Subject:
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Re: 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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Mon, 3 Apr 2000 16:34:54 GMT
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Highlighted:
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(details)
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1748 times
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In lugnet.cad.dev, Fredrik Glöckner wrote:
[snippety]
> 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.
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 be drawn. Also use this case for where either point 1 or
point 3 lie on the 2-4 line.
When the triangles are viewed like:
1----2
| /|
| / |
| / |
|/ |
4----3
points 1 and 3 are on opposite side of the 2-4 line, so the conditional
will *not* be drawn.
These cases fit the definition for conditional lines, so you're OK.
Steve
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Message is in Reply To:
 | | Type-5 conditional edge line
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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 | | | | | | 4---3 Except that the (...) (25 years ago, 1-Apr-00, to lugnet.cad.dev)
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