# 球、旋转矩阵、鼠标事件

```html
<div class="page-header"><h3>11、球、旋转矩阵、鼠标事件</h3></div>

<canvas id = "test11-canvas" width = "800" height = "600"></canvas>

<br/>
<input type="checkbox" id="lighting" checked /> 使用光照
<br/>
(鼠标拖拽对月球进行转动)
<br/>
<h4>方向光:</h4>
<table>
<tr>
<td><b>方向:</b></td>
<td>X: <input type="text" id="lightDirectionX" value="-0.25" /></td>
<td>Y: <input type="text" id="lightDirectionY" value="-0.25" /></td>
<td>Z: <input type="text" id="lightDirectionZ" value="-1.0" /></td>
</tr>
<tr>
<td><b>颜色:</b></td>
<td>R: <input type="text" id="directionalR" value="0.8" /></td>
<td>G: <input type="text" id="directionalG" value="0.8" /></td>
<td>B: <input type="text" id="directionalB" value="0.8" /></td>
</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="0.2" /></td>
<td>G: <input type="text" id="ambientG" value="0.2" /></td>
<td>B: <input type="text" id="ambientB" value="0.2" /></td>
</tr>
</table>
<br/>
月球表面纹理图片来自:
<a href="http://maps.jpl.nasa.gov/">the Jet Propulsion Laboratory</a>.
<script id = "shader-vs" type = "x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec3 aVertexNormal;
attribute vec2 aTextureCoord;

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

uniform vec3 uAmbientColor;

uniform vec3 uLightingDirection;
uniform vec3 uDirectionalColor;

uniform bool uUseLighting;

varying vec2 vTextureCoord;
varying vec3 vLightWeighting;

void main(void)
{
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vTextureCoord = aTextureCoord;

if(!uUseLighting)
{
vLightWeighting = vec3(1.0, 1.0, 1.0);
}
else
{
vec3 transformedNormal = uNMatrix * aVertexNormal;
float directionalLightWeighting =
max(dot(transformedNormal, uLightingDirection), 0.0);
vLightWeighting =
uAmbientColor + uDirectionalColor * directionalLightWeighting;
}
}
</script>

<script id = "shader-fs" type = "x-shader/x-fragment">
precision mediump float;
varying vec2 vTextureCoord;
varying vec3 vLightWeighting;

uniform sampler2D uSampler;
void main(void)
{
vec4 textureColor =
texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
gl_FragColor =
vec4(textureColor.rgb * vLightWeighting, textureColor.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 = $("#test11-canvas");
initGL(canvas[0]);
initShaders();
initBuffers();
initTexture();

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

canvas.mousedown(handleMouseDown);
$(document).mouseup(handleMouseUp);
$(document).mousemove(handleMouseMove);
}
function tick()
{
requestAnimFrame(tick);
drawScene();
}
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 moonTexture;
function initTexture()
{
moonTexture = gl.createTexture();
moonTexture.image = new Image();
moonTexture.image.onload = function()
{
handleLoadedTexture(moonTexture);
tick();
}
moonTexture.image.src = "/Public/image/moon.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 fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");

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.useLightingUniform =
gl.getUniformLocation(shaderProgram, "uUseLighting");
shaderProgram.ambientColorUniform =
gl.getUniformLocation(shaderProgram, "uAmbientColor");
shaderProgram.lightingDirectionUniform =
gl.getUniformLocation(shaderProgram, "uLightingDirection");
shaderProgram.directionalColorUniform =
gl.getUniformLocation(shaderProgram, "uDirectionalColor");
}


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 mouseDown = false;
var lastMouseX = null;
var lastMouseY = null;
var moonRotationMatrix = mat4.create();
mat4.identity(moonRotationMatrix);
function handleMouseDown(event)
{
mouseDown = true;
lastMouseX = event.clientX;
lastMouseY = event.clientY;
}
function handleMouseUp(event)
{
mouseDown = false;
}
function handleMouseMove(event)
{
if(!mouseDown)
{
return;
}
var newX = event.clientX;
var newY = event.clientY;
var newRotationMatrix = mat4.create();
mat4.identity(newRotationMatrix);

var deltaX = newX - lastMouseX;
mat4.rotate(newRotationMatrix, newRotationMatrix,
degToRad(deltaX / 10), [0, 1, 0]);
var deltaY = newY - lastMouseY;
mat4.rotate(newRotationMatrix, newRotationMatrix,
degToRad(deltaY / 10), [1, 0, 0]);

mat4.multiply(moonRotationMatrix, newRotationMatrix, moonRotationMatrix);

lastMouseX = newX;
lastMouseY = newY;
}
function equal(a, b)
{
for(var i = 0; i < a.length; i ++)
if(a[i] != b[i]) return false;
return true;
}
var moonVertexPositionBuffer;
var moonVertexNormalBuffer;
var moonVertexTextureCoordBuffer;
var moonVertexIndexBuffer;

function initBuffers()
{
var latitudeBands = 30;
var longitudeBands = 30;
var radius = 2;
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;
}
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 lighting = $("#lighting").is(":checked");
gl.uniform1i(shaderProgram.useLightingUniform, lighting);
if(lighting)
{
gl.uniform3f(
shaderProgram.ambientColorUniform,
parseFloat($("#ambientR").val()),
parseFloat($("#ambientG").val()),
parseFloat($("#ambientB").val())
);
var lightingDirection = [
parseFloat($("#lightDirectionX").val()),
parseFloat($("#lightDirectionY").val()),
parseFloat($("#lightDirectionZ").val())
];
var adjustedLD = vec3.create();
vec3.normalize(adjustedLD, lightingDirection);
vec3.scale(adjustedLD, adjustedLD, -1);
gl.uniform3fv(shaderProgram.lightingDirectionUniform, adjustedLD);
gl.uniform3f(
shaderProgram.directionalColorUniform,
parseFloat($("#directionalR").val()),
parseFloat($("#directionalG").val()),
parseFloat($("#directionalB").val())
);
}

mat4.identity(mvMatrix);
mat4.translate(mvMatrix, mvMatrix, [0, 0, -6]);

mat4.multiply(mvMatrix, mvMatrix, moonRotationMatrix);

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

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

gl.bindBuffer(gl.ARRAY_BUFFER, moonVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute,
moonVertexPositionBuffer.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);
}

function degToRad(degrees)
{
return degrees * Math.PI / 180;
}
</script>
```