Jaguar
Well seeing that all the VRam will be used into a fully accelearted Open GL scene, won't you need like an awesome awesome vid card for that? Won't dvd playback and quicktime movies be laggy? Not to mention on those iBooks, are they equipped to even handle a dvd movie while surfing the net? What do you think?
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QE will only work on systems with a Geforce 2MX, Radeon, or better. Systems with older video cards will run Quartz in software like all systems do now in 10.1. QE and Quartz also look identical, so rich Mac users will only get snappier performance and not snappier visuals.
QE can also be disabled if you're having problems with it. The only situation I can think of where you'd need to do this is if you were driving a resolution to high for your VRAM to handle.
That said, 16MB of VRAM on a TiBook/iBook should be fine as long as you don't hook up to an external display. If you have 32MB of VRAM if don't think you have anything to worry about.
[ 06-26-2002: Message edited by: Keeksy ]</p>
The only issue with VRAM and QE is how many windows you have, and how big they are. 16 MB is 4194304 32-bit pixels. Of course some of that video memory is going to be used to store triangle data for the windows and such...
Anyway, if all your windows together plus the triangle data for the windows fit in that 16MB space you'll get your fastest results. Since the card is able to draw hundreds of thousands of triangles per second, drawing a few windows won't take any time at all, and you'll easily be getting a frame rate in the hundreds during drag and scroll operations. During genie operations, the window is broken down into thousand of ttriangles, so I can't be sure how fast those might be, but the Mobility Radeon should be plenty for that to remain far above the refreseh rate.
Once your windows total more than 400000 or so pixels, you're going to start storing some of the texturing for the windows in system memory and accessing it across the AGP bus, then compositing it. The bus is quite fast, and you'll still go faster than normal Quartz, but it will be a definite hit compared to sticking within the VRAM. A lot depends on the efficiency of the driver here. ATi drivers are good at this, and nVidia's drivers are and have always been notoriously bad at it. If you have a Radeon and many windows open, you're going to do better than those with an nVidia card and the same amount of VRAM.
Now, Apple has done testing on normal working conditions, and on the basis of that it recommends 32 MB of VRAM, but only requires a Radeon or nVidia 2X AGP card. This means normal use tends to come in under 32MB and over 16MB.
So, if you have 16MB of RAM, are you stuck with slow performance? Not at all. The windows are only stored in VRAM if their application isn't hidden or minimized. Otherwise the data is left in system memory to be grabbed across AGP when the window is maximized again. So iBook users and users of older TiBooks need merely minimize or hide things more often.
As a rough estimate, 16MB is 2048x2048 32-bit pixels, which is over four times the iBook's resolution and about four times the TiBook's, so just try to ensure that open windows wouldn't cover the screen completely more than four times. For a 32 MB user the threshold is obviously about eight screens worth of data.
It's possible that switching down to 16-bit colour will offer a significant increase in the number of windows that can be open before using system RAM, but it's more likely that the textures are always stored as 32-bit graphics internally anyway, and only the memory taken up by the final screen image would be thus decreased.