# 镜面地图

```html
<div class="page-header"><h3>15、镜面地图</h3></div>

<canvas id = "test15-canvas" width = "800" height = "600"></canvas>
<br/>
<input type="checkbox" id="color-map" checked /> 使用纹理
<br/>
<input type="checkbox" id="specular-map" checked /> 使用高光标记图
<br/>
<input type="checkbox" id="lighting" checked /> 使用光照
<br/>

<h4>点光:</h4>
<table>
<tr>
<td><b>位置:</b></td>
<td>X: <input type="text" id="lightPositionX" value="-10.0" />
</td>
<td>Y: <input type="text" id="lightPositionY" value="4.0" /></td>
<td>Z: <input type="text" id="lightPositionZ" value="-20.0" /></td>
</tr>
<tr>
<td><b>镜面反射颜色:</b></td>
<td>R: <input type="text" id="specularR" value="5.0" /></td>
<td>G: <input type="text" id="specularG" value="5.0" /></td>
<td>B: <input type="text" id="specularB" value="5.0" /></td>
</tr>
<tr>
<td><b>漫反射颜色:</b>
<td>R: <input type="text" id="diffuseR" value="0.8" />
<td>G: <input type="text" id="diffuseG" value="0.8" />
<td>B: <input type="text" id="diffuseB" value="0.8" />
</tr>
</table>
<h4>环境光:</h4>
<table style="border: 0; padding: 10px;">
<tr>
<td><b>颜色:</b></td>
<td>R: <input type="text" id="ambientR" value="0.4" /></td>
<td>G: <input type="text" id="ambientG" value="0.4" /></td>
<td>B: <input type="text" id="ambientB" value="0.4" /></td>
</tr>
</table>
<br/>
地球纹理来自:
<a href="http://www.esa.int/esaEO/SEMGSY2IU7E_index_0.html">
the European Space Agency/Envisat
</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 bool uUseColorMap;
uniform bool uUseSpecularMap;
uniform bool uUseLighting;

uniform vec3 uAmbientColor;

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

uniform sampler2D uColorMapSampler;
uniform sampler2D uSpecularMapSampler;


void main(void)
{
vec3 lightWeighting;
if (!uUseLighting)
{
lightWeighting = vec3(1.0, 1.0, 1.0);
}
else
{
vec3 lightDirection =
normalize(uPointLightingLocation - vPosition.xyz);
vec3 normal = normalize(vTransformedNormal);

float specularLightWeighting = 0.0;
float shininess = 32.0;
if (uUseSpecularMap)
{
shininess =
texture2D(uSpecularMapSampler,
vec2(vTextureCoord.s, vTextureCoord.t)).r * 255.0;
}
if (shininess < 255.0)
{
vec3 eyeDirection = normalize(-vPosition.xyz);
vec3 reflectionDirection = reflect(-lightDirection, normal);

specularLightWeighting =
pow(max(dot(reflectionDirection, eyeDirection), 0.0),
shininess);
}

float diffuseLightWeighting = max(dot(normal, lightDirection), 0.0);
lightWeighting = uAmbientColor +
uPointLightingSpecularColor * specularLightWeighting +
uPointLightingDiffuseColor * diffuseLightWeighting;
}

vec4 fragmentColor;
if (uUseColorMap)
{
fragmentColor =
texture2D(uColorMapSampler,
vec2(vTextureCoord.s, vTextureCoord.t));
}
else
{
fragmentColor = vec4(1.0, 1.0, 1.0, 1.0);
}
gl_FragColor = vec4(fragmentColor.rgb * lightWeighting, fragmentColor.a);
}
</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 = $("#test15-canvas");
initGL(canvas[0]);
initShaders();
initTextures();
initBuffers();

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

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

var textureFlag = [0, 0];
var startTick = false;
var waitTick;
function tick()
{
if(textureFlag[0] == 1 && textureFlag[1] == 1)
{
startTick = true;
textureFlag[0] = 2;
textureFlag[1] = 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 earthColorMapTexture;
var earthSpecularMapTexture;
function initTextures()
{
earthColorMapTexture = gl.createTexture();
earthColorMapTexture.image = new Image();
earthColorMapTexture.image.onload = function ()
{
handleLoadedTexture(earthColorMapTexture)
textureFlag[0] = true;
}
earthColorMapTexture.image.src = "/Public/image/earth.jpg";

