三十二课代码（WebGL课程代码专用）文件列表 index.html grid_object.js logic.js i

文件列表

index.html
grid_object.js
logic.js
image.js
images/funny-cat.jpeg

index.html

<!doctype html>
<html>

<head>
    <style>
        canvas {
            border: 1px solid #000000;
        }
    </style>

</head>

<body>

    <canvas id="tri" width="300" height="300" style="width:300px; height:300px">
    </canvas>
    <script id="vertex_shader" type="myshader">
        // Vertex Shader
        precision mediump int;
        precision mediump float;
        
        uniform mat3 u_all;
        attribute vec2 a_PointVertex; // 顶点坐标
        attribute vec2 a_PointUV; // 顶点坐标

        varying vec2 uv;
        varying vec2 pos;

        void main() {
          vec3 coord = u_all * vec3(a_PointVertex, 1.0);
          gl_Position = vec4(coord.x, coord.y, 0.0, 1.0);
          uv = a_PointUV;
          uv.y = 1.0 - uv.y;
          pos = coord.xy;
        }
    </script>
    <script id="fragment_shader" type="myshader">
        // Fragment shader
        precision mediump int;
        precision mediump float;

        uniform sampler2D u_funny_cat; // 有趣的猫的图片
        uniform vec2 u_lightPos;         // 光源的位置

        varying vec2 uv;
        varying vec2 pos;

        void main() {
            vec4 sample_color = texture2D(u_funny_cat, uv);
            float light = 1.0 - distance(pos, u_lightPos);
            sample_color.x  = sample_color.x * light;
            sample_color.y  = 0.0;
            sample_color.z  = 0.0;
            
            gl_FragColor = vec4(sample_color.xyz, 1.0);
        }
    </script>
    <script type="text/javascript" src="image.js"></script>
    <script type="text/javascript" src="grid_object.js"></script>
    <script type="text/javascript" src="logic.js"></script>
</body>

</html>

image.js

var images_loaing_ok = false;

function isPowerOf2(value) {
    return (value & (value - 1)) === 0;
}

function CreateTextureAndLoadImage(gl, loading_callback) {
    // 在 WebGL 里创建一个 texture
    let texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, texture);

    // 异步加载一张图片，存进刚刚创建好的 texture 里
    var image = new Image();
    image.src = "images/funny-cat.jpeg";
    image.addEventListener('load', function () {
        // gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, texture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
        if (isPowerOf2(image.width) && isPowerOf2(image.height)) {
            gl.generateMipmap(gl.TEXTURE_2D);
        } else {
            console.log("image loading , not Power of 2");
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
        }
        images_loaing_ok = true;
        loading_callback();
    });
    return;
}

grid_object.js

class GridObject {
    // 宽 高 x坐标 y坐标
    // 中心点是基准点
    constructor(scalex, scaley, posx, posy) {
        this.scalex = scalex;
        this.scaley = scaley;
        this.posx = posx;
        this.posy = posy;
        this.modelUpdated = false; // 模型是否更新，也就是说，是否需要重新绘制
        this.glbuffer = null;
        this.a_PointVertex = null;
        this.a_PointUV = null;
        this.rotate = 0;
    }
    // 生成模型数据
    // 六个点 两个三角形
    genData(gl) {
        this.data = [
            // 第一个三角形
            -1, -1, 0, 0, // 左下角点
            1, -1, 1, 0, // 右下角点
            1, 1, 1, 1, // 右上角点
            // 第二个三角形
            1, 1, 1, 1,  // 右上角点
            -1, 1, 0, 1,  // 左上角点
            -1, -1, 0, 0,  // 左下角点
        ];
        this.dataArr = new Float32Array(this.data);
        this.pointCount = 6; // 一个格子固定六个点 两个三角形

        if (this.glbuffer != null) { // 先删掉原来的buffer
            gl.deleteBuffer(this.glbuffer);
            this.a_PointVertex = null;
        }
        this.glbuffer = gl.createBuffer(); // 在创建新的buffer
        gl.bindBuffer(gl.ARRAY_BUFFER, this.glbuffer);
        gl.bufferData(gl.ARRAY_BUFFER, this.dataArr, gl.STATIC_DRAW);
        this.modelUpdated = true;
    }
    render(gl, program) {
        gl.bindBuffer(gl.ARRAY_BUFFER, this.glbuffer);
        if (this.modelUpdated) {
            this.modelUpdated = false;
            if (this.a_PointVertex == null) {
                this.a_PointVertex = gl.getAttribLocation(program, 'a_PointVertex');
            }
            if (this.a_PointUV == null) {
                this.a_PointUV = gl.getAttribLocation(program, 'a_PointUV');
            }
        }
        //////////////////////////
        gl.vertexAttribPointer(this.a_PointVertex, 2, gl.FLOAT, false, 16, 0); // 坐标
        gl.enableVertexAttribArray(this.a_PointVertex);
        gl.vertexAttribPointer(this.a_PointUV, 2, gl.FLOAT, false, 16, 8); // UV
        gl.enableVertexAttribArray(this.a_PointUV);
        //
        let rad = ((2 * Math.PI) / 360) * this.rotate;
        gl.uniformMatrix3fv(u_all_loc, false, genMat3ForGL(this.scalex,
            this.scaley, rad, this.posx, this.posy
        ));
        gl.drawArrays(gl.TRIANGLES, 0, this.pointCount);
    }
}

logic.js

var pointCanvas = null;
var gl = null;

var u_all_loc = null;
var u_color = null;

var gridList = [];

var program = null;


// 入口函数
function Main() {
    gl_init();
    generateGrid(gl);
    CreateTextureAndLoadImage(gl, gl_draw);
}

function genMat3ForGL(a, b, alpha, A, B) {
    let mat3 = [
        a * Math.cos(alpha), a * Math.sin(alpha), 0,
        -b * Math.sin(alpha), b * Math.cos(alpha), 0,
        A, B, 1,
    ];
    return new Float32Array(mat3);
}

// 生成背景格子
function generateGrid(gl) {
    //////////////////////////
    let digit0 = new GridObject(1, 1, 0, 0);
    gridList.push(digit0);
    gridList.forEach(element => {
        element.genData(gl);
    });
}

function gl_init() {
    pointCanvas = document.getElementById('tri'); // 我们的纸
    pointCanvas.addEventListener("click", function __handler__(evt) {
        let x = evt.clientX;
        let y = evt.clientY;
        let rect = pointCanvas.getBoundingClientRect();
        x -= rect.left;
        y -= rect.top;
        x -= pointCanvas.width / 2;
        x /= pointCanvas.width / 2;
        y = pointCanvas.height - y;
        y -= pointCanvas.height / 2;
        y /= pointCanvas.height / 2;
        //
        gl.uniform2f(u_lightPos, x, y);
        gl_draw();
    });

    gl = pointCanvas.getContext('webgl', { preserveDrawingBuffer: true }); // 我们的笔

    var vertex_shader_code = document.getElementById('vertex_shader').textContent;

    var vertex_shader = gl.createShader(gl.VERTEX_SHADER);
    gl.shaderSource(vertex_shader, vertex_shader_code);
    gl.compileShader(vertex_shader);
    // 检查shader错误
    const v_compiled = gl.getShaderParameter(vertex_shader, gl.COMPILE_STATUS);
    if (!v_compiled) {
        const v_theError = gl.getShaderInfoLog(vertex_shader);
        console.error(v_theError);
        gl.deleteShader(vertex_shader);
    }

    //
    var fragment_shader_code = document.getElementById('fragment_shader').textContent;
    var fragment_shader = gl.createShader(gl.FRAGMENT_SHADER);
    gl.shaderSource(fragment_shader, fragment_shader_code);
    gl.compileShader(fragment_shader);
    // 检查shader错误
    const f_compiled = gl.getShaderParameter(fragment_shader, gl.COMPILE_STATUS);
    if (!f_compiled) {
        const f_theError = gl.getShaderInfoLog(fragment_shader);
        console.error(f_theError);
        gl.deleteShader(fragment_shader);
    }
    //
    program = gl.createProgram();
    gl.attachShader(program, vertex_shader);
    gl.attachShader(program, fragment_shader);
    gl.linkProgram(program);
    gl.useProgram(program);

    uniforms_init(gl);
}

function uniforms_init(gl) {
    // uniforms
    u_all_loc = gl.getUniformLocation(program, "u_all");
    u_lightPos = gl.getUniformLocation(program, "u_lightPos");
}

// gl更新逻辑
function gl_draw() {

    gl.enable(gl.CULL_FACE);
    gl.enable(gl.DEPTH_TEST);

    gl.clearColor(0, 0, 0, 0);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);



    gridList.forEach(element => {
        element.render(gl, program);
    });

}

Main();