 | | Part 41770 certified but missing sub-file??
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I recently downloaded the latest batch of parts from the LDraw Parts Tracker, and found three parts that were missing sub-files. Part 41769.dat & 41770.dat (Wing 2 x 4 Left/Right) both require sub-part s/41770s01.dat, but the sub-file isnt listed on (...) (19 years ago, 25-Apr-05, to lugnet.cad.dat.parts)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) 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>, (...) (19 years ago, 25-Apr-05, to lugnet.cad.dat.parts)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) I think the key difference is the twisted nature of this surface. I think the twist makes it impossible to partition the surface into polygons without having a mix of convex and concave seams. I'd like to be proven wrong. I don't have one of (...) (19 years ago, 19-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) Oh, I don't know about that 1 pixel business. The problem with the surface as it's currently written, is that it flip-flops between convex and concave every at every triangle. But if you ignore the triangles and spin the surface around a bit, (...) (19 years ago, 19-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) 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 (...) (19 years ago, 19-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) OK, I tried it and realise now that it doesn't solve the problem at all, just moves the outside curves to a different spot. I think Don is right, a more complex torus-like curve is necessary to represent it properly. ROSCO (19 years ago, 18-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) Well, I thought about this, and what I would try is changing the polygons thus: If the top points are A1-5 and the bottom points are B1-5, keep the A2-B1, A3-B2 as currently, but instead of A2-B2 etc, use A3-B1, A4-B2, etc. I think that would (...) (19 years ago, 18-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) I'm not sure about that. The surface as it's written is extremely lumpy, and the conditional lines work as expected given the lumps in the surface. You also get an ugly shading effect with flat shading because of those lumps. (URL) There's (...) (19 years ago, 18-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Re: Conditional lines on sloped wedge parts 43720 and 43721
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(...) I don't think it's the control points. I took a quick look at the file, actually just one of the lines, the first in the file. The control points used are the two unattached vertices from the triangles adjacent to the conditional edge. That (...) (19 years ago, 18-Apr-05, to lugnet.cad.dat.parts, FTX)
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| | Conditional lines on sloped wedge parts 43720 and 43721
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Wedge part 45407 (Wedge 4 x 4 with 1 x 4 Side Plates) has similar sloped sides as wedge parts 43720 and 43721 [LDrawPart 43721]. When I examined these parts in LDView, I noticed that the control points for the conditional lines on the sloped surface (...) (19 years ago, 16-Apr-05, to lugnet.cad.dat.parts, FTX)
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