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Subject: 
Re: Conditional lines on sloped wedge parts 43720 and 43721
Newsgroups: 
lugnet.cad.dat.parts
Date: 
Wed, 22 Sep 2010 03:37:20 GMT
Viewed: 
19892 times
  
In lugnet.cad.dat.parts, Lars C. Hassing wrote:
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.

Good idea with a twist primitive (twist.dat ?).
Perhaps it would be simpler if it were only in one octant:
    2 24 0 0 0  0 0 1
    2 24 0 0 1  1 1 1
    2 24 1 1 1  0 1 0
    2 24 0 1 0  0 0 0
POV code would be:
    //x - yz = 0
    quadric {
       <0,0,0>, <0,0,-1>, <1,0,0>, 0
       clipped_by { box { <0,0,0>, <1,1,1> } }
    }
/Lars

Ok so it's been a few years, but I took another look at this.
Did anybody ever make a twist primitive?  It appears like all
you need to do is something like this.

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 0 0 0 -1 0 0 0 1 0 0 0 1 s\43720s01.dat
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
0 // Begin 4 quadrant twist patch.
0 // Is each quadrant actually the same part?
0 // Scale down to 1x1 for reuse in other parts.
0 // Can break each quadrant into 4 parts for
0 // an even finer mesh.
3 16   11.25 15 20   5 10 0    10 20 0
3 16   11.25 15 20   10 20 0   20 20 40
3 16   11.25 15 20   20 20 40  10 10 40
3 16   11.25 15 20   10 10 40  5 10 0
0
3 16   3.75 5 20     0  0  0   5 10 0
3 16   3.75 5 20     5 10 0    10 10 40
3 16   3.75 5 20     10 10 40  0 0 40
3 16   3.75 5 20     0 0 40    0 0 0
0
3 16   1.25 5 -20    0 0 -40   0 10 -40
3 16   1.25 5 -20    0 10 -40  5 10 0
3 16   1.25 5 -20    5 10 0    0 0 0
3 16   1.25 5 -20    0 0 0     0 0 -40
0
3 16   3.75 15 -20   0 10 -40  0 20 -40
3 16   3.75 15 -20   0 20 -40  10 20 0
3 16   3.75 15 -20   10 20 0   5 10 0
3 16   3.75 15 -20   5 10 0    0 10 -40
0 // End 4 quadrant twist patch.
0



Message has 1 Reply:
  Re: Conditional lines on sloped wedge parts 43720 and 43721  [DAT]
 
(...) Very interesting! (URL) I am not so much comvinced by the improvement for flat shading. Looks like we trade triangular artefacts in one direction with artefacts in the other one. But it drastically improves the very ugly condlines artefacts! (...) (14 years ago, 22-Sep-10, to lugnet.cad.dat.parts, FTX)

Message is in Reply To:
  Re: Conditional lines on sloped wedge parts 43720 and 43721  [DAT]
 
(...) Good idea with a twist primitive (twist.dat ?). Perhaps it would be simpler if it were only in one octant: 2 24 0 0 0 0 0 1 2 24 0 0 1 1 1 1 2 24 1 1 1 0 1 0 2 24 0 1 0 0 0 0 POV code would be: //x - yz = 0 quadric { <0,0,0>, <0,0,-1>, (...) (19 years ago, 27-Apr-05, to lugnet.cad.dat.parts)

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