我正在尝试在webgl中使用多个着色器程序，但仍然会遇到问题。
似乎如果我在程序中有不同数量的顶点着色器属性，那么我没有得到任何没有错误的渲染。是否有一些约束意味着程序必须具有相同数量的属性？更改程序时是否需要禁用/启用属性位置？
似乎只是创建多个程序会导致问题（我甚至不必使用第二个着色器，只是创建它会导致问题）。
创建属性我正在使用以下代码段（当所有程序中的属性数相同时，工作正常）：
for ( var i=0 ; i<vertexAttributes.length ; i++ )
{
shaderProgram[vertexAttributes[i].name] = gl.getAttribLocation(shaderProgram,vertexAttributes[i].name);
gl.enableVertexAttribArray(shaderProgram[vertexAttributes[i].name]);
}
很抱歉发布了如此大量的代码，但这最能说明问题。这是来自learningwebgl.com教程之一的代码，我所做的就是添加第二对着色器（“shader2-fs”和“shader2-vs”）和一个名为initShaders2的新函数。如果在webGLStart（）中调用initShaders2（因为它在代码中），那么什么都没有被绘制？我很困惑！
<script type="text/javascript" src="two_files/glMatrix-0.js"></script>
<script type="text/javascript" src="two_files/webgl-utils.js"></script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec4 vColor;
void main(void) {
gl_FragColor = vColor;
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec4 aVertexColor;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec4 vColor;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vColor = aVertexColor;
}
</script>
<script id="shader2-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec2 vTextureCoord;
varying vec3 vLightWeighting;
uniform sampler2D uSampler;
void main(void) {
vec4 textureColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
gl_FragColor = vec4(textureColor.rgb * vLightWeighting, textureColor.a);
}
</script>
<script id="shader2-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec3 aVertexNormal;
attribute vec2 aTextureCoord;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform mat3 uNMatrix;
uniform vec3 uAmbientColor;
uniform vec3 uLightingDirection;
uniform vec3 uDirectionalColor;
uniform bool uUseLighting;
varying vec2 vTextureCoord;
varying vec3 vLightWeighting;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vTextureCoord = aTextureCoord;
if (!uUseLighting) {
vLightWeighting = vec3(1.0, 1.0, 1.0);
} else {
vec3 transformedNormal = uNMatrix * aVertexNormal;
float directionalLightWeighting = max(dot(transformedNormal, uLightingDirection), 0.0);
vLightWeighting = uAmbientColor + uDirectionalColor * directionalLightWeighting;
}
}
</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.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor");
gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute);
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
}
var shaderProgram2;
function initShaders2() {
var fragmentShader = getShader(gl, "shader2-fs");
var vertexShader = getShader(gl, "shader2-vs");
shaderProgram2 = gl.createProgram();
gl.attachShader(shaderProgram2, vertexShader);
gl.attachShader(shaderProgram2, fragmentShader);
gl.linkProgram(shaderProgram2);
if (!gl.getProgramParameter(shaderProgram2, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
gl.useProgram(shaderProgram2);
shaderProgram2.vertexPositionAttribute = gl.getAttribLocation(shaderProgram2, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram2.vertexPositionAttribute);
shaderProgram2.vertexNormalAttribute = gl.getAttribLocation(shaderProgram2, "aVertexNormal");
gl.enableVertexAttribArray(shaderProgram2.vertexNormalAttribute);
shaderProgram2.textureCoordAttribute = gl.getAttribLocation(shaderProgram2, "aTextureCoord");
gl.enableVertexAttribArray(shaderProgram2.textureCoordAttribute);
shaderProgram2.pMatrixUniform = gl.getUniformLocation(shaderProgram2, "uPMatrix");
shaderProgram2.mvMatrixUniform = gl.getUniformLocation(shaderProgram2, "uMVMatrix");
shaderProgram2.nMatrixUniform = gl.getUniformLocation(shaderProgram2, "uNMatrix");
shaderProgram2.samplerUniform = gl.getUniformLocation(shaderProgram2, "uSampler");
shaderProgram2.useLightingUniform = gl.getUniformLocation(shaderProgram2, "uUseLighting");
shaderProgram2.ambientColorUniform = gl.getUniformLocation(shaderProgram2, "uAmbientColor");
shaderProgram2.lightingDirectionUniform = gl.getUniformLocation(shaderProgram2, "uLightingDirection");
shaderProgram2.directionalColorUniform = gl.getUniformLocation(shaderProgram2, "uDirectionalColor");
}
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 pyramidVertexPositionBuffer;
var pyramidVertexColorBuffer;
var cubeVertexPositionBuffer;
var cubeVertexColorBuffer;
var cubeVertexIndexBuffer;
function initBuffers() {
pyramidVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexPositionBuffer);
var vertices = [
// Front face
0.0, 1.0, 0.0,
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
