Re: Xlib problems (Lol. I've only been programming in it for 10days...)

[TI95NEUK@de.ibm.com]

Hi,

>> If you really need speed. Well, use DGA.

>I'd like to set something straight once and for all: DGA isn't that
>fast. It is "okay", but not fast. It gives you programmed I/O access to
>the framebuffer, which doesn't accelerate anything (in fact, XCopyArea
>of a largish Pixmap to a Window is WAY faster than DGA with XFree86
>3.9.x).

Sorry, I just timed our new engine:
320x240x16bpp,
XCopyArea: 62fps
DGA: 123fps

That looks like pure speed for me.
Maybe I'm the only one without a super-duper-accelerated Matrox Card,
but it sure is faster on my "cheap" S3 Virge.

btw:
If you do it right you let the user choose.
(A simple "-nodga" switches back to slower ... er ... faster pure X11)

>The page flipping is one of the biggest incentive. The video memory
>organization is useless if you can't use the hardware blitter to move
>things around (which may or may not be possible using DGA, depending on
>the version).

PageFlipping, Hardware-Scrolling and _Syncing on the Retrace_ are important for
realtime FX.

>If all you want from DGA is fullscreen access and you don't use page
>flipping, do everyone a service and use a large override_redirect Window
>at +0+0 and use xf86vmode to switch mode (or just use WidthOfScreen()
>and HeightOfScreen()).

Well, sounds good (and it's what I usually do), but when I need raw speed ...
well ...

ciao
Anti
ps:
DON'T usa DGA for your GUI. Use it only if you need realtime-animation and give
the user an option !!!