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 CAD / Development / Organizations / LDraw / 4730
    Re: L(EGO)Draw parts - 4th batch —Joshua Delahunty
   (...) The astute parts author will notice a slightly new format to these new files. I thought it might help to describe them. The first line is the official LEGO Group name for the part. These are almost always exclusively in UPPERCASE, so you'll (...) (14 years ago, 15-Sep-10, to lugnet.cad.dev.org.ldraw, FTX)
   
        Re: L(EGO)Draw parts - 4th batch —Philippe Hurbain
   There is one more thing to add to Joshua extensive explanations: coplanar triangle pairs are not assembled into quads. I advocated for that, because it offers the maximum flexibility when splitting into subparts or adjusting vertices position (no (...) (14 years ago, 16-Sep-10, to lugnet.cad.dev.org.ldraw, FTX)
   
        Why quads? Re: L(EGO)Draw parts - 4th batch —Timothy Gould
   (...) I realise this is largely off-topic to the oriinal thread but I've always been curious why the use of quads is encouraged when just about every other format and rendering engine sticks to triangles. So the part author merges triangles into (...) (14 years ago, 16-Sep-10, to lugnet.cad.dev.org.ldraw, FTX)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Philippe Hurbain
   (...) Good question! + reduces file size by 50% + 50% less vertices to adjust when building "by hand" + triangles plays havoc with smooth shading (the helical artefact that can be seen here (URL) disappears when triangles are converted to quads. But (...) (14 years ago, 17-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Travis Cobbs
   (...) Note that I consider this behavior to be a bug in LDView, and as such I will fix it when I get a chance. --Travis (14 years ago, 17-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Don Heyse
   (...) Isn't this the same problem we ran into with the twisted wedge bricks a while back? Those gave us problematic conditional lines in addition to the ugly zigzag shading artifacts. (URL) thought the solution was to orient the triangles orthogonal (...) (14 years ago, 18-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Travis Cobbs
   (...) algorithm. LDView uses Type 5 lines in the LDraw file for smoothing, and considers any two surfaces that have a Type 5 line joining them to be part of a smooth curve. The problem is that two co-planar triangles sitting next to each other (...) (14 years ago, 21-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Don Heyse
   (...) I see. So what you really want to do in LDView is ignore the Type 5 lines (at least for smoothing) and smooth wherever there's no Type 2 edge lines between the triangles (and quads). (...) Did anybody ever did actually fix the parts though? I (...) (14 years ago, 22-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Philippe Hurbain
     (...) Sorry for that ;o) But (fortunately) here are very few twisted surfaces in LEGO pieces, so I don't think my tool has created too much havoc... (...) Problem is that at this low level I have almost no information about the intended geometry - I (...) (14 years ago, 22-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Travis Cobbs
   (...) Actually, no. That is indeed a long-term goal, but it is hampered by two things. First of all, it's a lot of work. Secondly, the current algorithm is actually useful to part authors, since it can visually highlight missing conditional lines. (...) (14 years ago, 23-Sep-10, to lugnet.cad.dev.org.ldraw)
   
        Re: Why quads? Re: L(EGO)Draw parts - 4th batch —Don Heyse
   (...) Hmmm, it seems to me that any algorithm that can find the missing Type 5 lines (in order to create the dummy entries) should be able to find *all* of the Type 5 lines. Some missing lines is just a special case of all missing. So just include (...) (14 years ago, 23-Sep-10, to lugnet.cad.dev.org.ldraw)
 

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