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 CAD / Development / 2001
2000  |  2002
Subject: 
Re: fixes??
Newsgroups: 
lugnet.cad.dev
Date: 
Mon, 7 Jun 1999 06:55:06 GMT
Viewed: 
679 times
  
Luckily, you have access to the LDLite source code.
And it is the following lines near the top of stub.c:

// replace pixels within tolerance to avoid rounding problems
#define Z_LINE_TOLERANCE 2

// move lines closer to viewer before drawing to avoid rounding problems
#define Z_LINE_OFFSET 3

The z values are in 1/16ths of an LDRAW-unit.  The Z_LINE_TOLERANCE
is used in case one line is drawn exactly over another, so we make
sure the entire line is replaced rather than some moire pattern
due to rounding.  The Z_LINE_OFFSET works like the "Polygon
Offset".
Playing with these values makes some models look better at some
resolutions and angles. I typically adjust these so that the
file m928.dat by Steven "Wombat" Walter at the standard view
looks the best.  Maybe these need to be tweakable?
-gyug



Leonardo Zide wrote:

Steve Bliss wrote:

The problem is the primitive stud*.dat files are specifying two different
colors for the same voxel (3D pixel)--the voxels are the edges are being
filled with both the edge color and the surface color.  So the renderer has
to 'decide' which color to use.

Without making drastic changes in the LDraw language, there's not much that
can be done.  If the edges are 'cheated' (moved slightly above the surface
so they will alway be drawn), they will appear to float above the surface
at high resolutions.

  You don't need to change anything in the LDraw language, you can use
something called "Polygon Offset" (those who have used OpenGL will know
what I mean), it moves the lines a little bit to the front when checking
the Z-buffer. You'd just need to have access to the LDraw source code to
change that... :)

Leonardo



Message has 1 Reply:
  Re: fixes??
 
(...) Did you get the changes to the way LDLite saves bitmaps that I submited about 2 months ago ? You haven't told me anything. Leonardo (25 years ago, 7-Jun-99, to lugnet.cad.dev)

Message is in Reply To:
  Re: fixes??
 
(...) You don't need to change anything in the LDraw language, you can use something called "Polygon Offset" (those who have used OpenGL will know what I mean), it moves the lines a little bit to the front when checking the Z-buffer. You'd just need (...) (25 years ago, 2-Jun-99, to lugnet.cad.dev)

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