我已经学会了如何在WebGL中添加一些对象，旋转它们。
但我在纹理化过程中遇到了问题。
<html>
<head>
<title>3D Plane Map</title>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<style type="text/css">
html, body, #canvas-main {
width: 100%;
height: 100%;
min-height: 500px;
min-width: 900px;
margin: 0px;
}
</style>
<script type="text/javascript" src="scripts/glMatrix.js"></script>
<script type="text/javascript" src="scripts/webgl-utils.js"></script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
void main(void) {
gl_FragColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec2 aTextureCoord;
varying vec2 vTextureCoord;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vTextureCoord = aTextureCoord;
}
</script>
<script type="text/javascript">
var gl;
function initGL(canvas) {
try {
gl = canvas.getContext("experimental-webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
} catch (e) {
}
if (!gl) {
alert("Could not initialise WebGL, sorry :-(");
}
}
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
var str = "";
var k = shaderScript.firstChild;
while (k) {
if (k.nodeType == 3) {
str += k.textContent;
}
k = k.nextSibling;
}
var shader;
if (shaderScript.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (shaderScript.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 fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
}
function handleLoadedTexture(texture) {
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
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.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.bindTexture(gl.TEXTURE_2D, null);
}
var myTexture;
function initTexture() {
myTexture = gl.createTexture();
myTexture.image = new Image();
myTexture.image.onload = function () {
handleLoadedTexture(myTexture)
}
myTexture.image.src = "moscow.jpg";
}
var mvMatrix = mat4.create();
var pMatrix = mat4.create();
var mvMatrixStack = [];
function mvPushMatrix() {
var copy = mat4.create();
mat4.set(mvMatrix, copy);
mvMatrixStack.push(copy);
}
function mvPopMatrix() {
if (mvMatrixStack.length == 0) {
throw "Invalid popMatrix!";
}
mvMatrix = mvMatrixStack.pop();
}
function setMatrixUniforms() {
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}
function degToRad(degrees) {
return degrees * Math.PI / 180;
}
var squareVertexPositionBuffer;
var squareVertexTextureCoordBuffer;
var squareVertexIndexBuffer;
function initBuffers() {
squareVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
vertices = [
1.0, 1.0, 0.0,
-1.0, 1.0, 0.0,
1.0, -1.0, 0.0,
-1.0, -1.0, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
squareVertexPositionBuffer.itemSize = 3;
squareVertexPositionBuffer.numItems = 4;
squareVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexTextureCoordBuffer);
var textureCoords = [
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
squareVertexTextureCoordBuffer.itemSize = 2;
squareVertexTextureCoordBuffer.numItems = 4;
}
var rSquare = 0;
function drawScene() {
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
mat4.perspective(45, gl.viewportWidth / gl.viewportHeight / 3, 0.1, 100.0, pMatrix);
mat4.identity(mvMatrix);
mat4.translate(mvMatrix, [0.0, 0.0, -5.0]);
mvPushMatrix();
mat4.rotate(mvMatrix, degToRad(rSquare), [1, 0, 0]);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, squareVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, myTexture);
gl.uniform1i(shaderProgram.samplerUniform, 0);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLE_STRIP, 0, squareVertexPositionBuffer.numItems);
mvPopMatrix();
}
var lastTime = 0;
function animate() {
var timeNow = new Date().getTime();
if (lastTime != 0) {
var elapsed = timeNow - lastTime;
rSquare += (75 * elapsed) / 1000.0;
}
lastTime = timeNow;
}
function tick() {
requestAnimFrame(tick);
drawScene();
animate();
}
function webGLStart() {
var canvas = document.getElementById("canvas-main");
initGL(canvas);
initShaders();
initBuffers();
initTexture();
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
drawScene();
tick();
}
</script>
</head>
<body onload="webGLStart();">
<canvas id="canvas-main" style="border: none; width: 100%; height: 100%;"></canvas>
</body>
</html>
当我启动Chrome调试器时，它给了我这样一个错误：
PS我试图在网上搜索一些信息，但我的问题没有太多信息，只有很少的链接。
[.WebGLRenderingContext]RENDER WARNING: texture bound to texture unit 0 is not renderable. It maybe non-power-of-2 and have incompatible texture filtering or is not 'texture complete' 192.168.1.179/plane/:1
50
WebGL: drawArrays: texture bound to texture unit 0 is not renderable. It maybe non-power-of-2 and have incompatible texture filtering or is not 'texture complete'. Or the texture is Float or Half Float type with linear filtering while OES_float_linear or OES_half_float_linear extension is not enabled. 192.168.1.179/plane/:1
202
WebGL: drawArrays: texture bound to texture unit 0 is not renderable. It maybe non-power-of-2 and have incompatible texture filtering or is not 'texture complete'. Or the texture is Float or Half Float type with linear filtering while OES_float_linear or OES_half_float_linear extension is not enabled. 192.168.1.179/plane/:244
WebGL: too many errors, no more errors will be reported to the console for this context. 192.168.1.179/plane/:244
答案 0 :(得分：4)
答案很清楚，就像水晶一样。对不起我的注意力不集中。
问题是，因为对于mipmapping，纹理必须是power-of-2的整数类型。
我的纹理是400x300，这就是为什么会发生这样的错误，当我改为512x512时，错误已经解决了。
如果你想检查你的整数是2的幂，那么使用这样简单的公式：
A & (A-1) == 0
答案 1 :(得分：0)
实际上，检查本身是不够的，它对零（0）无效。
相反，请考虑bool isPowerOfTwo = A && !( A & ( A - 1 ));
来源：https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2