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Re: OpenGL vs. SDL for 2D

Vesselin Peev wrote:
> Steve,
> Thank you for the great information in general and the texture layout tips
> in particular! I'll research the matter deeply, though ;-))
> You said "push pixels hundreds of times faster than you can with
> the CPU alone". I wonder why you say "with the CPU alone"
> Isn't it that even a simple S3 Trio64 does 2D blitting through its own CPU
> and relieves the burden on the main CPU?

Well - yes - but it still consumes main memory bandwidth - and it's blitter
is pretty crude compared to what an OpenGL textured polygon can do for you.

Also, there isn't really a good API for driving the S3's blitter.  You can
hope that X windows will "do the right thing" - but for most cards it won't...
especially if you want some kind of a fancy blit with transparency, layering
and scale/rotate.

> So what you said still holds true l when you compare SDL on a GeForce2 and
> OpenGL/Mesa on the same GeForce2, right?

Yes - I think so.
> So why use SDL (without the OpenGL wrapping part) from now on then? It would
> die out relatively quickly if this is the situation.

SDL does much more for you than just blitting.  You have to open a window,
read the mouse/keyboard/joystick, etc.  All of those things are in prime
SDL terratory.
> Is this the reason why your PLib skips over the SDL concept, too?

PLIB is a higher layer than either SDL or OpenGL or GLUT.  You can use
PLIB *with* SDL or *with* GLUT.

----------------------------- Steve Baker -------------------------------
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