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Subject: 
Re: Colinear Vertices
Newsgroups: 
lugnet.cad
Date: 
Thu, 11 Dec 2008 14:47:47 GMT
Viewed: 
6056 times
  
If they're on a curved surface, you'll get higher quality out of LDView half the
time if you split them into triangles.  (I say half the time, because OpenGL
splits them into triangles in order to render them, and half the time they'll be
split the "right" way, and the other half the "wrong" way.)  If the split ends
up with one tiny triangle and one much bigger triangle, the smooth shading ends
up looking wrong in some circumstances.  Note that this will happen when LDView
doesn't decide that they're co-linear.  If LDView decides that they're
co-linear, it will simply convert the quad into a triangle (with the associated
T-junction).


Thanks, Travis. BTW, are there guidelines for part authors that would improve
smooth shading?

What about precision in coincidence between conditional lines and matching
polygon sides? I have seen _many_ instances where a quad should blend into a
primitive thanks to a well placed condline, but doesn't - I guess because of
precision issues during primitive scaling/rotation.

Similarly, assembling mirrored subparts that should form a smooth surface work
well, but if they are rotated I generally see the seam since there is rounding
error, and condline smoothing doesn't happen.

Philo



Message has 1 Reply:
  Re: Colinear Vertices
 
(...) Not that I know of. I'll think about adding a page to the LDView web site. (I don't think it's really appropriate to add it to ldraw.org, since it's LDView-specific.) (...) The precision is 0.0001. I multiply the coordinate by 10000 and then (...) (16 years ago, 11-Dec-08, to lugnet.cad)

Message is in Reply To:
  Re: Colinear Vertices
 
(...) If they're on a curved surface, you'll get higher quality out of LDView half the time if you split them into triangles. (I say half the time, because OpenGL splits them into triangles in order to render them, and half the time they'll be split (...) (16 years ago, 9-Dec-08, to lugnet.cad)

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