Moving data from ram to the video card during gameplay

SDL Development
1

I’m still thinking of trying OpenGl for my Fallout/Baldurs Gate type game. I
was thinking that you could load all the graphics into ram
and store them in special buffers. Then you could load the graphics in the
ram buffers onto the video card when they are about to appear in the view
port. At the same time you can release the unseen graphics from the cards
memory. I was wondering (as I don’t know much about hardware) if this
affects video cards in any way apart from a
temporary slowdown during the load/release process? Has anyone tried this
method and was it successful?_________________________________________________________________
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2

Hi there,

I have a problem using OpenGl. I render a very simple scene (as a working
model for the future game scene) with only the standard GlutTeapot, some
GlutCubes and a simple lighting model with just one light. I use a Celeron
600, a Matrox 400 graphics card and Mandrake 8.1 with XFree 4.1.0 with
hardware acceleration. When i just render this scene in a infinite loop the
framerate I get is only 20-something fps. This is not enough for a game and i
haven’t even started the big explosions, OpenAL sound etc. I hope someone can
give me some advice and show me some tricks to speed things up.

Thanks for reading,
Mattijs de Groot
Amsterdam

3

g400s are slow anyhow. if you are doing 32bit modes, use 400x300 as the res, or 640x480 for 16 bit modes. This is all assuming you’re actually using hardware accelerationOn 21-Dec-2001, mdg wrote:

Hi there,

I have a problem using OpenGl. I render a very simple scene (as a working
model for the future game scene) with only the standard GlutTeapot, some
GlutCubes and a simple lighting model with just one light. I use a Celeron
600, a Matrox 400 graphics card and Mandrake 8.1 with XFree 4.1.0 with
hardware acceleration. When i just render this scene in a infinite loop the
framerate I get is only 20-something fps. This is not enough for a game and i
haven’t even started the big explosions, OpenAL sound etc. I hope someone can
give me some advice and show me some tricks to speed things up.

Thanks for reading,
Mattijs de Groot
Amsterdam

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4

I’m still thinking of trying OpenGl for my Fallout/Baldurs Gate type
game. I was thinking that you could load all the graphics into ram
and store them in special buffers. Then you could load the graphics in
the ram buffers onto the video card when they are about to appear in
the view port. At the same time you can release the unseen graphics
from the cards memory.

Texture caching! It’s used heavily in many 3D games, so you should be
able to find articles on it. (I’ve seen at least one, but I can’t
remember where I found it…)

BTW, it seems like most OpenGL implementations do this automatically if
there’s not enough texture RAM for your textures - but of obviously,
OpenGL can’t know when you need a texture before you actually bind it
while in the middle of rendering the next frame! That might be a bit late
if you end up needing several hundred kB of “swapped out” textures to
render a frame, and texture transfers are slow…

I was wondering (as I don’t know much about
hardware) if this affects video cards in any way apart from a
temporary slowdown during the load/release process?

I don’t think so - but this “temporary slowdown” might be quite
substantial with some drivers. For cards/drivers that can’t use busmaster
DMA, it might be a good idea to implement a per-frame “texture transfer
quota”. (Use glTexSubImage2D() if a single texture exceeds the quota.)

Has anyone tried this method and was it successful?

It’s a common technique in 3D, so it seems to be working pretty well.

//David Olofson — Programmer, Reologica Instruments AB

.- M A I A -------------------------------------------------.
| Multimedia Application Integration Architecture |
| A Free/Open Source Plugin API for Professional Multimedia |
----------------------------> http://www.linuxdj.com/maia -' .- David Olofson -------------------------------------------. | Audio Hacker - Open Source Advocate - Singer - Songwriter |-------------------------------------> http://olofson.net -'On Friday 21 December 2001 21:45, David Moffatt wrote: