Subject:
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Type-5 conditional edge line
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sat, 1 Apr 2000 22:10:42 GMT
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Highlighted:
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(details)
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Viewed:
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1392 times
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I have a question about the type-5 conditional line. Assume I have four
points in 3d space like this:
(If you're reading LUGNET via the web interface, you must push "view raw
message" to see my ASCII art.)
1---2
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4---3
Except that the points are _not_ in the same plane. This is difficult
to illustrate with ASCII, so you'll have to trust me! ;-)
Now, let's say I use two triangles to fill out the surface between the
points like this:
1---2
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|/ |
4---3
The code for the triangles would be something like this:
3 16 x1 y1 z1 x2 y2 z2 x4 y4 z4
3 16 x2 y2 z2 x3 y3 z3 x4 y4 z4
But I also need a conditional edge line along the diagonal. I only have
information about the four said points, so my question is this: Will a
type-5 line like this work?
5 24 x2 y2 z2 x4 y4 z4 x1 y1 z1 x3 y3 z3
It does work in L3Lab (as far as I can see), but I wonder if it actually
follows the standard. I find the type-5 lines a bit confusing.
Fredrik
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Message has 2 Replies:
 | | Re: Type-5 conditional edge line
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| Fredrik Glöckner <fredrik.glockner@bio.uio.no> wrote in message news:m3pus9zd3x.fsf@...ldomain... (...) It looks good to me. I'm pretty sure this is how it is done on the sphere primitives. -John Van (24 years ago, 3-Apr-00, to lugnet.cad.dev)
| | | Re: Type-5 conditional edge line
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| In lugnet.cad.dev, Fredrik Glöckner wrote: [snippety] (...) Yes, your conditional line should be fine. When the triangles are viewed like: 4 /|\ / |.3 / .| /. | 2----1 points 1 and 3 are on the same side of the 2-4 line, so the conditional line will (...) (24 years ago, 3-Apr-00, to lugnet.cad.dev)
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