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 14:11:17 GMT
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Viewed:
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2698 times
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In lugnet.cad.dev.mac, Travis Cobbs wrote:
> Just out of curiosity, do you cache pieces once they have been loaded, so they
> only get loaded once? If not, you can speed things up rather enormously by
> doing so.
>
> --Travis Cobbs
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 400MHz computer can render
the 3104 bricks in 10 seconds or say 300 bricks per second. For comparison I
also have access to an IBM PC with a genuine PIII running at 450MHz using
Windows 98, MLCAD 3.0 requires 1:21 to load this file and can do a redraw in
about 9 seconds.
I don't wish to enter into a Mac vs PC comparison here, so lets just say both
systems seem to perform similarly.
There is a caveat with respect to speed though;
* Only bricks defined either internally (very fast) or in the "Parts" directory
are cached, inline or file defined bricks (eg 4696.dat, 32531.dat etc) are drawn
"on the fly" this gives quite heavy performance hits in MBC. I noticed this when
recompling Orion's original file (this behavior is deliberate). However as a
consolation, where a brick is subsequnetly added to the parts directory this
will be used in preference to the file listed part, thus giving an automatic
speed increase.
James has now informed me that a Dual 2GHz G5 loads in about 44 seconds and
renders the model in about 5 seconds. Likewise elsewhere on this thread Tom has
also indicated his findings.
What has my interest is two things,
1. As indicated before, load speeds seem to he restriced by the hard disc speed,
as the files are quite small, the critical item is access speed here rather than
transfer speed.
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.
Andrew...
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Message has 3 Replies:
 | | Re: Mac Brick CAD and the Imerial Star Destroyer
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| (...) I have a few comments--based on my experience writing LDView--that I think could improve your load performance. First of all, I believe what you are saying above (and a little later in your post) is that you only cache complete bricks. If this (...) (21 years ago, 17-May-04, to lugnet.cad.dev.mac)
| | | Re: Mac Brick CAD and the Imerial Star Destroyer
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| (...) 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 (...) (21 years ago, 17-May-04, to lugnet.cad.dev.mac)
| | | Re: Mac Brick CAD and the Imerial Star Destroyer
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| One thing I've forgotten to mention in my previous replies is that it's really unfair to compare the performance of an editor (MBC) with a viewer (LDView), even if both are running on the same machine. A viewer doesn't have to worry about adding, (...) (21 years ago, 17-May-04, to lugnet.cad.dev.mac)
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