我正在尝试为WebGL编写一对着色器，这将允许我渲染一个颜色立方体。但是，当我尝试打开文件时，收到错误“无法初始化着色器程序”。我该如何调试这个以及在哪里开始查看着色器？我已经能够使用更具体的错误进行一些调试，但我不知道从哪种一般消息开始。非常感谢任何帮助！
这是代码：
<script id="shader-fs" type="x-shader/x-fragment">
varying lowp vec3 vColor;
varying highp vec3 vLighting;
void main(void) {
gl_FragColor = vec4(vColor * vLighting, 1.0);
}
</script>
<!-- Vertex shader program -->
<script id="shader-vs" type="x-shader/x-vertex">
attribute highp vec3 aVertexNormal;
attribute highp vec3 aVertexPosition;
attribute highp vec4 aVertexColor;
uniform highp mat4 uNormalMatrix;
uniform highp mat4 uMVMatrix;
uniform highp mat4 uPMatrix;
varying highp vec3 vLighting;
varying highp vec4 vColor;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
//Apply the coloration to the cube
vColor = aVertexColor;
// Apply lighting effect
highp vec3 ambientLight = vec3(0.6, 0.6, 0.6);
highp vec3 directionalLightColor = vec3(0.5, 0.5, 0.75);
highp vec3 directionalVector = vec3(0.85, 0.8, 0.75);
highp vec4 transformedNormal = uNormalMatrix * vec4(aVertexNormal, 1.0);
highp float directional = max(dot(transformedNormal.xyz, directionalVector), 0.0);
vLighting = ambientLight + (directionalLightColor * directional);
}
</script>
以下是编译着色器的代码：
//
// initShaders
//
// Initialize the shaders, so WebGL knows how to light our scene.
//
function initShaders() {
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
// Create the shader program
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
// If creating the shader program failed, alert
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Unable to initialize the shader program.");
}
gl.useProgram(shaderProgram);
vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(vertexPositionAttribute);
vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor");
gl.enableVertexAttribArray(vertexColorAttribute);
vertexNormalAttribute = gl.getAttribLocation(shaderProgram, "aVertexNormal");
gl.enableVertexAttribArray(vertexNormalAttribute);
}
//
// getShader
//
// Loads a shader program by scouring the current document,
// looking for a script with the specified ID.
//
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
// Didn't find an element with the specified ID; abort.
if (!shaderScript) {
return null;
}
// Walk through the source element's children, building the
// shader source string.
var theSource = "";
var currentChild = shaderScript.firstChild;
while(currentChild) {
if (currentChild.nodeType == 3) {
theSource += currentChild.textContent;
}
currentChild = currentChild.nextSibling;
}
// Now figure out what type of shader script we have,
// based on its MIME type.
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; // Unknown shader type
}
// Send the source to the shader object
gl.shaderSource(shader, theSource);
// Compile the shader program
gl.compileShader(shader);
// See if it compiled successfully
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert("An error occurred compiling the shaders: " + gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
----------------------- EDIT ----------------------- ---------- 我根据下面的建议进行了更改，现在打开文件时屏幕完全空白。以前，显示黑色画布，但现在屏幕是白色的。我很感激你能给出的任何建议。谢谢！
<script id="shader-fs" type="x-shader/x-fragment">
varying lowp vec4 vColor;
varying mediump vec3 vLighting;
void main(void) {
gl_FragColor = vColor * vec4(vLighting, 1.0);
}
</script>
<!-- Vertex shader program -->
<script id="shader-vs" type="x-shader/x-vertex">
attribute mediump vec3 aVertexNormal;
attribute mediump vec3 aVertexPosition;
attribute mediump vec4 aVertexColor;
uniform mediump mat4 uNormalMatrix;
uniform mediump mat4 uMVMatrix;
uniform mediump mat4 uPMatrix;
varying mediump vec3 vLighting;
varying mediump vec4 vColor;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
//Apply the coloration to the cube
vColor = aVertexColor;
// Apply lighting effect
mediump vec3 ambientLight = vec3(0.6, 0.6, 0.6);
mediump vec3 directionalLightColor = vec3(0.5, 0.5, 0.75);
mediump vec3 directionalVector = vec3(0.85, 0.8, 0.75);
mediump vec4 transformedNormal = uNormalMatrix * vec4(aVertexNormal, 1.0);
mediump float directional = max(dot(transformedNormal.xyz, directionalVector), 0.0);
vLighting = ambientLight + (directionalLightColor * directional);
}
</script>
答案 0 :(得分：5)
也许你应该更新你的框架，所以当它收到错误编译它会查询WebGL的错误并打印它？编辑着色器后，如果未成功，请在
中调用gl.getShaderInfoLog
// Compile the shader
gl.compileShader(shader);
// Check the compile status
var compiled = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
if (!compiled) {
// Something went wrong during compilation; get the error
console.error(gl.getShaderInfoLog(shader));
在
中进行链接时，您应该执行类似的操作gl.linkProgram(program);
// Check the link status
var linked = gl.getProgramParameter(program, gl.LINK_STATUS);
if (!linked) {
// something went wrong with the link
console.error(gl.getProgramInfoLog(program));
当我用我的框架尝试它时，我从WebGL
得到了这个错误
var canvas = document.getElementById("c");
var gl = canvas.getContext("webgl");
var program = twgl.createProgramFromScripts(
gl, ["shader-vs", "shader-fs"], ["a_position"]);<script id="shader-fs" type="x-shader/x-fragment">
varying lowp vec3 vColor;
varying highp vec3 vLighting;
void main(void) {
gl_FragColor = vec4(vColor * vLighting, 1.0);
}
</script>
<!-- Vertex shader program -->
<script id="shader-vs" type="x-shader/x-vertex">
attribute highp vec3 aVertexNormal;
attribute highp vec3 aVertexPosition;
attribute highp vec4 aVertexColor;
uniform highp mat4 uNormalMatrix;
uniform highp mat4 uMVMatrix;
uniform highp mat4 uPMatrix;
varying highp vec3 vLighting;
varying highp vec4 vColor;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
//Apply the coloration to the cube
vColor = aVertexColor;
// Apply lighting effect
highp vec3 ambientLight = vec3(0.6, 0.6, 0.6);
highp vec3 directionalLightColor = vec3(0.5, 0.5, 0.75);
highp vec3 directionalVector = vec3(0.85, 0.8, 0.75);
highp vec4 transformedNormal = uNormalMatrix * vec4(aVertexNormal, 1.0);
highp float directional = max(dot(transformedNormal.xyz, directionalVector), 0.0);
vLighting = ambientLight + (directionalLightColor * directional);
}
</script>
<script src="https://twgljs.org/dist/3.x/twgl.min.js"></script>
<canvas id="c"></canvas>
Error in program linking:Varyings with the same name but different type,
or statically used varyings in fragment shader are not declared in
vertex shader: vColor
这似乎指出了错误。