2D mesh embedded in 3D -> 3D

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2D mesh embedded in 3D -> 3D

Kenneth Sloan
 
Begin forwarded message:

From: Kenneth Sloan <[hidden email]>
Subject: Re: [OpenSCAD] 2D mesh embedded in 3D -> 3D
Date: June 14, 2013 4:53:01 PM CDT
To: Alan Cox <[hidden email]>

Sorry - terminology clash.  I have a triangular mesh, with boundary.  It is not planar.  The one I'm working on now is shaped roughly like a railroad tunnel (think of those foam tunnels for model train sets.  The mesh describes the INSIDE surface of the tunnel.  It has various bumps and features, but is macroscopically similar to a half-pipe.  It is "2D" in the sense that it could be deformed to a disc - but it is NOT PLANAR and "projection" doesn't help.

So…the idea is to take this inside surface and offset it to produce the outside surface of the tunnel…and then (the easy part) stitch the two together to make the boundary of a solid.


-Kenneth Sloan



On Jun 14, 2013, at 4:45 PM, Alan Cox <[hidden email]> wrote:

GIVEN: an STL file describing a 2D mesh embedded in 3D.  Isomorphic to a disc, with a simple boundary.

If you have a 2D mesh projected thinly into 3D then you can use
projection() to get it back into 2D and linear_extrude to get it the size
you want ?

linear_extrude(...)
projection(...)
<rotate so in x/y plane>
import(...);

Alan



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Re: 2D mesh embedded in 3D -> 3D

nophead
Does openscad allow a non-manifold STL to be imported? If not then I can't see how you do it in openscad. If it does then previous discussion this evening suggest minkowski with a cube will make it manifold.


On 14 June 2013 22:55, Kenneth Sloan <[hidden email]> wrote:
 
Begin forwarded message:

From: Kenneth Sloan <[hidden email]>
Subject: Re: [OpenSCAD] 2D mesh embedded in 3D -> 3D
Date: June 14, 2013 4:53:01 PM CDT
To: Alan Cox <[hidden email]>

Sorry - terminology clash.  I have a triangular mesh, with boundary.  It is not planar.  The one I'm working on now is shaped roughly like a railroad tunnel (think of those foam tunnels for model train sets.  The mesh describes the INSIDE surface of the tunnel.  It has various bumps and features, but is macroscopically similar to a half-pipe.  It is "2D" in the sense that it could be deformed to a disc - but it is NOT PLANAR and "projection" doesn't help.

So…the idea is to take this inside surface and offset it to produce the outside surface of the tunnel…and then (the easy part) stitch the two together to make the boundary of a solid.


-Kenneth Sloan



On Jun 14, 2013, at 4:45 PM, Alan Cox <[hidden email]> wrote:

GIVEN: an STL file describing a 2D mesh embedded in 3D.  Isomorphic to a disc, with a simple boundary.

If you have a 2D mesh projected thinly into 3D then you can use
projection() to get it back into 2D and linear_extrude to get it the size
you want ?

linear_extrude(...)
projection(...)
<rotate so in x/y plane>
import(...);

Alan



_______________________________________________
OpenSCAD mailing list
[hidden email]
http://rocklinux.net/mailman/listinfo/openscad
http://openscad.org - https://flattr.com/thing/121566


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://rocklinux.net/mailman/listinfo/openscad
http://openscad.org - https://flattr.com/thing/121566