Lines not on edges


Lines not on edges
#1
Is there some rule or recommendation against lines (type 2) not matching real edges of triangles or quads?

With this, I mean, for instance, lines that pass through some vertices, such as a line between (0,0,0) and (2,0,0), when the polygon's edges are (0,0,0)-(1,0,0) and (1,0,0)-(2,0,0). Or a set of lines that simply draw a figure inside a polygon.

Are these allowed or should I split the polygons or lines so that every line matches an actual polygon edge?
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Re: Lines not on edges
#2
I don't completely understand what you have in mind: a type 2 line is supposed to highlight a break forming an edge. This should not happen in a polygon since they are flat?
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Re: Lines not on edges
#3
I'm talking about the small rectangles drawn on the sides of 4771.dat (which has several other problems). These are showing a poorly modelled feature of the real piece, I'm afraid, but assuming they are OK, would it be allowed to model the whole side as a single rectangle and just draw the small ones inside?
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Re: Lines not on edges
#4
Got it. Yes, if you don't want to rewrite the part extensively, it should be OK as you described. But, in order of preference and complexity)...
- draw small line rectangle on top of big quad
- Separate use a rect primitive for the small rectangle, and properly build the surface around it (this is more or less what is presently done)
- Go one step further and separate the parts that make up this assembly.
For the record: Top part is 4771, bottom part (with latches that go through the rectangular holes) is 4772. Trans clear bulbs over lamps are 4769. Complete assembly is 73664.

...good luck on this one, there is (large) room for improvement Wink
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Re: Lines not on edges
#5
I have found in our specs at two places information about this:

File Format 1.0.2
Line type 2 can also be used to represent fine detail in patterns (cf some torso patterns) and when used in this manner any colour may be used for the line. In either case it should be remembered that not all renderers display line types 2 and 5.

Official Library Specification for Sticker Parts
Since edges are forbidden in sticker parts, colour 24 is not allowed.

So I understand both documents in the following way:
Usage of lines in another matter than egdes is not forbitten, only in sticker parts if they are submitted to the PT.
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Re: Lines not on edges
#6
The document you mention is outdated AFAIK.

Lines nowadays should not be used anymore to "enhance" a pattern;
instead finer modeling of it should be done.
In fact, we have removed such lines from plenty of e.g. Minifig torso parts in the recent couple of releases,
and I like this practice, because I always felt the lines being a kind of "mockup".
Nowadays, lines only are what they are: lines. No other purposes.
Maybe we need to update our specs. Chris? LSC?


PS: Edit:
Ah, we still have ONE exception, and that's the LEGO logo for the logo'ed studs variant, by Paul Easter.
I loved this file from its origin, and still do, some ten years later. This special file allows to quickly render
a LEGO logo onto studs in tools, without having big cannons like texture mapping etc.pp.
I would very much favor allowing this exception.
http://www.ldraw.org/cgi-bin/ptdetail.cgi?s=logo.dat
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Re: Lines not on edges
#7
Interesting thing about the different parts... I think I have 4771 and 4769 done. Where did you get the part numbers, and where can I get the corresponding ones for other light&sound bricks?

About the bottom part (4772), should I try to model the metal plates as 3D components or simply 2D silver areas would be enough?

Maybe this should go in a different thread, though.
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