Subject:
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Re: 3D Transformations Architecture Question
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Newsgroups:
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lugnet.cad
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Date:
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Fri, 13 Jul 2007 03:38:18 GMT
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Viewed:
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2152 times
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In lugnet.cad, Travis Cobbs wrote:
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Actually, based on what you write after the above, this is a “How do you draw
in 3D?” question, which is fairly close to “How do you do 3D?”. The
implementation details of how 3D gets drawn to the screen tend to answer all
your questions.
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Travis,
Thanks, but that answer is exactly what I was trying to avoid in this
discussion.
I understand about creating a transformation matrix, a camera matrix and a
projection/perspective matrix. I understand about compositing them all for a
final drawing transformation/2D projection. I have all of those routines built
and I know how to get the objects drawn on screen. I’m more concerned with the
most efficient way of generating/storing the data to get to the point of
drawing.
My question is whether or not calculation of those matrices and their final
transformation on all objects in the scene for any change is wise since software
of this type tends to have few simultaneously moving parts. It’s great for FPSs
where everything is in motion (via motion of the camera/player POV) and needs to
be updated constantly, but in a CAD environment when you have 100 objects on the
screen and are only rotating 1 of them on 1 axis (or worse, just translating it)
while the other 99 are static seems like an awful lot of muls (via matrix
compositing) for data which is not changing. I’m wondering whether or not it’s
better to not only store the last version of the trans/cam/proj matrices but
also any object vertex data which is not modified by the latest change as well.
J
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Message has 1 Reply:
 | | Re: 3D Transformations Architecture Question
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| (...) Sorry. I guess I didn't fully understand why you wanted to do the pre-multiplies. Hopefully this reply will be closer to what you are looking for. LDView 1.0 did exactly what you suggest. It calculated the final coordinates for every single (...) (17 years ago, 13-Jul-07, to lugnet.cad, FTX)
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Message is in Reply To:
| | Re: 3D Transformations Architecture Question
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| (...) Actually, based on what you write after the above, this is a "How do you draw in 3D?" question, which is fairly close to "How do you do 3D?". The implementation details of how 3D gets drawn to the screen tend to answer all your questions. When (...) (17 years ago, 13-Jul-07, to lugnet.cad, FTX)
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