Re: [linuxgames] Poll: Video Access

[Steve Baker <sjbaker1@airmail.net>]

Jan Ekholm wrote:

> Speaking of which, I have a small image viewer I made in SDL for use on
> our set-top box connected to the TV. It uses raw SDL and SDL_image to load
> and show images and works very well. Would it benefit from loading the
> images into textures and using OpenGL for the display? Raw speed would
> probably not be improved at all, but it could facilitate all kinds of nice
> effects when switching between images: fades, rotates, zooms etc, stuff
> that the normal "pixel based" images can't really achieve.
Overall, your AGP bus bandwidth is likely to be the limiting factor.
Switching to downloading and rendering a texture doesn't help that at
all - so I'd be suprised if you got much of a speedup.

However, as you say, you gain a spectacular ability to zoom, shrink,
rotate, mirror, fade, false-colour, do brightness and contrast changes,
switch to monochrome, add motion blur, wrap the image around a teapot...all
pretty much for free.

However, for a sprite-based 2D game, most of the sprites don't need to be
re-downloaded into the hardware every frame.  In that case, you can go
from sending many millions of bytes down the AGP bus to sending a few
thousand bytes of vertex data.  Then, add the fact that you get sprite
occlusion, rotation, scaling, antialiasing, and transparency all for
free - and this is definitely the way to go - unless you are writing
a game for people with graphics cards that date back to the upper
mesozoic era.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net>    WorkEmail: <sjbaker@link.com>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
           http://tuxkart.sf.net http://prettypoly.sf.net
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