镜面高光

<div class="page-header"><h3>14、镜面高光</h3></div>

<canvas id = "test14-canvas" width = "800" height = "600"></canvas>
<br/>
<div id="loadingtext">正在加载数据...</div>
<br/>
<input type="checkbox" id="specular" checked /> 显示镜面高光
<br/>
<input type="checkbox" id="lighting" checked /> 使用光照
<br/>
<h4>纹理：</h4>
<select id="texture">
    <option value="none">无</option>
    <option selected value="galvanized">镀锌</option>
    <option value="earth">地球</option>
</select>
<br/>
<h4>材质：</h4>
<table style="border: 0; padding: 10px;">
    <tr>
        <td><b>Shininess:</b></td>
        <td><input type="text" id="shininess" value="32.0" /></td>
    </tr>
</table>
<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="0.8" /></td>
        <td>G: <input type="text" id="specularG" value="0.8" /></td>
        <td>B: <input type="text" id="specularB" value="0.8" /></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="0.2" /></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/>
镀锌纹理来自： 
<a href="http://www.arroway-textures.com/">
    Arroway Textures
</a>.
<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 float uMaterialShininess;
    uniform bool uShowSpecularHighlights;

    uniform bool uUseLighting;
    uniform bool uUseTextures;

    uniform vec3 uAmbientColor;

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

    uniform sampler2D uSampler;

    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;

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

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

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

        vec4 fragmentColor;
        if (uUseTextures)
        {
            fragmentColor =
                texture2D(uSampler, 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 = $("#test14-canvas");
    initGL(canvas[0]);
    initShaders();
    initTextures();

    loadTeapot();

    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 earthTexture;
var galvanizedTexture;
function initTextures()
{
    earthTexture = gl.createTexture();
    earthTexture.image = new Image();
    earthTexture.image.onload = function ()
    {
        handleLoadedTexture(earthTexture)
        textureFlag[0] = true;
    }
    earthTexture.image.src = "/Public/image/earth.jpg";

    galvanizedTexture = gl.createTexture();
    galvanizedTexture.image = new Image();
    galvanizedTexture.image.onload = function ()
    {
        handleLoadedTexture(galvanizedTexture)
        textureFlag[1] = true;
    }
    galvanizedTexture.image.src = 
        "/Public/image/arroway.de_metal+structure+06_d100_flat.jpg";
}
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.materialShininessUniform = 
        gl.getUniformLocation(shaderProgram, "uMaterialShininess");
    shaderProgram.showSpecularHighlightsUniform = 
        gl.getUniformLocation(shaderProgram, "uShowSpecularHighlights");
    shaderProgram.useTexturesUniform = 
        gl.getUniformLocation(shaderProgram, "uUseTextures");
    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 teapotVertexPositionBuffer;
var teapotVertexNormalBuffer;
var teapotVertexTextureCoordBuffer;
var teapotVertexIndexBuffer;
function loadTeapot()
{
    $.getJSON(
        "/Public/json/Teapot.json", 
        function(data)
        {
            handleLoadedTeapot(data);
        }
    );
}
function handleLoadedTeapot(teapotData)
{
    teapotVertexNormalBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexNormalBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, 
        new Float32Array(teapotData.vertexNormals), gl.STATIC_DRAW);
    teapotVertexNormalBuffer.itemSize = 3;
    teapotVertexNormalBuffer.numItems = 
        teapotData.vertexNormals.length / 3;
    teapotVertexTextureCoordBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexTextureCoordBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, 
        new Float32Array(teapotData.vertexTextureCoords), gl.STATIC_DRAW);
    teapotVertexTextureCoordBuffer.itemSize = 2;
    teapotVertexTextureCoordBuffer.numItems = 
        teapotData.vertexTextureCoords.length / 2;

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

    teapotVertexIndexBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, teapotVertexIndexBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, 
        new Uint16Array(teapotData.indices), gl.STATIC_DRAW);
    teapotVertexIndexBuffer.itemSize = 1;
    teapotVertexIndexBuffer.numItems = 
        teapotData.indices.length;

    $("#loadingtext").text("");
}

var teapotAngle = 180;

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

    if (teapotVertexPositionBuffer == null || 
        teapotVertexNormalBuffer == null || 
        teapotVertexTextureCoordBuffer == null || 
        teapotVertexIndexBuffer == null) 
    {
        return;
    }

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

    var specularHighlights = $("#specular").is(":checked");
    gl.uniform1i(shaderProgram.showSpecularHighlightsUniform, specularHighlights);

    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())
        );

    }

    var texture = $("#texture").val();
    gl.uniform1i(shaderProgram.useTexturesUniform, texture != "none");

    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(teapotAngle), [0, 1, 0]);

    gl.activeTexture(gl.TEXTURE0);
    if(texture == "earth")
    {
        gl.bindTexture(gl.TEXTURE_2D, earthTexture);
    }
    else if(texture == "galvanized")
    {
        gl.bindTexture(gl.TEXTURE_2D, galvanizedTexture);
    }
    gl.uniform1i(shaderProgram.samplerUniform, 0);
    gl.uniform1f(shaderProgram.materialShininessUniform, 
        parseFloat($("#shininess").val()));
    gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexTextureCoordBuffer);
    gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, 
        teapotVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

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

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

    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, teapotVertexIndexBuffer);
    setMatrixUniforms();
    gl.drawElements(gl.TRIANGLES, 
        teapotVertexIndexBuffer.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;

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