二十九课代码（WebGL课程代码专用）二十九课代码，本代码使用与专栏第二十九课内容。读者自行复制到本地用任意http服务

文件列表

index.html
grid_object.js
logic.js

index.html


<!doctype html>
<html>

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

</head>

<body>
    <p>
        <b>第一个格子的颜色:</b>
        <input id="gridcolor" type="range" min="0" max="1" value="0" step="0.05" oninput="gl_draw()" />
        <b id="gridcolorvalue">0</b>
    </p>

    <canvas id="tri" width="600" height="600" 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 float a_Color;        // 顶点颜色 我们只用 黑色 和 白色 所以这里float足够了
        varying float v_color;        // 传递给 fragment_shader
        void main() {
          vec3 coord = u_all * vec3(a_PointVertex, 1.0);
          gl_Position = vec4(coord.x, coord.y, 0.0, 1.0);
          v_color = a_Color;
        }
    </script>
    <script id="fragment_shader" type="myshader">
        // Fragment shader
        precision mediump int;
        precision mediump float;

        varying float v_color;        // 接收来自 vertex_shader 的颜色

        void main() {
          gl_FragColor = vec4(v_color, v_color, v_color, 1.0);
        }
    </script>
    <script type="text/javascript" src="grid_object.js"></script>
    <script type="text/javascript" src="logic.js"></script>
</body>

</html>

grid_object.js


class GridObject {
    // 宽 高 x坐标 y坐标
    // 左下角为基准点
    constructor(width, height, posx, posy, color) {
        this.width = width;
        this.height = height;
        this.posx = posx;
        this.posy = posy;
        this.color = color;
        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_Color = null;
    }
    // 生成模型数据
    // 六个点 两个三角形
    genData(gl) {
        this.data = [
            // 第一个三角形
            this.posx, this.posy, this.color, // 左下角点
            this.posx + this.width, this.posy, this.color, // 右下角点
            this.posx + this.width, this.posy + this.height, this.color, // 右上角点
            // 第二个三角形
            this.posx + this.width, this.posy + this.height, 1 - this.color, // 右上角点
            this.posx, this.posy + this.height, 1 - this.color, // 左上角点
            this.posx, this.posy, 1 - this.color, // 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.a_Color = 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_Color == null) {
                this.a_Color = gl.getAttribLocation(program, 'a_Color');
            }
        }
        //////////////////////////
        gl.vertexAttribPointer(this.a_PointVertex, 2, gl.FLOAT, false, 12, 0);
        gl.vertexAttribPointer(this.a_Color, 1, gl.FLOAT, false, 12, 8);
        gl.enableVertexAttribArray(this.a_Color);
        gl.enableVertexAttribArray(this.a_PointVertex);
        gl.drawArrays(gl.TRIANGLES, 0, this.pointCount);
    }
}

logic.js

var pointCanvas = null;
var gl = null;

var u_all_loc = null;


var gridColorDom = null;
var gridColorValueDom = null;


var gridOne = null;
var gridTwo = null;
var program = null;


// 入口函数
function Main() {
    gl_init();
    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);
}

function gl_init() {
    pointCanvas = document.getElementById('tri'); // 我们的纸
    gl = pointCanvas.getContext('webgl', { preserveDrawingBuffer: true }); // 我们的笔

    gridOne = new GridObject(0.5, 0.5, 0, 0, 0.3);
    gridOne.genData(gl);

    gridTwo = new GridObject(0.5, 0.5, -0.5, -0.5, 0.3);
    gridTwo.genData(gl);

    // data = [-1, -1, 0, 0,
    //     1, -1, 1, 0,
    //     0, 1, 0.5, 1
    // ];

    // dataArr = new Float32Array(data);
    // pointCount = 3;

    // buffer_point = gl.createBuffer();
    // gl.bindBuffer(gl.ARRAY_BUFFER, buffer_point);
    // gl.bufferData(gl.ARRAY_BUFFER, dataArr, gl.STATIC_DRAW);

    //
    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);
    // attributes
    // var a_PointVertex = gl.getAttribLocation(program, 'a_PointVertex');

    // gl.vertexAttribPointer(a_PointVertex, 2, gl.FLOAT, false, 16, 0);
    // gl.enableVertexAttribArray(a_PointVertex);

    // uniforms
    u_all_loc = gl.getUniformLocation(program, "u_all");

    gridColorDom = document.getElementById("gridcolor");
    gridColorValueDom = document.getElementById("gridcolorvalue");


}

// gl更新逻辑
function gl_draw() {

    gl.uniformMatrix3fv(u_all_loc, false, genMat3ForGL(1,
        1, 0, 0, 0
    ));

    gridColorValueDom.innerText = gridColorDom.value;


    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);

    gridOne.color = gridColorDom.value;
    gridOne.genData(gl);
    gridOne.render(gl, program);
    gridTwo.render(gl, program);
}

Main();