catching OpenGL errors...

[dletozeun]

Hello,

I am trying to catch OpenGL errors.
So, I wrote a class that do this job:

class OGLlog : public Log
{
    public:
        OGLlog(char* fn);
 
        /**
         * @brief returns 1 if an OpenGL error occurred, 0 otherwise
         */
        static int printError(char* fn)
		{
    		GLenum glErr;
    		int retCode = 0;
 
    		glErr = glGetError();
 
			ofstream f(fn, ios::app);
			if(f.is_open())
			{
			    tm now;
  				time_t t;
 
  				time(&t);
  				now=*localtime(&t);
 
    			while (glErr != GL_NO_ERROR)
    			{
        			f<<now.tm_hour<<":"<<now.tm_min<<":"<<now.tm_sec<<"  /!\\ GL ERROR: "<<gluErrorString(glErr)<<endl;
        			retCode = 1;
        			glErr = glGetError();
       			}
      		} 			
   			else return -1;	
 
   			f.close();
 
    		return retCode;
		}
};

And now, this is the problem: When I call the printError function, My program stays stuck in the while loop that check if an ogl error remains!
I always have the opengl invalid operation error.

The more strange is that error occurs, even in the beginning of my program, where I did not call any opengl function!

I think that a fresh eye will see the big mistake I have made!

Thanks a lot.

[Bob]

If you by "at the beginning of the program" means before you set up the rendereing context, then that's perfectly normal behaviour. You cannot call any OpenGL functions before a rendering context is propely configured. If you call glGetError before the rendering context is configured, it will return GL_INVALID_OPERATION if I remember correct, becuse it's an invalid operation to call it without a rendering context.

[Ido Ilan]

Hi,

As Bob said just check if an RC is current:
if (wglGetCurrentContex() != null) ....

Ido

[sqrt[-1]]

FYI: If you are trying to find OpenGL errors, this can be done automatically via tools like:

http://www.opengl.org/sdk/tools/GLIntercept/

http://www.opengl.org/sdk/tools/gDEBugger/

[dletozeun]

Ok thank you guys, I understand know. It is just like you said, I did not define the rendering context I did know it is mandatory...

thank you sqrt[-1], for these links, it may be useful.