little problems with weird lines

OpenGL OpenGL: Basic Coding
1

hello,

I am creating a game with OpenGL which seems to work fine on my computer and my laptop, but apparently somebody tested it and he had lines over each polygons…

Here is a screenshot of his screen (weird lines) :
Screenshot with bug

Here are screenshots taken by me (no lines) :
Screenshots taken by me

Does anybody knows why he can see these lines ?

His graphic card is a GeForce 7600 GT/PCI/SSE2/3DNOW!
And my graphic cards are GeForce 7600 GS (pc) and Radeon X1600 (laptop).

Thanks.

2

Those look like polygon smoothing artefacts.
But then you would have those as well on your 7600. :confused:
Are you running with antialiasing enabled and he doesn’t? That would explain why you don’t have the problem if that’s it.

Check if you have glEnable(GL_POLYGON_SMOOTH) anywhere in your code and remove all occurances of it.

3

Hello,

I didn’t have any occurances of “GL_POLYGON_SMOOTH” in all my source code…

Maybe I should add it ?

Thanks

4

Don’t!

If you use any third party libraries, make sure they don’t do it either.

Out of curiosity you could check if you can repro the corruption on your GeForce by adding glEnable(GL_POLYGON_SMOOTH), but do not ship that.

You could also explicitly call glDisable(GL_POLYGON_SMOOTH) and see if that fixes the problem on the other system.

There might be other ways to generate these images, but the wrong one just looks too much like polygon smoothing with depth buffering enabled.
Means if it’s not this, you’d need to provide the rendering code.

5

Hello,

Hum… i’ve added it but it doesn’t change anything on my computer :-/.

I’m just using OpenGl, OpenGlut and Glu.

I’ll try to add glDisable(GL_POLYGON_SMOOTH) and see if anybody else got a problem.

Thanks a lot.

6

Hum… i’ve added it but it doesn’t change anything on my computer :-/.
That was on the GF7600? I would expect that GL_POLYGON_SMOOTH would have an effect on that. It’s a rather new board.
There were some implementations which just ignored polygon smoothing.

Just another idea, if there is no OpenGL ICD installed you would pick the Microsoft SW OpenGL implementation. For debugging try to select one of those pixelformats, that are the ones where the PIXELFORMATDESCRIPTOR dwFlags has PFD_GENERIC_FORMAT set.
Check if that reacts differently on the polygon smoothing.
If your program has an option to report the strings from glGetString GL_VENDOR, GL_VERSION and GL_RENDERER let your users report these when they see problems.