微信小程序webgl 显示图片

// wxml<view class="container"><!-- 加载地图容器 --><canvas type="webgl" id="testMap" style="width: 100%; height: 100%;" disable-scroll bindtouchstart="touchStart" bindtouchmove="touchMove" bindtouchend="touchEnd"></canvas></view>

Page({
  data:{},/**
   * 生命周期函数--监听页面初次渲染完成
   */onReady(){
    wx.createSelectorQuery().select('#testMap').fields({ node:true, size:true}).exec((res)=>{
        let textCanvas = res[0].node;// 重点1

        let gl = textCanvas.getContext('webgl');// 重点2const vsSource = `
 attribute vec4 aVertexPosition;
 attribute vec2 aTextureCoord;
 varying highp vec2 vTextureCoord;voidmain(void){
     gl_Position = aVertexPosition;
     vTextureCoord = aTextureCoord;}
`;// Fragment shader source codeconst fsSource = `
     varying highp vec2 vTextureCoord;
     uniform sampler2D uSampler;voidmain(void){

     gl_FragColor =texture2D(uSampler,vec2(vTextureCoord.x,1.0-vTextureCoord.y));}
`;// Initialize shaders
        function initShaderProgram(gl, vsSource, fsSource){const vertexShader =loadShader(gl, gl.VERTEX_SHADER, vsSource);const fragmentShader =loadShader(gl, gl.FRAGMENT_SHADER, fsSource);const shaderProgram = gl.createProgram();
          gl.attachShader(shaderProgram, vertexShader);
          gl.attachShader(shaderProgram, fragmentShader);
          gl.linkProgram(shaderProgram);if(!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)){alert('Unable to initialize the shader program: ' + gl.getProgramInfoLog(shaderProgram));return null;}return shaderProgram;}

        function loadShader(gl, type, source){const shader = gl.createShader(type);
          gl.shaderSource(shader, source);
          gl.compileShader(shader);if(!gl.getShaderParameter(shader, gl.COMPILE_STATUS)){alert('An error occurred compiling the shaders: ' + gl.getShaderInfoLog(shader));
            gl.deleteShader(shader);return null;}return shader;}const shaderProgram =initShaderProgram(gl, vsSource, fsSource);const programInfo ={
          program: shaderProgram,
          attribLocations:{
            vertexPosition: gl.getAttribLocation(shaderProgram,'aVertexPosition'),
            textureCoord: gl.getAttribLocation(shaderProgram,'aTextureCoord'),},
          uniformLocations:{
            uSampler: gl.getUniformLocation(shaderProgram,'uSampler'),},};// Initialize buffersconst positionBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);const positions =[-1.0,1.0,1.0,1.0,-1.0,-1.0,1.0,-1.0,];
        gl.bufferData(gl.ARRAY_BUFFER,newFloat32Array(positions), gl.STATIC_DRAW);const textureCoordBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, textureCoordBuffer);const textureCoordinates =[0.0,0.0,1.0,0.0,0.0,1.0,1.0,1.0,];
        gl.bufferData(gl.ARRAY_BUFFER,newFloat32Array(textureCoordinates), gl.STATIC_DRAW);// Load texture
        function loadTexture(gl, cb){const texture = gl.createTexture();
          gl.bindTexture(gl.TEXTURE_2D, texture);const level =0;const internalFormat = gl.RGBA;const srcFormat = gl.RGBA;const srcType = gl.UNSIGNED_BYTE;const image = textCanvas.createImage();
          image.onload =function(){
            gl.bindTexture(gl.TEXTURE_2D, texture);
            gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL,true);
            gl.texImage2D(gl.TEXTURE_2D, level, internalFormat, srcFormat, srcType, image);

            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);cb();};
          image.src = 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pyO1Yy/UA7eJotpQBkgNR4Gd4TDGnwWDVn/AOdLCf8APn+M5z/PnPn+f+efdxzMqjVRYK0pIA8qiKJMEYEpq1n27KEz1iOYW+/bZEzyXLyiZkYGBxOvWnoiq1xmgbb70LIpkYtWa9Oq90dpmYJiKFRZRHA8IGYiCkpJxxxyXqJpxxxw0accccNGnHHHDRpxxxw0accccNGv/9k=';return texture;}const texture =loadTexture(gl,()=>{render();});// Draw the scene
        function drawScene(gl, programInfo, buffers, texture){
          gl.clearColor(0.0,0.0,0.0,1.0);
          gl.clear(gl.COLOR_BUFFER_BIT);

          gl.useProgram(programInfo.program);

          gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
          gl.vertexAttribPointer(programInfo.attribLocations.vertexPosition,2, gl.FLOAT,false,0,0);
          gl.enableVertexAttribArray(programInfo.attribLocations.vertexPosition);

          gl.bindBuffer(gl.ARRAY_BUFFER, textureCoordBuffer);
          gl.vertexAttribPointer(programInfo.attribLocations.textureCoord,2, gl.FLOAT,false,0,0);
          gl.enableVertexAttribArray(programInfo.attribLocations.textureCoord);

          gl.activeTexture(gl.TEXTURE0);
          gl.bindTexture(gl.TEXTURE_2D, texture);
          gl.uniform1i(programInfo.uniformLocations.uSampler,0);

          gl.drawArrays(gl.TRIANGLE_STRIP,0,4);}

        function render(){drawScene(gl, programInfo,{ position: positionBuffer, textureCoord: textureCoordBuffer }, texture);}render();})},})

最后效果: