Mirroring models?

RE: Mirroring models?
#2
(2016-11-02, 5:39)Michael Horvath Wrote: Is there a tool I can use to mirror a model across an axis? I couldn't find such a command in MLCad.

Thanks.

Your question intrigued me, so I started playing around in Python to try to create a mirror of one of my recent 1300-part mpd files.  This turns out not to be a trivial exercise.

It's easy enough to mirror the location of the parts, but not so easy to mirror the rotation.  For any given mirroring, different parts will require different rotations to achieve perfect reflection.  And this inconsistency is independent of any rotation applied to the part within an assembly.

For example, take the simple case of a 1x12 Technic brick with a 2x2 corner plate on one end:

The assembly on the left has two pieces placed with no rotation about any axis.  The assembly on the right has the same two parts mirrored through the x=0 plane.  The Technic brick requires no rotation at all to be a true reflection, and will also be a reflection if rotated 180 degrees about the y-axis.  However, the 2x2 corner plate will only be a reflection if rotated about the y-axis 90 degrees counter-clockwise (or 270 degrees clockwise).  Clearly there is not a single rule that can be applied to these parts to achieve a perfect reflection of the assembly through the x=0 plane.

It was easy to write a simple program to do mirror parts with a basic (but frequently incorrect) assumption about rotation:  for reflections through the x=0 plane, reverse rotations about the y and z axes.  This gives a fairly good result, but it would still take some manual effort to clean up the resulting model into the final result you would be looking for.  I believe reflections through the y=0 and z=0 planes will be similar.

If you're interested, I'd be happy to provide my program or run your file through it myself to produce the first cut at a mirror that you can then edit yourself.

Kevin
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 Messages In This Thread Mirroring models? - by Michael Horvath - 2016-11-02, 5:39 RE: Mirroring models? - by Kevin - 2016-12-05, 12:00 RE: Mirroring models? - by Roland Melkert - 2016-12-06, 19:11 RE: Mirroring models? - by Don Heyse - 2016-12-25, 15:54

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