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 DirectDraw 
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Joined: Thu Apr 11, 2002 7:01 am
Posts: 7
Post DirectDraw
I just had a couple questions about DirectDraw, I'll try to make it short [img]images/smiles/icon_smile.gif[/img]

1. If a surface (plain/backbuffer) is in system memory it doesn't require a Lock/Unlock to access, correct? Atleast not in the sense that the VRAM surfaces have to be locked?

2. Is there any hardware acceleration when blitting a surface in system memory to a surface in video memory? I'm guessing there must be since most blitting will be images/sprites to the back buffer.


Wed Jul 30, 2003 4:43 pm
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Joined: Thu Apr 11, 2002 7:01 am
Posts: 7
Post DirectDraw
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote
Quote:
You should still lock/unlock it. Under-the-hood, there is less of a reason for it in system RAM, but there are still no guarantees that windows will always let you get away without locking/unlocking them. Even if it works now, it may not later on (maybe in a future ver of windows).


Mmm, well, that goes against basic logic. It's like saying your pointer to dynamically allocated data might randomly become invalid. Please, don't misunderstand, I don't mean to argue, but I hate doing things if I don't really have to.


<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote
Quote:
I think there are AGP cards that do system-to-video and video-to-system accel (I've never heared of a system-to-system accel, that would be silly) Although, most of the time you would want as many of the sprites/etc as you can to be stored in video ram instead of system ram, because video ram to video ram transfers are faster.


Ok, so you're sure blitting hardware isn't equiped for System to Video blits?

Thanks for you help [img]images/smiles/icon_smile.gif[/img]

[ July 30, 2003: Message edited by: Xanth ]</p>


Thu Jul 31, 2003 12:26 am
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Joined: Fri Sep 24, 1999 7:01 am
Posts: 18
Location: Cleveland, OH
Post DirectDraw
1. You should still lock/unlock it. Under-the-hood, there is less of a reason for it in system RAM, but there are still no guarantees that windows will always let you get away without locking/unlocking them. Even if it works now, it may not later on (maybe in a future ver of windows).

2. I think there are AGP cards that do system-to-video and video-to-system accel (I've never heared of a system-to-system accel, that would be silly) Although, most of the time you would want as many of the sprites/etc as you can to be stored in video ram instead of system ram, because video ram to video ram transfers are faster.

[ July 30, 2003: Message edited by: Abscissa ]</p>


Thu Jul 31, 2003 6:34 am
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