WebGL中L形tetris块上的纹理

Question

我试着了解WebGL中的纹理。我想在webgl tetris中的块上实现纹理。我使用这里的代码：http://learningwebgl.com/blog/?p=507来学习纹理。我的问题是如何在这种L形或不同的方形形状上实现纹理。很明显，我编写的这段代码（只是对教程的一些小改动 - 在initBuffers方法中使它成为2d）不起作用，我也没有任何线索。

<script type="text/javascript" src="glMatrix-0.9.5.min.js"></script>
<script type="text/javascript" src="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 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 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 neheTexture;
    function initTexture() {
        neheTexture = gl.createTexture();
        neheTexture.image = new Image();
        neheTexture.image.onload = function () {
            handleLoadedTexture(neheTexture)
        };
        neheTexture.image.src = 'nehe.gif';
    }
    var mvMatrix = mat4.create();
    var mvMatrixStack = [];
    var pMatrix = mat4.create();
    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 cubeVertexPositionBuffer;
    var cubeVertexTextureCoordBuffer;
    var cubeVertexIndexBuffer;
    function initBuffers() {
        cubeVertexPositionBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
        var vertices = [
            -0.5, -1.5, 0.0,
            0.5, -1.5, 0.0,
            -0.5, 1.5, 0.0,
            0.5, 1.5, 0.0,
            0.5, -0.5, 0.0,
            1.5, -0.5, 0.0,
            1.5, -1.5, 0.0
        ];
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
        cubeVertexPositionBuffer.itemSize = 3;
        cubeVertexPositionBuffer.numItems = 7;
        cubeVertexTextureCoordBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
        var textureCoords = [
            // Front face
            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);
        cubeVertexTextureCoordBuffer.itemSize = 2;
        cubeVertexTextureCoordBuffer.numItems = 4;
        cubeVertexIndexBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
        var cubeVertexIndices = [
            0,1,2,  1,2,3,
                4,5,6, 6,1,4
        ];
        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
        cubeVertexIndexBuffer.itemSize = 1;
        cubeVertexIndexBuffer.numItems = 12;
    }
    var xRot = 0;
    var yRot = 0;
    var zRot = 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, 0.1, 100.0, pMatrix);
        mat4.identity(mvMatrix);
        mat4.translate(mvMatrix, [0.0, 0.0, -25.0]);
        //mat4.rotate(mvMatrix, degToRad(xRot), [1, 0, 0]);
        //mat4.rotate(mvMatrix, degToRad(yRot), [0, 1, 0]);
        //mat4.rotate(mvMatrix, degToRad(zRot), [0, 0, 1]);
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
        gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
        gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, cubeVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, neheTexture);
        gl.uniform1i(shaderProgram.samplerUniform, 0);
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
        setMatrixUniforms();
        gl.drawElements(gl.TRIANGLES, cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
    }
    var lastTime = 0;
    function animate() {
        var timeNow = new Date().getTime();
        if (lastTime != 0) {
            var elapsed = timeNow - lastTime;
            xRot += (90 * elapsed) / 1000.0;
            yRot += (90 * elapsed) / 1000.0;
            zRot += (90 * elapsed) / 1000.0;
        }
        lastTime = timeNow;
    }
    function tick() {
        requestAnimFrame(tick);
        drawScene();
        animate();
    }
    function webGLStart() {
        var canvas = document.getElementById("lesson05-canvas");
        initGL(canvas);
        initShaders();
        initBuffers();
        initTexture();
        gl.clearColor(0.0, 0.0, 0.0, 1.0);
        gl.enable(gl.DEPTH_TEST);
        tick();
    }
</script>

Answer 1

通常，您需要相同数量的纹理坐标到位置。在您的代码中，您有7个位置，但只有4个纹理坐标