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Windows GDI question???

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Started by JIMbond21 September 03, 2003 04:27 PM

18 comments, last by JIMbond21 20 years, 7 months ago

JIMbond21

122

Author

September 03, 2003 04:27 PM

How do I eleminate the tearing effect when graphics are drawn using windows GDI? I use double buffering and my timer which makes the game run at 60 fps, and every 4 - 5 seconds it does the tearing effect. Plz Help!!!

THX,JAP

Martel

122

September 03, 2003 05:45 PM

How are you doing the double buffering? You''re just using GDI for all the rendering? Are you rendering to a window or full-screen?

JIMbond21

122

Author

September 03, 2003 07:02 PM

I use a bitmap in memory for the double buffer, then after drawing everything I blit that to the device context for the window, which I sort of make full screen by creating a maximized popup window, that appears as fullscreen. I only use GDI for rendering.

THX,JAP

LessBread

1,415

September 03, 2003 07:13 PM

The tearing could be a vertical retrace issue. Take a look at this article, perhaps it''s relevant: Detecting Vertical Retrace in Microsoft Windows.

"I thought what I'd do was, I'd pretend I was one of those deaf-mutes." - the Laughing Man

JIMbond21

122

Author

September 04, 2003 05:38 AM

Is there any easy way to detect vertical retrace when using windows GDI?

THX,JAP

noVum

170

September 04, 2003 05:46 AM

Yes, use DirectDraw

JIMbond21

122

Author

September 04, 2003 04:24 PM

Any other way without any directx?

THX,JAP

Jason Doucette

122

September 04, 2003 08:17 PM

No, there is no easy way. Detecting the retrace is low level stuff that Windows was designed to stop programs from performing. DirectX is the answer (until Longhorn arrives).

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PhilVaz

144

September 04, 2003 09:57 PM

<< Any other way without any directx? >>

I use GDI only for my full screen Asteroids game and had no tearing at all. Haven''t worked with Windows Bitmaps yet but I expect no tearing. Put a link to your source...

Are you sure you are doing this each frame: (1) erase back buffer, (2) draw all graphics to back buffer, then when all drawing done (3) BitBlt entire back to front at once. If so, you shouldn''t see any tearing...

VazGames.com

Phil P