尝试 glUseProgram 时出现 Opengl 错误 1281

我有什么想法可以调试这个opengl进一步错误？1281

我正在从文件加载源代码，编译，链接，然后尝试检查错误glUseProgram

在我的对象的绘制方法中..

log.info(gl2.glIsProgram(shaderProgram)); // true
gl2.glUseProgram(shaderProgram);

int error;
while ((error = gl2.glGetError()) != GL2.GL_NO_ERROR) {
    throw new RuntimeException("glUseProgram" + ": glError " + error);
}

输出 ..

[13:38:08] INFO (IARectangle.java:99) - true
java.lang.RuntimeException: glUseProgram: glError 1281

这就是我从 .glsl 文件加载着色器源的方式..

Vector<Integer> shaders = new Vector<Integer>();

try {

    shaders.add(compileSource(
        loadSource("shaders/vertexShader.glsl"),
        loadSource("shaders/fragmentShader.glsl")));

    return shaders;

} catch (Exception e) {
    e.printStackTrace();
    return shaders;
}

public String[] loadSource(String filename){

    StringBuilder sb = new StringBuilder();
    try {

        InputStream is = getClass().getClassLoader().getResourceAsStream(filename);
        BufferedReader br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
        String line;
        while ((line = br.readLine()) != null) {

            sb.append(line);
            sb.append('\n');
        }
        is.close();

    } catch (Exception e) {
        e.printStackTrace();
    }

    return new String[] { sb.toString() };
}

public final int compileSource(final String[] vertexSource, final String[] fragmentSource) throws Exception {

     vertexShaderProgram;
    int fragmentShaderProgram;
    int shaderProgram;

    // load vertexShader source, compile and verify
    vertexShaderProgram = gl2.glCreateShader(GL2.GL_VERTEX_SHADER);
    gl2.glShaderSource(vertexShaderProgram, 1, vertexSource, null, 0);
    gl2.glCompileShader(vertexShaderProgram);
    verifyCompile(gl2, vertexShaderProgram);

    // load fragmentShader source, compile and verify
    fragmentShaderProgram = gl2.glCreateShader(GL2.GL_FRAGMENT_SHADER);
    gl2.glShaderSource(fragmentShaderProgram, 1, fragmentSource, null, 0);
    gl2.glCompileShader(fragmentShaderProgram);
    verifyCompile(gl2, fragmentShaderProgram);

    shaderProgram = gl2.glCreateProgram();

    gl2.glAttachShader(shaderProgram, vertexShaderProgram);
    gl2.glAttachShader(shaderProgram, fragmentShaderProgram);
    gl2.glLinkProgram(shaderProgram);
    IntBuffer intBuffer = IntBuffer.allocate(1);
    gl2.glGetProgramiv(shaderProgram, GL2.GL_LINK_STATUS, intBuffer);

    if (intBuffer.get(0) != 1){

        String infoLog = null;
        gl2.glGetProgramiv(shaderProgram, GL2.GL_INFO_LOG_LENGTH, intBuffer);
        int size = intBuffer.get(0);
        log.error("Program link error: ");
        if (size > 0) {

            ByteBuffer byteBuffer = ByteBuffer.allocate(size);
            gl2.getGL2().glGetProgramInfoLog(shaderProgram, size, intBuffer, byteBuffer);
            byte[] sizeBytes = new byte[size];
            byteBuffer.get(sizeBytes, 0, size);
            infoLog = new String(sizeBytes);

            log.error("info: " + infoLog);

        } else {
            log.error("Unknown");
        }
        System.exit(1);
        return shaderProgram;

    } else {

        return shaderProgram;
    }
}

顶点着色器源码..

#version 120

uniform mat4 uMVPMatrix;
attribute vec4 vPosition;

void main() {
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
    //gl_Position = uMVPMatrix * vPosition;
}

片段着色器源码..

#version 120

uniform vec4 vColor;

void main() {
    gl_FragColor = vColor;
}

乍一看，我不知道为什么glGetError正在返回错误代码。但为了回答您的具体问题“如何进一步调试此错误？”，我确实有一个建议。

将您的绘制代码更改为：

// Logging errors before the call to glUseProgram
int error;
while ((error = gl2.glGetError()) != GL2.GL_NO_ERROR) {
    log.info(error);
}

log.info(gl2.glIsProgram(shaderProgram)); // true
gl2.glUseProgram(shaderProgram);

int error;
while ((error = gl2.glGetError()) != GL2.GL_NO_ERROR) {
    throw new RuntimeException("glUseProgram" + ": glError " + error);
}

请注意，这里的区别是我们添加了一个代码块来记录返回的错误glGetError before打电话给glUseProgram。原因是因为该错误不一定源自您的调用glUseProgram。如果您看到使用上面的代码记录的 1281 错误，您可以确定该错误实际上是源自在glUseProgram call.

看看文档 https://www.opengl.org/sdk/docs/man/docbook4/xhtml/glGetError.xml for glGetError:

glGetError 返回错误标志的值。每个可检测到的错误 被分配了数字代码和符号名称。当发生错误时， 错误标志被设置为适当的错误代码值。没有其他 错误会被记录，直到调用 glGetError 为止，错误代码为 返回，并且标志重置为 GL_NO_ERROR。

因此，如果您早期的 OpenGL 调用之一（可能是您的compileSource函数，例如）记录了1281错误，并且您没有调用glGetError从该点到您的呼叫之间的任何位置glUseProgram，您不能合理地假设该错误实际上源自glUseProgram call.

总之，glGetError不返回 OpenGL 调用记录的最新错误。你需要打电话glGetError具有更大的粒度，以便查明错误的根源。这将使您能够解决所遇到的问题并准确确定哪个 OpenGL 调用正在记录错误。