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Subject: 
Re: Conditional lines on sloped wedge parts 43720 and 43721
Newsgroups: 
lugnet.cad.dat.parts
Date: 
Mon, 25 Apr 2005 14:52:13 GMT
Viewed: 
4862 times
  
In lugnet.cad.dat.parts, Niels Karsdorp wrote:
In lugnet.cad.dat.parts, Lars C. Hassing wrote:
In lugnet.cad.dat.parts, Steve Bliss wrote:
I'm pretty sure that's going to be the problem with *any* partition
of this surface into polygons.  Having a mathematical description
of the surface would be good, because then we could potentially
create a primitive for the surface, and rendering programs could
substitute a smooth-curve construct for the primitive.

I have made a 43720.inc for the test of the coming L3PPARTS.
The mathematical description of the surface is:
    80x + 40y + yz = 0
and I have used the POV primitive quadric:
    quadric {
       <0,0,0>, <0,0,1>, <80,40,0>, 0
       clipped_by { box { <-20,0,-40>, <0,20,40> } }
    }

Looks good.
Should we create a new primitive with the next dimensions:?
2 24 0 0 1 0 1 1
2 24 1 0 -1 0 1 -1
2 24 0 0 1 1 0 -1
2 24 0 1 1 0 1 -1
and a POV-quadric version in the coming L3PPARTS.

As the outer twisted surface of the parts with this shape are
pretty the same size, the inner surface differs among these parts
(in 43720/43721 the inner surface has a z-size of 72,
in 45407 the inner suface has a z-size of 76).
With a general primitive it can be stretched to any dimension.

Nice, I like the idea of the quadric primitive, but we want to
add some curvature to the LDRAW version, right?  I fiddled a bit
with the part a few days ago, starting with the two triangles
outlined by your primitive.  I didn't exactly finish, but I think
if you take this and make a surface that follows the green X and
also follows the red stripes, you end up with something pretty
decent where the optional lines work.

Don




0 Wedge  4 x  2 Sloped Left
0 Name: 43721.dat
0 Author: Donald Sutter
0 LDRAW_ORG Part UPDATE 2004-04
0 Unofficial hack for testing purposes.
0
1 16 -10 0 30 0 0 1 0 1 0 -1 0 0 stud.dat
1 16 -10 0 10 0 0 1 0 1 0 -1 0 0 stud.dat
1 16 -10 0 -10 0 0 1 0 1 0 -1 0 0 stud.dat
1 16 -10 0 -30 0 0 1 0 1 0 -1 0 0 stud.dat
0
2 4 5 20 -20 0 0 -20
2 4 10 20 0 0 0 0
2 4 15 20 20 0 0 20
0
2 2 0 20 -40 3.75 15 -20
2 2 3.75 15 -20 5 10 0
2 2 5 10 0 3.75 5 20
2 2 3.75 5 20 0 0 40
0
2 2 0    0  -40  1.25 5  -20
2 2 1.25 5  -20  5    10 0
2 2 5    10 0    11.25 15  20
2 2 11.25 15 20   20   20  40
0
3 46 0 0 -40 0 20 -40 3.75 15 -20
3 46 0 0 -40 3.75 15 -20 5 10 0
3 46 0 0 -40 5 10 0 3.75 5 20
3 46 0 0 -40 3.75 5 20 0 0 40
0
3 45 20 20 40 0 20 -40 3.75 15 -20
3 45 20 20 40 3.75 15 -20 5 10 0
3 45 20 20 40 5 10 0 3.75 5 20
3 45 20 20 40 3.75 5 20 0 0 40
0
1 16 0 0 0 -1 0 0 0 1 0 0 0 1 s\43720s01.dat
0



Message has 1 Reply:
  Re: Conditional lines on sloped wedge parts 43720 and 43721  [DAT]
 
(...) The following are the appropriate conditionals for Don's surface. Playing with it you can have angles where the conditionals seem to go too far, but it's certainly much better than the current ones. (Note that the last 4 conditionals are only (...) (20 years ago, 26-Apr-05, to lugnet.cad.dat.parts)

Message is in Reply To:
  Re: Conditional lines on sloped wedge parts 43720 and 43721  [DAT]
 
(...) Looks good. Should we create a new primitive with the next dimensions:? 2 24 0 0 1 0 1 1 2 24 1 0 -1 0 1 -1 2 24 0 0 1 1 0 -1 2 24 0 1 1 0 1 -1 and a POV-quadric version in the coming L3PPARTS. As the outer twisted surface of the parts with (...) (20 years ago, 25-Apr-05, to lugnet.cad.dat.parts)

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