgram, "uMaterialAmbientColor");
shaderProgram.materialDiffuseColorUniform =
gl.getUniformLocation(shaderProgram, "uMaterialDiffuseColor");
shaderProgram.materialSpecularColorUniform =
gl.getUniformLocation(shaderProgram, "uMaterialSpecularColor");
shaderProgram.materialShininessUniform =
gl.getUniformLocation(shaderProgram, "uMaterialShininess");
shaderProgram.materialEmissiveColorUniform =
gl.getUniformLocation(shaderProgram, "uMaterialEmissiveColor");
shaderProgram.showSpecularHighlightsUniform =
gl.getUniformLocation(shaderProgram, "uShowSpecularHighlights");
shaderProgram.useTexturesUniform =
gl.getUniformLocation(shaderProgram, "uUseTextures");
shaderProgram.ambientLightingColorUniform =
gl.getUniformLocation(shaderProgram, "uAmbientLightingColor");
shaderProgram.pointLightingLocationUniform =
gl.getUniformLocation(shaderProgram, "uPointLightingLocation");
shaderProgram.pointLightingSpecularColorUniform =
gl.getUniformLocation(shaderProgram, "uPointLightingSpecularColor");
shaderProgram.pointLightingDiffuseColorUniform =
gl.getUniformLocation(shaderProgram, "uPointLightingDiffuseColor");
}

var mvMatrix = mat4.create();

var mvMatrixStack = [];

var pMatrix = mat4.create();

function mvPushMatrix()
{
var copy = mat4.clone(mvMatrix);
mvMatrixStack.push(copy);
}
function mvPopMatrix()
{
if(mvMatrixStack.length == 0)
{
throw "不合法的矩阵出栈操作!";
}
mvMatrix = mvMatrixStack.pop();
}

function setMatrixUniforms()
{
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);

var normalMatrix = mat3.create();

mat3.fromMat4(normalMatrix, mvMatrix);
mat3.invert(normalMatrix, normalMatrix);
mat3.transpose(normalMatrix, normalMatrix);

gl.uniformMatrix3fv(shaderProgram.nMatrixUniform, false, normalMatrix);
}

var laptopVertexPositionBuffer;
var laptopVertexNormalBuffer;
var laptopVertexTextureCoordBuffer;
var laptopVertexIndexBuffer;
function loadLaptop()
{
$.getJSON(
"/Public/json/macbook.json",
function(data)
{
handleLoadedLaptop(data);
textureFlag[2] = 1;
}
);
}
function handleLoadedLaptop(laptopData)
{
laptopVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, laptopVertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(laptopData.vertexNormals), gl.STATIC_DRAW);
laptopVertexNormalBuffer.itemSize = 3;
laptopVertexNormalBuffer.numItems = laptopData.vertexNormals.length / 3;

laptopVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, laptopVertexTextureCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(laptopData.vertexTextureCoords), gl.STATIC_DRAW);
laptopVertexTextureCoordBuffer.itemSize = 2;
laptopVertexTextureCoordBuffer.numItems =
laptopData.vertexTextureCoords.length / 2;

laptopVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, laptopVertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(laptopData.vertexPositions), gl.STATIC_DRAW);
laptopVertexPositionBuffer.itemSize = 3;
laptopVertexPositionBuffer.numItems = laptopData.vertexPositions.length / 3;

laptopVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, laptopVertexIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array(laptopData.indices), gl.STREAM_DRAW);
laptopVertexIndexBuffer.itemSize = 1;
laptopVertexIndexBuffer.numItems = laptopData.indices.length;
}

var cubeVertexPositionBuffer;
var cubeVertexNormalBuffer;
var cubeVertexTextureCoordBuffer;
var cubeVertexIndexBuffer;

var moonVertexPositionBuffer;
var moonVertexNormalBuffer;
var moonVertexTextureCoordBuffer;
var moonVertexIndexBuffer;

var laptopScreenVertexPositionBuffer;
var laptopScreenVertexNormalBuffer;
var laptopScreenVertexTextureCoordBuffer;

function initBuffers()
{
//箱子
cubeVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
vertices = [
// 正面
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, 1.0,

// 背面
-1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, 1.0, -1.0,
1.0, -1.0, -1.0,

// 顶部
-1.0, 1.0, -1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
1.0, 1.0, -1.0,

