Subject:
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Re: Linetype 5 Help?
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sat, 9 Sep 2000 00:08:07 GMT
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Viewed:
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893 times
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Not having actually created any parts, I can't guarantee that the
information below is correct. However, my understanding of linetype 5 is
that you will normally use adjacent points in your overall curved shape for
the two extra points. This is easy as long as your curve is only in one
dimension (like a cylinder), but may be more difficult for curves in more
dimensions (like a sphere). I'll use a half cylinder as an example, seen
from the side (use your imagination, and view this with a fixed-width font;
copy and paste into a text editor if you have to):
Y
^
| AC E G IK
| ++--+---+--++
| || | | ||
| || | | ||
| || | | ||
| ++--+---+--++
| BD F H JL
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+------------->X
Note that the horizontal axis of the figure above is X and the vertical axis
is Y. Z is of course not drawn. This matches the axes of the cylinder
primitives in LDraw.
First off, only the vertical lines will be of type 5, since the horizontal
ones should always be drawn, and therefore type 2. Type 5 lines only get
used on edges perpendicular to the curve (or all edges for a sphere). I'll
start with an easy example. For the type-5 line between E and F, you can
just use C and G as the extra points. G-H would use E and I as the extra
points.
This works for all the above except for A-B and K-L. For these two you have
to create a new point. So, for A-B, you would use C as one of the extra
points, and a new point whose X and Y coordinates are the same as C, and
whose Z coordinate is the C's Z coordinate times -1.
Calculating that extra point is more difficult for an arbitrary curved
surface, but in general you want to continue with the curve for one more
facet, and use a coordinate from that facet for the point. This extra facet
is of course not included in the dat file.
Does this help?
--Travis Cobbs (tcobbs@san.REMOVE.rr.com)
"Dave Schuler" <orrex@excite.com> wrote in message
news:G0KLuF.8FM@lugnet.com...
> Is there a brief how-to available on the deployment of this linetype? I • am
> endlessly befuddled in my efforts to use it successfully, and I feel like • I'm
> missing something simple!
>
> Dave!
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Message is in Reply To:
 | | Linetype 5 Help?
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| Is there a brief how-to available on the deployment of this linetype? I am endlessly befuddled in my efforts to use it successfully, and I feel like I'm missing something simple! Dave! (24 years ago, 8-Sep-00, to lugnet.cad.dev)
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