Bug 23417

Summary:	FBO / Windows software rendering: flickering due to errornous blit
Product:	Mesa	Reporter:	Florian Kirsch <florian.kirsch>
Component:	Drivers/DRI/swrast	Assignee:	mesa-dev
Status:	RESOLVED MOVED	QA Contact:
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	All
OS:	Windows (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	Example program demonstrating the flickering

Description Florian Kirsch 2009-08-19 13:56:02 UTC

Created attachment 28793 [details]
Example program demonstrating the flickering

I have found a bug in the frame buffer object implementation, happening with Mesa 7.4.4 using Mesa with software rendering and Windows XP.

The problem is that most of the FBO functions, such as glBindFramebufferEXT(), in their implementation fbobject.c call ctx->Driver.Flush(ctx), which then causes wmesa_flush() in wmesa.c to do a BitBlt into the visible viewer window (when double buffering is on). This clears the window ahead of time, causing severe flickering.

The simple, attached example program - a hacked gears.c with additional glBindFramebufferEXT(...) in the draw() function - should demonstrate the flickering.

For me, it helps to just comment out all lines with ctx->Driver.Flush(ctx) in fbobject.c. FBOs then work fine in the Windows software rasterizer. For other rendering paths, I guess this is not a good fix, of course.

Comment 1 Marek Olšák 2011-03-01 17:06:01 UTC

Is this an issue with latest Mesa?

Comment 2 GitLab Migration User 2019-09-18 18:44:07 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/292.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.