Question

所以我迫切需要一个代码读取，如果有人会这么好 - 我不知道故障可能来自哪里 - 我一直在将这段代码与教程中的代码进行比较：

http://learningwebgl.com/lessons/lesson05/index.html

并且已经查看了大约10次 - 我只是不知道......需要专业人士的帮助...只是试图纹理一个正方形，没有任何我不关心的3D东西目前 -

    <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));

       // gl_FragColor= vec4(0.0, 1.0, 0.0, 1.0);
    }
    </script>

<script id="shader-vs" type="x-shader/x-vertex">
    attribute vec3 aVertexPosition;

    attribute vec2 aTextureCoord;

    uniform mat4 uMVMatrix;
    uniform mat4 uPMatrix;

    varying vec2 vTextureCoord;


    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.samplerUniform= gl.getUniformLocation(shaderProgram, "uSampler");



    shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
    shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
}


var mvMatrix = mat4.create();
var pMatrix = mat4.create();

function setMatrixUniforms() {
    gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
    gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}



var triangleVertexPositionBuffer;
var squareVertexPositionBuffer;

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;



    squareTexPositionBuffer=gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, squareTexPositionBuffer);

    texvert= [1.0, 0.0,
              0.0, 0.0,
              1.0, 1.0,
              0.0, 1.0];
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(texvert), gl.STATIC_DRAW);

    squareTexPositionBuffer.itemSize=2;
    squareTexPositionBuffer.numItems=4;




}


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, 0.1, 100.0, pMatrix);

    mat4.identity(mvMatrix);

    mat4.translate(mvMatrix, [-2.0, 0.0, -7.0]);


    mat4.translate(mvMatrix, [3.0, 0.0, 0.0]);

    gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
    gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

    gl.bindBuffer(gl.ARRAY_BUFFER, squareTexPositionBuffer);
    gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, squareTexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_2D, neheTexture);
    gl.uniform1i(shaderProgram.samplerUniform, 0);






    setMatrixUniforms();
    gl.drawArrays(gl.TRIANGLE_STRIP, 0, squareVertexPositionBuffer.numItems);


}


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 neheTexture;

function initTexture(){



    neheTexture = gl.createTexture();
    neheTexture.image = new Image();
    neheTexture.image.onload = function() {
        handleLoadedTexture(neheTexture)
    }

    neheTexture.image.src = "nehe.gif";

}


function webGLStart() {
    var canvas = document.getElementById("lesson01-canvas");
    initGL(canvas);
    initShaders();
    initBuffers();
    initTexture();

    gl.clearColor(0.0, 0.0, 0.0, 1.0);
    gl.enable(gl.DEPTH_TEST);

    drawScene();
}


</script>

Answer 1

不会立即加载纹理。当你有动画时，这不是问题，因为场景将在没有完全加载的情况下使用空白纹理进行渲染，一旦对象将变为纹理。在完全加载图像之前，您没有动画，只有一个绘图调用。因此，在加载图像后，您应该进行另一次绘图调用，因此使用纹理绘制场景。

类似于：

neheTexture.image.onload = function() {
    handleLoadedTexture(neheTexture);
    drawScene(); // <- now draw scene again, once I got my texture
}

希望这会有所帮助。：）

Answer 2

这是一个后续问题 - 假设我想要有两种不同的形状 - 一种带有颜色缓冲区，另一种带有纹理缓冲区，因为教程使得它几乎像你只能拥有一个或另一个，但不能同时拥有两个？

因此，在下面的代码中，我有一些纹理和一些东西使另一行代码中的颜色变成蓝色 - 我将如何在这种语言中进行区分 - 我尝试使用整数来表示两者之间的选择但它没有很好地运作......

<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));

   // gl_FragColor= vec4(0.0, 1.0, 0.0, 1.0);
}
</script>

WebGL - 用于纹理正方形，但由于某种原因它不起作用

2 个答案: