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 CAD / Development / 6894
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Subject: 
Re: BrickDraw3D development announcement
Newsgroups: 
lugnet.cad.dev
Date: 
Mon, 11 Feb 2002 19:07:59 GMT
Viewed: 
815 times
  
In lugnet.cad.dev, Travis Cobbs writes:
In lugnet.cad.dev, Erik Olson writes:
P.P.S. Does anybody know why glBegin(GL_LINES) would return
GL_INVALID_OPERATION other than because some earlier glBegin is still
outstanding?

It's easy to miss OpenGL errors.  Are you sure it's the glBegin causing the
error, and not some previous command?  Remember that successful commands
don't clear the GL error state.  Did you check for an error right before
calling glBegin?

Heh heh. Fixed this bug last night.

err = glCheckError(); // no error!
glBegin(GL_LINES);
err = glCheckError(); // dies!

In my zeal to add error checking everywhere to find the real error, I put
glCheckError inside a lot of glBegin/glEnd loops. It seems it is an "invalid
operation" to check for errors inside a loop.

Now I have been able to focus on the real bugs. The real bug was trying to
create a display list while creating another display list. (lazy evaluation
technique.) But I knew that  already and rewrote the code. Finally I can
test the code now that those spurious glCheckError are out of the way.



Message is in Reply To:
  Re: BrickDraw3D development announcement
 
(...) It's easy to miss OpenGL errors. Are you sure it's the glBegin causing the error, and not some previous command? Remember that successful commands don't clear the GL error state. Did you check for an error right before calling glBegin? (...) (23 years ago, 6-Feb-02, to lugnet.cad.dev)

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