Subject:
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Re: Quick way to mirror-image a model?
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Newsgroups:
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lugnet.cad
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Date:
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Thu, 17 Jun 2004 15:20:23 GMT
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Viewed:
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1794 times
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In lugnet.cad, Dave Schuler wrote:
> In lugnet.cad, Steve Krass wrote:
> > In lugnet.cad, Carl Nelson wrote:
> > > Does anybody know a quick way to do a mirror image of an LDraw
> > > model? For example, a castle that I'm working on has a left and
> > > right tower that are mirror images (not rotations) of each other
> > > (and the rear corner towers are mirrors of the front ones).
> > > Rather than make 4 different models, is there a quick way to flip
> > > my model into the four different towers?
> >
> > I usually use submodels save your tower as a tower-left or
> > something. you have to go thruogh each part and change either the
> > x or z value to the opposite value (ex. if the X is -300 change to
> > 300) then rotate each part 180 degrees. There are also a lot of
> > left and right parts which need to be swaped.
> >
> > or in povray you can use scale with a negative value
> > (ex. scale<-1,0,0> ) this will mirror around the x axis.
> >
> > There is no easy way.
>
> The way I usually do this is clunky, but it basically works. It
> also requires a little familiarity with MS Excel and some kind of
> text editor, as well as an understanding of the LDraw DAT-file
> format.
>
> Create a backup of the MOC file. Open the backup file in MS Excel,
> in "space delimited" format. For simplicity, let's assume the
> following:
>
> 1. Any title info within the DAT file is omitted for this operation
> 2. The ZERO character in line one at the start of the file appears in
> cell A1 in the Excel spreadsheet
> 3. The first linetype 1 statement begins in cell B2 in the Excel
> spreadsheet
>
> Here's how I do what I do when I do it:
>
> 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.
>
> 1. Identify which lines contain the parts of the model that you
> want to mirror (let's say lines 2 through 50).
> 2. Copy these lines to another location in the file (let's say 51
> through 99)
> 3. Set cell D51 to equal "-D2"
> 4. Select cell D51 and "copy"
> 5. Select cells D52 through D99
> 6. Paste
>
> At this point the parts now exist in their original locations and at
> the corresponding mirrored locations, but the mirrored locations are
> not oriented correctly. To correct the orientation, do the
> following:
>
> 1. Select cell D51 and "copy"
> 2. Select cells G51 through G99
> 3. Paste
>
> This will invert the orientation left-to-right and vice versa.
>
> To perform the same mirroring front-to-back, perform the same steps
> as above, but instead of using columns D and G, you'd use columns F
> and O, respectively.
>
> To perform the same mirroring up-to-down, perform the same steps as
> above, but instead of using columns D and G, you'd use columns E and
> K, respectively.
>
> After you have made all of your changes, save the Excel spreadsheet
> in tab-delimited format, and use the .DAT extension in the file
> name, such as "MOC1.dat" • L
> At this point, the body of the MOC1.dat file has a bunch of tab
> characters where there should be spaces. Open the MOC1.dat file in
> a text-based editor that allows you to do bulk find-replace
> operations, and replace each of the "tab" characters with a single
> space.
>
> Save the file and open it in your LDraw platform of choice to view
> the results.
>
> Here's a Known Shortcoming of this method: it doesn't automatically
> accommodate linetype zero statements that appear within the body of
> the DAT file, nor does it automatically accommodate METASTATEMENTS.
> You'll need to tweak those manually if they present a problem.
>
> I apologize if my explanation is unclear, but I can attest to the
> effectiveness of the method, because I've used it dozens of times
> for model files and for new partfiles. Let me know if you'd like
> clarification on any point.
This is silly. Just put the structure you want to mirror in a
subfile and do this.
1 0 0 0 0 1 0 0 0 1 0 0 0 1 subfile.ldr
1 0 320 0 0 -1 0 0 0 1 0 0 0 1 subfile.ldr
You can do it in ldglite using the scale by (-1,1,1) command (just
like in POV). Then use your favorite CAD program to position the part
and it's mirror wherever you want them. If you like, inline them
both. That'll generate pictures that look correct. The only problem
will be if you use the LDR file to generate an inventory list and you
have distinct left and right parts like wing plates.
Don
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Message has 2 Replies:
 | | Re: Quick way to mirror-image a model?
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| (...) Won't that cause all of the LEGO logo on all of the studs in the mirrored parts to be reversed? I thought that part of the point of the question was to avoid that. I think that measures are being taken to correct the mirrored-logo issue, but (...) (20 years ago, 17-Jun-04, to lugnet.cad)
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Message is in Reply To:
| | Re: Quick way to mirror-image a model?
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| (...) The way I usually do this is clunky, but it basically works. It also requires a little familiarity with MS Excel and some kind of text editor, as well as an understanding of the LDraw DAT-file format. Create a backup of the MOC file. Open the (...) (20 years ago, 17-Jun-04, to lugnet.cad)
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