// 底部
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
1.0, -1.0, 1.0,
-1.0, -1.0, 1.0,

// 右侧面
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
1.0, 1.0, 1.0,
1.0, -1.0, 1.0,

// 左侧面
-1.0, -1.0, -1.0,
-1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
-1.0, 1.0, -1.0,
];
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(vertices), gl.STATIC_DRAW);
cubeVertexPositionBuffer.itemSize = 3;
cubeVertexPositionBuffer.numItems = 24;

cubeVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexNormalBuffer);
var vertexNormals = [
// 正面
0.0, 0.0, 1.0,
0.0, 0.0, 1.0,
0.0, 0.0, 1.0,
0.0, 0.0, 1.0,

// 背面
0.0, 0.0, -1.0,
0.0, 0.0, -1.0,
0.0, 0.0, -1.0,
0.0, 0.0, -1.0,

// 顶部
0.0, 1.0, 0.0,
0.0, 1.0, 0.0,
0.0, 1.0, 0.0,
0.0, 1.0, 0.0,

// 底部
0.0, -1.0, 0.0,
0.0, -1.0, 0.0,
0.0, -1.0, 0.0,
0.0, -1.0, 0.0,

// 右侧面
1.0, 0.0, 0.0,
1.0, 0.0, 0.0,
1.0, 0.0, 0.0,
1.0, 0.0, 0.0,

// 左侧面
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
];
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(vertexNormals), gl.STATIC_DRAW);
cubeVertexNormalBuffer.itemSize = 3;
cubeVertexNormalBuffer.numItems = 24;

cubeVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
textureCoords = [
// 正面
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,

// 背面
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,

// 顶部
0.0, 1.0,
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,

// 底部
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
1.0, 0.0,

// 右侧面
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,

// 左侧面
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
];
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(textureCoords), gl.STATIC_DRAW);
cubeVertexTextureCoordBuffer.itemSize = 2;
cubeVertexTextureCoordBuffer.numItems = 24;

cubeVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
var cubeVertexIndices =
[
0, 1, 2, 0, 2, 3, // 正面
4, 5, 6, 4, 6, 7, // 背面
8, 9, 10, 8, 10, 11, // 顶部
12, 13, 14, 12, 14, 15, // 底部
16, 17, 18, 16, 18, 19, // 右侧面
20, 21, 22, 20, 22, 23 // 左侧面
];
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
cubeVertexIndexBuffer.itemSize = 1;
cubeVertexIndexBuffer.numItems = 36;

//月亮
var latitudeBands = 30;
var longitudeBands = 30;
var radius = 1;
var vertexPositionData = [];
var normalData = [];
var textureCoordData = [];
for(var latNumber = 0; latNumber <= latitudeBands; latNumber ++)
{
var theta = latNumber * Math.PI / latitudeBands;
var sinTheta = Math.sin(theta);
var cosTheta = Math.cos(theta);
for(var longNumber = 0; longNumber <= longitudeBands; longNumber ++)
{
var phi = longNumber * 2 * Math.PI / longitudeBands;
var sinPhi = Math.sin(phi);
var cosPhi = Math.cos(phi);
var x = cosPhi * sinTheta;
var y = cosTheta;
var z = sinPhi * sinTheta;
var u = 1 - (longNumber / longitudeBands);
var v = 1 - (latNumber / latitudeBands);

normalData.push(x);
normalData.push(y);
normalData.push(z);
textureCoordData.push(u);
textureCoordData.push(v);
vertexPositionData.push(radius * x);
vertexPositionData.push(radius * y);
vertexPositionData.push(radius * z);
}
}
var indexData = [];
for(var latNumber = 0; latNumber < latitudeBands; latNumber ++)
{
for(var longNumber = 0; longNumber < longitudeBands; longNumber ++)
{
var first = (latNumber * (longitudeBands + 1)) + longNumber;
var second = first + longitudeBands + 1;
indexData.push(first);
indexData.push(second);
indexData.push(first + 1);
indexData.push(second);
indexData.push(second + 1);
indexData.push(first + 1);
}
}
moonVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(normalData), gl.STATIC_DRAW);
moonVertexNormalBuffer.itemSize = 3;
moonVertexNormalBuffer.numItems = normalData.length / 3;

moonVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexTextureCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(textureCoordData), gl.STATIC_DRAW);
moonVertexTextureCoordBuffer.itemSize = 2;
moonVertexTextureCoordBuffer.numItems = textureCoordData.length / 2;

moonVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(vertexPositionData), gl.STATIC_DRAW);
moonVertexPositionBuffer.itemSize = 3;
moonVertexPositionBuffer.numItems = vertexPositionData.length / 3;

moonVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, moonVertexIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array(indexData), gl.STATIC_DRAW);
moonVertexIndexBuffer.itemSize = 1;
moonVertexIndexBuffer.numItems = indexData.length;

laptopScreenVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, laptopScreenVertexPositionBuffer);
vertices = [
0.580687, 0.659, 0.813106,
-0.580687, 0.659, 0.813107,
0.580687, 0.472, 0.113121,
-0.580687, 0.472, 0.113121,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
laptopScreenVertexPositionBuffer.itemSize = 3;
laptopScreenVertexPositionBuffer.numItems = 4;

laptopScreenVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, laptopScreenVertexNormalBuffer);
var vertexNormals = [
0.000000, -0.965926, 0.258819,
0.000000, -0.965926, 0.258819,
0.000000, -0.965926, 0.258819,
0.000000, -0.965926, 0.258819,
];
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(vertexNormals), gl.STATIC_DRAW);
laptopScreenVertexNormalBuffer.itemSize = 3;
laptopScreenVertexNormalBuffer.numItems = 4;

laptopScreenVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, laptopScreenVertexTextureCoordBuffer);
var textureCoords = [
1.0, 1.0,
0.0, 1.0,
1.0, 0.0,
0.0, 0.0,
];
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(textureCoords), gl.STATIC_DRAW);
laptopScreenVertexTextureCoordBuffer.itemSize = 2;
laptopScreenVertexTextureCoordBuffer.numItems = 4;
}
var laptopScreenAspectRatio = 1.66;

var moonAngle = 180;
var cubeAngle = 0;
function drawSceneOnLaptopScreen()
{
gl.viewport(0, 0, rttFramebuffer.width, rttFramebuffer.height);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

mat4.perspective(pMatrix, 45, laptopScreenAspectRatio, 0.1, 100.0);

gl.uniform1i(shaderProgram.showSpecularHighlightsUniform, false);
gl.uniform3f(shaderProgram.ambientLightingColorUniform, 0.2, 0.2, 0.2);
gl.uniform3f(shaderProgram.pointLightingLocationUniform, 0, 0, -5);
gl.uniform3f(shaderProgram.pointLightingDiffuseColorUniform, 0.8, 0.8, 0.8);

gl.uniform1i(shaderProgram.showSpecularHighlightsUniform, false);
gl.uniform1i(shaderProgram.useTexturesUniform, true);

gl.uniform3f(shaderProgram.materialAmbientColorUniform, 1.0, 1.0, 1.0);
gl.uniform3f(shaderProgram.materialDiffuseColorUniform, 1.0, 1.0, 1.0);
gl.uniform3f(shaderProgram.materialSpecularColorUniform, 0.0, 0.0, 0.0);
gl.uniform1f(shaderProgram.materialShininessUniform, 0);
gl.uniform3f(shaderProgram.materialEmissiveColorUniform, 0.0, 0.0, 0.0);

mat4.identity(mvMatrix);

mat4.translate(mvMatrix, mvMatrix, [0, 0, -5]);
mat4.rotate(mvMatrix, mvMatrix, degToRad(30), [1, 0, 0]);

mvPushMatrix();
mat4.rotate(mvMatrix, mvMatrix, degToRad(moonAngle), [0, 1, 0]);
mat4.translate(mvMatrix, mvMatrix, [2, 0, 0]);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, moonTexture);
gl.uniform1i(shaderProgram.samplerUniform, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute,
moonVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute,
moonVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute,
moonVertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, moonVertexIndexBuffer);
setMatrixUniforms();
gl.drawElements(gl.TRIANGLES,
moonVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
mvPopMatrix();


mvPushMatrix();
mat4.rotate(mvMatrix, mvMatrix, degToRad(cubeAngle), [0, 1, 0]);
mat4.translate(mvMatrix, mvMatrix, [1.25, 0, 0]);
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute,
cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute,
cubeVertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute,
cubeVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, crateTexture);
gl.uniform1i(shaderProgram.samplerUniform, 0);

gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
setMatrixUniforms();
gl.drawElements(gl.TRIANGLES,
cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
mvPopMatrix();

gl.bindTexture(gl.TEXTURE_2D, rttTexture);
gl.generateMipmap(gl.TEXTURE_2D);
gl.bindTexture(gl.TEXTURE_2D, null);
}
var laptopAngle = 0;

function drawScene()
{
gl.bindFramebuffer(gl.FRAMEBUFFER, rttFramebuffer);
drawSceneOnLaptopScreen();
gl.bindFramebuffer(gl.FRAMEBUFFER, null);

gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

mat4.perspective(pMatrix, 45,
gl.viewportWidth / gl.viewportHeight, 0.1, 100.0);

mat4.identity(mvMatrix);

mvPushMatrix();

mat4.translate(mvMatrix, mvMatrix, [0, -0.4, -2.2]);
mat4.rotate(mvMatrix, mvMatrix, degToRad(laptopAngle), [0, 1, 0]);
mat4.rotate(mvMatrix, mvMatrix, degToRad(-90), [1, 0, 0]);

gl.uniform1i(shaderProgram.showSpecularHighlightsUniform, true);
gl.uniform3f(shaderProgram.pointLightingLocationUniform, -1, 2, -1);
gl.uniform3f(shaderProgram.ambientLightingColorUniform, -1, 2, -1);

gl.uniform3f(shaderProgram.ambientLightingColorUniform, 0.2, 0.2, 0.2);
gl.uniform3f(shaderProgram.pointLightingDiffuseColorUniform, 0.8, 0.8, 0.8);
gl.uniform3f(shaderProgram.pointLightingSpecularColorUniform, 0.8, 0.8, 0.8);


gl.uniform3f(shaderProgram.materialAmbientColorUniform, 1.0, 1.0, 1.0);
gl.uniform3f(shaderProgram.materialDiffuseColorUniform, 1.0, 1.0, 1.0);
gl.uniform3f(shaderProgram.materialSpecularColorUniform, 1.5, 1.5, 1.5);
gl.uniform1f(shaderProgram.materialShininessUniform, 5);
gl.uniform3f(shaderProgram.materialEmissiveColorUniform, 0.0, 0.0, 0.0);
gl.uniform1i(shaderProgram.useTexturesUniform, false);

if (laptopVertexPositionBuffer)
{
gl.bindBuffer(gl.ARRAY_BUFFER, laptopVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute,
laptopVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, laptopVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute,
laptopVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, laptopVertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute,
laptopVertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, laptopVertexIndexBuffer);
setMatrixUniforms();
gl.drawElements(gl.TRIANGLES,
laptopVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
}

gl.uniform3f(shaderProgram.materialAmbientColorUniform, 0.0, 0.0, 0.0);
gl.uniform3f(shaderProgram.materialDiffuseColorUniform, 0.0, 0.0, 0.0);
gl.uniform3f(shaderProgram.materialSpecularColorUniform, 0.5, 0.5, 0.5);
gl.uniform1f(shaderProgram.materialShininessUniform, 20);
gl.uniform3f(shaderProgram.materialEmissiveColorUniform, 1.5, 1.5, 1.5);
gl.uniform1i(shaderProgram.useTexturesUniform, true);

gl.bindBuffer(gl.ARRAY_BUFFER, laptopScreenVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute,
laptopScreenVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, laptopScreenVertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute,
laptopScreenVertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.bindBuffer(gl.ARRAY_BUFFER, laptopScreenVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute,
laptopScreenVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, rttTexture);
gl.uniform1i(shaderProgram.samplerUniform, 0);

setMatrixUniforms();
gl.drawArrays(gl.TRIANGLE_STRIP, 0,
laptopScreenVertexPositionBuffer.numItems);

mvPopMatrix();
}

function degToRad(degrees)
{
return degrees * Math.PI / 180;
}
var lastTime = 0;
function animate()
{
var timeNow = new Date().getTime();
if(lastTime != 0)
{
var elapsed = timeNow - lastTime;

moonAngle += 0.05 * elapsed;
cubeAngle += 0.05 * elapsed;

laptopAngle -= 0.005 * elapsed;
}
lastTime = timeNow;
}
</script>
```