I have experienced similar problems. The Situation was slightly different. I was doing a large BitBlt (no fomat translation though). A 640 x 480 x 16bit BitBlt took 14 Million clock cycles on a TNT system.

Grabbing the desktop surface and memcopying the data took 8 Million.

On one i740 system the BitBlt takes 1 Million clock. Usual range for systems is 3-6 Million.

I'm about to try a new version of the code tonight to test directdraw blt performance on the TNT.

I have found that it is DirectDraw's Clipper that is slow on the TNT. I disabled it, and the program ran fast. I will just write my own clipper. Anybody else notice the clipper is slow on TNTs? Anybody know where you can get a list of what video cards support what features of DirectDraw? It seems if use use certain features on certain cards they either crawl or don't work, while they work fine on others. I know I can Enumerate the Caps, which I will do, but I am just wondering if there's a list somewhere, so I have an idea of how much I will have to recode myself.

-Gilderoot

I remember on my Elsa Victory Erazor with the old Riva chipset you can choose how much of the systemmemory can be controlled by the graphics-accelerator, maybe it's got something to do with that.

CU

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Skullpture Entertainment
#40842461

I have a V550.

I haven't played with it a lot, but it seems like the clipper is, in fact, a dog on the TNT.

If you find anything else out, let me know.

Mason McCuskey
Spin Studios
www.spin-studios.com

I wrote some game engine code.. 4 way scrolling tiles in DX6. I had an old ATI AllInWonder (Rage II chip, I think), and it ran fine (about 35 FPS, including some extra FX). I just upgraded my vid card to a NVidia TNT (Creative Labs), and my framerate dropped to 3 FPS!!!!! The engine fills the screen w/ 40x40 tiles (Blt function). I took out this part, and it the routines run very fast, so I figure maybe the Blitting is slow.. but I don't know why. It was plenty fast on an old card. Any ideas? Anyone had this problem?

Thanks,
-Gilderoot

If the clipper is such a big pain in the b*t, why waste time worrying about it - write your own. It's similar to the performance issues of memset() - OK it's dead slow, but, hell, how hard is it to write your own.

This is really a general issue about software development and code re-use. It is frequently a lot faster to do your own stuff than attempt to use something that may or may not work (or something that only partly solves your problem). Unless the problem at hand is very complex, 3rd party software is, in general, more trouble that it's worth.

My experience with DX tells me that it's good for getting HW independent access to the framebuffer og HW blitting (and setting screen modes), but that's about it.

Same goes for DirectPlay, DirectMusic, Direct3D etc.: attempt to use any but the very core functions and you're f*cked.

Just my opinion...

/NJ