Why does the shader program fail to compile despite linking and validating successfully?

Question

Shader program does not link despite the vertex and fragment shaders compiling successfuly. No error message is retreived using glGetProgramInfoLog(). A value of GL_FALSE is, however, retreived within the success buffer variable (the GLException is thrown with an empty message). Here is the code:

private int compileProgram(String[] vertexShaderSource, String[] fragmentShaderSource) 
        throws GLException {
    // compiling vertex and fragment shaders from source

    int vertexShader = compileShader(GL4.GL_VERTEX_SHADER, vertexShaderSource); // OK
    int fragmentShader = compileShader(GL4.GL_FRAGMENT_SHADER, fragmentShaderSource); // OK
    int id = gl.glCreateProgram(); // OK

    // attaching the shaders to the shader program and linking it

    gl.glAttachShader(id, vertexShader);
    gl.glAttachShader(id, fragmentShader);
    gl.glLinkProgram(id);
    gl.glDeleteShader(vertexShader);
    gl.glDeleteShader(fragmentShader);

    IntBuffer success = IntBuffer.allocate(1);

    gl.glGetProgramiv(id, GL4.GL_COMPILE_STATUS, success);    // GL_FALSE

    // checking for errors

    if (success.get(0) == GL4.GL_FALSE) {
        IntBuffer infoLogLength = IntBuffer.allocate(1);

        gl.glGetProgramiv(id, GL4.GL_INFO_LOG_LENGTH, infoLogLength);

        ByteBuffer infoLog = ByteBuffer.allocate(infoLogLength.get(0));

        gl.glGetProgramInfoLog(id, infoLogLength.get(0), infoLogLength, infoLog);

        // Empty error message           

        String errorMessage = new String(infoLog.array(), Charset.forName("UTF-8"));

        throw new GLException(errorMessage);
    }

     return id;
}

Here is a link to the file containing the two shaders (in the program, each shader is actually contained within its own String[] variable).

P.S.: I have the same code structure in C++ and it works flawlessly.

Answer 1

gl.glGetProgramiv(id, GL4.GL_COMPILE_STATUS, success);    // GL_FALSE

Program object do not have a compile status, only shaders do. Trying to query GL_COMPILE_STATUS on a program object will only result in a GL_INVALID_ENUM value, and the content of your success value will not be modified in any way.