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Aardvajk

Old DirectDraw code

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I asked some questions about this last week but, despite lots of help, didn't really get anywhere so I'd like to rephrase my question slighly differently: Should old Direct3D code work as well on a newer PC/graphics card? Is the reason that my Direct3D4 game developed on my 98 machine slows to a crawl on newer PCs more likely to be due to a specific problem on the newer computers I have tested it on (XP and 2000) or do I have to resign myself to upgrading to Direct3D9 to write stuff for XP and 2000? Thanks.

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I don't know of any specific/definite reason why older code won't work at the same speed - but you have changed a huge number of variables (OS, drivers, hardware...) such that it's not surprising it has different characteristics.

Have you actually profiled the application and found the D3D stuff to be the slow part? It's possible that other libaries (or use of an older (presumably) non-unicode Win32 API) have a much higher overhead and/or have been deprecated.

I forget the details, but I have heard it mentioned a few times that older (say, pre-DX7) are emulated by remapping interfaces to a newer (and supported) version of Direct3D. Reduces the workload for respective companies...

Also, as I mentioned in your previous thread - backwards compatability, to my knowledge, makes no assertions regarding performance. It just states that it will still work [smile]

hth
Jack

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Quote:
Original post by jollyjeffers
I forget the details, but I have heard it mentioned a few times that older (say, pre-DX7) are emulated by remapping interfaces to a newer (and supported) version of Direct3D. Reduces the workload for respective companies...

hth
Jack


Windows XP contains new DX runtimes that will map anything pre DX7 to the DX7 „Device Driver Interface“ (DDI). This will save driver developers from some work.

We will se the same again with vista that will map anything pre DX9 to the DX9 DDI. Additional any Fixed Functions will be mapped to shader code if the card supports Shader Model 3. Makes driver development easier again.

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Thanks for that information. I know about the Pre-DX9->DX9 remapping in Vista, but wasn't 100% sure if/how that appeared under XP [smile]

Cheers,
Jack

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Must admit, I haven't profiled to ensure it is the graphics stuff directly although I did find using DirectDraw7 that if I ran it in emulation only mode it ran very fast indeed but graphics quality was a bit rubbish so had assumed from that that it must be the graphics hardware slowing it down.

Suppose it is possible that the three XP and 2000 machines I've tried on just have rubbish graphics cards. 32meg SiS 741 any good?

Going to give up for now and just write quality 98 software. Doubt anyone else will ever play it anyway. Thanks for all your help. I'll shut up about this now :)

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