Subject:
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Re: Mac Brick CAD and the Imerial Star Destroyer
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Newsgroups:
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lugnet.cad.dev.mac
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Date:
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Mon, 17 May 2004 18:01:01 GMT
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Viewed:
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2062 times
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In lugnet.cad.dev.mac, Andrew Allan wrote:
> 2. Redrawing is far more interesting as all drawing is handled by OpenGL using
> OpenGL lists. To draw a part I load the part orientation matrix into OpenGL and
> then call the list. Originally I theorised that more recient graphic cards with
> OpenGL hardware acceleration would have loaded the lists into the RAM memory
> present on the card and then drawn them directly, big speed advantage. But
> practice isn't bearing this out since there seems to be very little drawing
> speed differences. So I need to figure how Apple handles OpenGL with respect to
> lists.
Your expectation is certainly justified. I don't know what the driver
architecture is on the Mac, but I suspect that the video hardware manufacturers
are responsible for the OpenGL implementation for their own hardware, just like
on the PC. If this is the case, then it is ATI that's responsible for doing the
right thing with the data (or not doing the right thing).
I can say that on the PC side, it appears that at the very least the geometry
encompassed by the display lists gets downloaded into video RAM. If I turn off
conditional edge lines, the model renders reasonbly fast (on the order of 10fps,
IIRC) in my next-gen LDView. (Yes, that's fps, not spf.) The current LDView
has memory issues that slow it down, and I'm not sure what its speed is.
Just out of curiosity, how are you drawing your geometry? On ATI hardware on
the PC, I think vertex arrays are faster than OpenGL 1.0 glVertex calls, even
when encapsulated inside a display list. This doesn't seem to be the case on
nVidia hardware on the PC. (It might also not be the case with recent ATI
drivers.)
--Travis Cobbs
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Message has 1 Reply:
 | | Re: Mac Brick CAD and the Imerial Star Destroyer
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| (...) Travis Having done some experiments and research over the last couple of days, it seems that to get very fast drawing in OpenGL generally, vertex arrays are necessary. OpenGL has specific commands such as glBufferDataARB that will explicitly (...) (20 years ago, 20-May-04, to lugnet.cad.dev.mac)
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Message is in Reply To:
| | Re: Mac Brick CAD and the Imerial Star Destroyer
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| (...) Yes, When loading I make a list of all the unique bricks in the model (colour and type) these are then cached as OpenGL lists of so when drawing, I then just call the various OpenGL lists. For the imperial star destroyer, this means even a (...) (20 years ago, 17-May-04, to lugnet.cad.dev.mac)
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