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Special: 
[DAT] (requires LDraw-compatible viewer)
Subject: 
Re: Quick way to mirror-image a model?
Newsgroups: 
lugnet.cad
Date: 
Thu, 17 Jun 2004 20:23:36 GMT
Viewed: 
2193 times
  
In lugnet.cad, Dave Schuler wrote:
In lugnet.cad, Carl Nelson wrote:
In lugnet.cad, Dave Schuler wrote:
For simple mirroring of the parts from left-to-right.  This only works for parts
oriented along the X, Y, and Z axes.  If parts are rotated at odd angles (like
30 degrees, or whatever), then this won't quite work, but it should get you
started.

Dave, I tried your method in Excel and it appears to work with some caveats,
though I don't really understand the column mappings:

For left-to-right, you said to use columns D and G--that's corresponding to the
Y position and the B rotation parameter.  Shouldn't that be the X position and C
parameter?

You know, I think you're correct about that.  I think I'm the last person who
still uses LEdit as his primary LDraw platform, and for reasons of my own I
always orient my parts and models rotated 90 degrees relative to the true LDraw
standard orientation.

Maybe I should give a specific example of the default orientation, with the 2x4
brick at cursor position x=100, y=0, and z=-10.  The letters correspond to the
Excel columns:

A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P

    1   16  100 0  -10  1   0   0   0   1   0   0   0   1   3001.DAT

The mirrored left-to-right, the line would read this way:

A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P

    1   16  100 0  -10 -1   0   0   0   1   0   0   0  -1   3001.DAT

Dumb, dumb, dumb.  To be a true "mirror" as you've requested, the second example
should have read this way:

A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P

     1   16 -100 0  -10 -1   0   0   0   1   0   0   0  -1   3001.DAT

The way I originally posted it, the 3001 brick would be flipped left-to-right,
but it would be at the same location as the non-flipped brick.

Sorry about that.

Dave!



Message has 1 Reply:
  Re: Quick way to mirror-image a model?
 
(...) Wouldn't that still be a 180 degree rotation rather than a flip, since -1 0 0 (x y z) * 0 1 0 = (-x y -z) 0 0 -1 ? Or am I laying out my rotation matrix incorrectly (is the first line a b c or a d g)? Sorry for all the stupid questions, I'm (...) (20 years ago, 18-Jun-04, to lugnet.cad)

Message is in Reply To:
  Re: Quick way to mirror-image a model?  [DAT]
 
(...) You know, I think you're correct about that. I think I'm the last person who still uses LEdit as his primary LDraw platform, and for reasons of my own I always orient my parts and models rotated 90 degrees relative to the true LDraw standard (...) (20 years ago, 17-Jun-04, to lugnet.cad)

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