// Right face
0.0, 1.0, 0.0,
1.0, -1.0, 1.0,
1.0, -1.0, -1.0,
// Back face
0.0, 1.0, 0.0,
1.0, -1.0, -1.0,
-1.0, -1.0, -1.0,
// Left face
0.0, 1.0, 0.0,
-1.0, -1.0, -1.0,
-1.0, -1.0, 1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
pyramidVertexPositionBuffer.itemSize = 3;
pyramidVertexPositionBuffer.numItems = 12;
pyramidVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexColorBuffer);
var colors = [
// Front face
1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
// Right face
1.0, 0.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 1.0, 0.0, 1.0,
// Back face
1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
// Left face
1.0, 0.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 1.0, 0.0, 1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
pyramidVertexColorBuffer.itemSize = 4;
pyramidVertexColorBuffer.numItems = 12;
cubeVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
vertices = [
// Front face
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, 1.0,
// Back face
-1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, 1.0, -1.0,
1.0, -1.0, -1.0,
// Top face
-1.0, 1.0, -1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
1.0, 1.0, -1.0,
// Bottom face
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
1.0, -1.0, 1.0,
-1.0, -1.0, 1.0,
// Right face
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
1.0, 1.0, 1.0,
1.0, -1.0, 1.0,
// Left face
-1.0, -1.0, -1.0,
-1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
-1.0, 1.0, -1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
cubeVertexPositionBuffer.itemSize = 3;
cubeVertexPositionBuffer.numItems = 24;
cubeVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexColorBuffer);
colors = [
[1.0, 0.0, 0.0, 1.0], // Front face
[1.0, 1.0, 0.0, 1.0], // Back face
[0.0, 1.0, 0.0, 1.0], // Top face
[1.0, 0.5, 0.5, 1.0], // Bottom face
[1.0, 0.0, 1.0, 1.0], // Right face
[0.0, 0.0, 1.0, 1.0] // Left face
];
var unpackedColors = [];
for (var i in colors) {
var color = colors[i];
for (var j=0; j < 4; j++) {
unpackedColors = unpackedColors.concat(color);
}
}
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(unpackedColors), gl.STATIC_DRAW);
cubeVertexColorBuffer.itemSize = 4;
cubeVertexColorBuffer.numItems = 24;
cubeVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
var cubeVertexIndices = [
0, 1, 2, 0, 2, 3, // Front face
4, 5, 6, 4, 6, 7, // Back face
8, 9, 10, 8, 10, 11, // Top face
12, 13, 14, 12, 14, 15, // Bottom face
16, 17, 18, 16, 18, 19, // Right face
20, 21, 22, 20, 22, 23 // Left face
];
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
cubeVertexIndexBuffer.itemSize = 1;
cubeVertexIndexBuffer.numItems = 36;
}
var rPyramid = 0;
var rCube = 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, [-1.5, 0.0, -8.0]);
mvPushMatrix();
mat4.rotate(mvMatrix, degToRad(rPyramid), [0, 1, 0]);
gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, pyramidVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, pyramidVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLES, 0, pyramidVertexPositionBuffer.numItems);
mvPopMatrix();
mat4.translate(mvMatrix, [3.0, 0.0, 0.0]);
mvPushMatrix();
mat4.rotate(mvMatrix, degToRad(rCube), [1, 1, 1]);
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, cubeVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
setMatrixUniforms();
gl.drawElements(gl.TRIANGLES, cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
mvPopMatrix();
}
var lastTime = 0;
function animate() {
var timeNow = new Date().getTime();
if (lastTime != 0) {
var elapsed = timeNow - lastTime;
rPyramid += (90 * elapsed) / 1000.0;
rCube -= (75 * elapsed) / 1000.0;
}
lastTime = timeNow;
}
function tick() {
requestAnimFrame(tick);
drawScene();
animate();
}
function webGLStart() {
var canvas = document.getElementById("lesson04-canvas");
initGL(canvas);
initShaders2(); // !!!!!!!!!!!!!!!!!!!!!!!!!
initShaders();
initBuffers();
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
tick();
}
</script>
</head>
<body onload="webGLStart();">
<a href="http://learningwebgl.com/blog/?p=370"><< Back to Lesson 4</a><br>
<canvas id="lesson04-canvas" style="border: none;" width="500" height="500"></canvas>
<br>
<a href="http://learningwebgl.com/blog/?p=370"><< Back to Lesson 4</a><br>
</body></html>
答案 0 :(得分：12)
您可能需要向我们提供更多信息，但为了让您从这里开始，请快速查看清单。每当你改变节目时，你都会想：
基本上，您希望每次更改节目时都要对待，就好像这是您第一次设置平局电话一样。