报一个 gl.pixelStorei 设置无效的 bug
https://developers.weixin.qq.com/miniprogram/dev/api/canvas/Canvas.getContext.html 在微信小程序电脑端,当进行 GL 设置纹理操作时, 发现设置垂直翻转的代码 “gl.pixelStorei (gl.UNPACK_FLIP_Y_WEBGL, true)” 无论设置为 true 还是 false 都不生效。 希望能尽快得到解决。 // 这句设置无效
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
完整代码:
// 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>
//js
Page({
data: {},
onReady() {
wx.createSelectorQuery().select('#testMap')
.fields({ node: true, size: true })
.exec((res) => {
let textCanvas = res[0].node;
let gl = textCanvas.getContext('webgl');
const vsSource = `
attribute vec4 aVertexPosition;
attribute vec2 aTextureCoord;
varying highp vec2 vTextureCoord;
void main(void) {
gl_Position = aVertexPosition;
vTextureCoord = aTextureCoord;
}
`;
// Fragment shader source code
const fsSource = `
varying highp vec2 vTextureCoord;
uniform sampler2D uSampler;
void main(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 buffers
const 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, new Float32Array(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, new Float32Array(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);
// 这句设置无效
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();
})
},
})