CompileGLShader

//-----------------------------------------------------------------------------
// Purpose: Compiles a GL shader program and returns the handle. Returns 0 if
//            the shader couldn't be compiled for some reason.
//-----------------------------------------------------------------------------
GLuint CMainApplication::CompileGLShader( const char *pchShaderName, const char *pchVertexShader, const char *pchFragmentShader )
{
    GLuint unProgramID = glCreateProgram();

    GLuint nSceneVertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource( nSceneVertexShader, 1, &pchVertexShader, NULL);
    glCompileShader( nSceneVertexShader );

    GLint vShaderCompiled = GL_FALSE;
    glGetShaderiv( nSceneVertexShader, GL_COMPILE_STATUS, &vShaderCompiled);
    if ( vShaderCompiled != GL_TRUE)
    {
        dprintf("%s - Unable to compile vertex shader %d! ", pchShaderName, nSceneVertexShader);
        glDeleteProgram( unProgramID );
        glDeleteShader( nSceneVertexShader );
        return 0;
    }
    glAttachShader( unProgramID, nSceneVertexShader);
    glDeleteShader( nSceneVertexShader ); // the program hangs onto this once it's attached

    GLuint  nSceneFragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource( nSceneFragmentShader, 1, &pchFragmentShader, NULL);
    glCompileShader( nSceneFragmentShader );

    GLint fShaderCompiled = GL_FALSE;
    glGetShaderiv( nSceneFragmentShader, GL_COMPILE_STATUS, &fShaderCompiled);
    if (fShaderCompiled != GL_TRUE)
    {
        dprintf("%s - Unable to compile fragment shader %d! ", pchShaderName, nSceneFragmentShader );
        glDeleteProgram( unProgramID );
        glDeleteShader( nSceneFragmentShader );
        return 0;    
    }

    glAttachShader( unProgramID, nSceneFragmentShader );
    glDeleteShader( nSceneFragmentShader ); // the program hangs onto this once it's attached

    glLinkProgram( unProgramID );

    GLint programSuccess = GL_TRUE;
    glGetProgramiv( unProgramID, GL_LINK_STATUS, &programSuccess);
    if ( programSuccess != GL_TRUE )
    {
        dprintf("%s - Error linking program %d! ", pchShaderName, unProgramID);
        glDeleteProgram( unProgramID );
        return 0;
    }

    glUseProgram( unProgramID );
    glUseProgram( 0 );

    return unProgramID;
}