earthSpecularMapTexture = gl.createTexture();
earthSpecularMapTexture .image = new Image();
earthSpecularMapTexture .image.onload = function ()
{
handleLoadedTexture(earthSpecularMapTexture)
textureFlag[1] = true;
}
earthSpecularMapTexture .image.src = "/Public/image/earth-specular.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.colorMapSamplerUniform =
gl.getUniformLocation(shaderProgram, "uColorMapSampler");
shaderProgram.specularMapSamplerUniform =
gl.getUniformLocation(shaderProgram, "uSpecularMapSampler");
shaderProgram.useColorMapUniform =
gl.getUniformLocation(shaderProgram, "uUseColorMap");
shaderProgram.useSpecularMapUniform =
gl.getUniformLocation(shaderProgram, "uUseSpecularMap");
shaderProgram.useLightingUniform =
gl.getUniformLocation(shaderProgram, "uUseLighting");
shaderProgram.ambientColorUniform =
gl.getUniformLocation(shaderProgram, "uAmbientColor");
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 sphereVertexPositionBuffer;
var sphereVertexNormalBuffer;
var sphereVertexTextureCoordBuffer;
var sphereVertexIndexBuffer;

function initBuffers()
{
var latitudeBands = 30;
var longitudeBands = 30;
var radius = 13;

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);
}
}
sphereVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, sphereVertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(normalData), gl.STATIC_DRAW);
sphereVertexNormalBuffer.itemSize = 3;
sphereVertexNormalBuffer.numItems = normalData.length / 3;

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

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

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

var earthAngle = 180;

function drawScene()
{
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);

var useColorMap = $("#color-map").is(":checked");
gl.uniform1i(shaderProgram.useColorMapUniform, useColorMap);

var useSpecularMap = $("#specular-map").is(":checked");
gl.uniform1i(shaderProgram.useSpecularMapUniform, useSpecularMap );

var lighting = $("#lighting").is(":checked");
gl.uniform1i(shaderProgram.useLightingUniform, lighting);
if(lighting)
{
gl.uniform3f(
shaderProgram.ambientColorUniform,
parseFloat($("#ambientR").val()),
parseFloat($("#ambientG").val()),
parseFloat($("#ambientB").val())
);
gl.uniform3f(
shaderProgram.pointLightingLocationUniform,
parseFloat($("#lightPositionX").val()),
parseFloat($("#lightPositionY").val()),
parseFloat($("#lightPositionZ").val())
);

gl.uniform3f(
shaderProgram.pointLightingSpecularColorUniform,
parseFloat($("#specularR").val()),
parseFloat($("#specularG").val()),
parseFloat($("#specularB").val())
);

gl.uniform3f(
shaderProgram.pointLightingDiffuseColorUniform,
parseFloat($("#diffuseR").val()),
parseFloat($("#diffuseG").val()),
parseFloat($("#diffuseB").val())
);

}

mat4.identity(mvMatrix);
mat4.translate(mvMatrix, mvMatrix, [0, 0, -40]);
mat4.rotate(mvMatrix, mvMatrix, degToRad(23.4), [1, 0, -1]);
mat4.rotate(mvMatrix, mvMatrix, degToRad(earthAngle), [0, 1, 0]);

gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, earthColorMapTexture);
gl.uniform1i(shaderProgram.specularMapSamplerUniform, 0);

gl.activeTexture(gl.TEXTURE1);
gl.bindTexture(gl.TEXTURE_2D, earthSpecularMapTexture);
gl.uniform1i(shaderProgram.specularMapSamplerUniform, 1);

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

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

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

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

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;

earthAngle += 0.05 * elapsed;
}
lastTime = timeNow;
}
</script>
```