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Subject: 
Overlapping primitives - a reason to Hold a part?
Newsgroups: 
lugnet.cad.dat.parts
Date: 
Sat, 15 Jul 2006 13:41:06 GMT
Viewed: 
3075 times
  
What is the policy on overlapping primitives in a part?  Is it OK?  Is it
frowned upon?  Is it accepted as the norm?  Is it only accepted under
exceptional circumstances?  It excessive over-lapping of primitives (or
quads/tris) a reason to Hold a part?  Is any over-lapping (beyond the
exceptional) a reason to Hold the part?

For example, the 4 primitives used here
http://www.brickshelf.com/gallery/whoward69/LDraw/parts/primitives/prim-overlap1.jpg
correctly define the inner and outer edges of the part.  But is the use of the
4-4ndis (green) acceptable as only a tiny portion (see here
http://www.brickshelf.com/gallery/whoward69/LDraw/parts/primitives/prim-overlap2.jpg)
of it is actually required.

thanks

William



Message has 5 Replies:
  Re: Overlapping primitives - a reason to Hold a part?
 
(...) I've been running into problems with this when designing parts and also when looking at primitive substituted versions of parts featuring parts of circles. In terms of appearance sometimes it would be much better to overlap some primitives or (...) (18 years ago, 15-Jul-06, to lugnet.cad.dat.parts)
  Re: Overlapping primitives - a reason to Hold a part?
 
(...) I have used similar techniques a few times now, and the parts have not been held because of it. As far as rendering, most programs seem to be able to handle it ok, so I don't think it should be a reason to hold the part. ROSCO (18 years ago, 15-Jul-06, to lugnet.cad.dat.parts)
  Re: Overlapping primitives - a reason to Hold a part?
 
(...) I don't know what the policy is (or if there is one), but I will point out that it will likely cause artifacts in any transparent parts in any viewer that supports blended transparency (such as LDView). The overlapping sections will get drawn (...) (18 years ago, 16-Jul-06, to lugnet.cad.dat.parts, FTX)
  Re: Overlapping primitives - a reason to Hold a part?
 
(...) In my other message, I indicated that overlapping polygons will be visible on transparent parts in viewers such as LDView. However, if it is decided that they are ok, it seems to me that you'd be much better off in this instance just using a (...) (18 years ago, 16-Jul-06, to lugnet.cad.dat.parts)
  Re: Overlapping primitives - a reason to Hold a part?
 
(...) Travis and Guy have covered the two major issues with overlapped surfaces. As a parts-admin, my view is that while it is better to not overlap surfaces, in some cases the complications required to avoid overlapping are not worth it. So it (...) (18 years ago, 16-Jul-06, to lugnet.cad.dat.parts)

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