FW: XFree86 future

> On Wednesday 26 March 2003 23:24, Marco Bubke wrote:
> >/ There are texture, vertex etc. objects. It can be cached on the card so
/> >/ there is no traffic. All modern games use this way. Because of that AGP
/> >/ 8x isn't faster as AGP 4x.
/> 
> That's not strictly true. On a very basic level maybe, but if this was true 
> we'd still only have AGP 1x, and not AGP 8x.
> 
> You need to push and pull texture data through the bus in real time because 
> 64/128/256MB of texture cache isn't enough. Not to mention the fact that 
> you've only got eight lights to play with, and if you want more you have to 
> keep turning them on and off several times a scene, and similar problems. You 
> can never have enough memory, and you can never have enough bandwidth.

You can have more than 8 light, 8 are the minimum. But this is in the geomerty enigne. 
The most peoble use pixel lighting today. Look at Doom 3 for example. This have nothing
today with AGP. What do you mean by real time? The question is what do you do. For example 
a onyx is much slower in many things than consumer card but the bus is very fast. If you use 
glReadPixels it can be much faster on a SGI than on a consumer card. But the most developers try
to let the textures and geometry on the card. You need a much faster bus than AGP 8X and you 
need much faster RAM on the board too if you send the data every pass.
 
>
> >/ You can render to textures so that overlaping is nop problem.
/>
> Oh yeah, rendering to textures. That's another way to flood the AGP bus.

Why. Thats stupid. If you render to texture you render to the memory of the card. Otherwise 
you could use glReadPixels. Maybe you 
should read the Überbuffer draft and Real Time Rendering.

Marco