# fullscreen bug on radeon cards

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Hi, I experienced a bug on radeon games on my last openGL project, It appears that in fullscreen mode (only) the games doesnt display correctly , you show lines moving fast on the whole screen , but after the splash screen ( which dispays correctly and is in openGL too) It seems that the problem is related to VSync because when I set wait for VSync in the openGL dispay settings , the game dispays better ( no more lines but a little flickering ...) If I take a screeshot of my screen , It actually displays correctly in Paint , so the problem is directly related to display and dispay only (no openGL error code, no others bugs in the game ...) I ve tried to comment some pieces of code to show which part of code causes the problem but I can find it . So have you ever experienced problem like this and how to fix it Thanx in advance

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That sounds like 'tearing'? Caused by not having vsync on.

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the game displays correctly on ati rage , geforce 2 and 4 , intel cards ,

and also the splash screen dispays correctly and it is openGL too , so it s very strange..

and the problem is specific to this project , on others projects that I have made dispays is fine even if vsync is off

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Quote:
 Original post by venomelektrothe game displays correctly on ati rage , geforce 2 and 4 , intel cards ,and also the splash screen dispays correctly and it is openGL too , so it s very strange..and the problem is specific to this project , on others projects that I have made dispays is fine even if vsync is off

The appearance of tearing depends on the frame rate, and the how much difference there is between the frames. If your splash screen looks the same every frame, you'd never notice.

However, if the outputed image between frames is different, you will see some of the new frame and some of the previous frame at the same time, and it will appear to have a line down the screen. The bigger the difference, the more noticeable it will be.

I don't know the proper way to explain this, but you have a portion of your vram that holds the screen, and the monitor draws that to the screen x times a second. When you flip your backbuffer, the monitor is still updating the screen. So it's possible to see parts of the new frame and parts of the old.

-edit

btw, nice screenshots on your page.

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my splash is not constant , as i draw a progress bar on it

Progress(0.1f,&Win);// ... etc ...

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Look through a running ventilator in front of a usual TV screen (not LCD). You'll also see lines. That effect is very similar. It's normal. On the splash screen, you probably don't see the effect since the part of the screen that is actually changing is very small.

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No, it s not normal at all

I ve made a lot of openGL programs and it is the first time I experienced it..

The fact is that you can't play the game because the display is so crappy , no only a few lines and some flickering ...

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Quote:
 Original post by venomelektroNo, it s not normal at all

Correct. We are just bullshitting you. The real problem is a demon in your video card! ESCAPE WHILE YOU CAN!

Why don't you post your screen drawing code at least?

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lol

finally fix the problem

I have made some change in the code and put swap buffers in another function and forgot to remove it from the old place

so It was called two times by frame and causes this big issue