rotate_extrude Problem

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rotate_extrude Problem

BruceXling
I am trying to follow the Extruding a Polygon example in the OpenSCAD User
Manual.  I am getting a Preview result as shown in the attached photo.  The
Preview seems to have inherited the nominal 1 unit thickness of the polygon
shape.  When I progress to the Render function I get the following warnings:

Rendering Polygon Mesh using CGAL...
WARNING: Mixing 2D and 3D objects is not supported.
WARNING: Ignoring 3D child object for 2D operation

At the conclusion of the Render process the graphic displays just a 1
Dimensional red line on the x-axis.

Any idea what I am doing wrong here?



<http://forum.openscad.org/file/t2070/Rotate_Extrude.jpg>



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Re: rotate_extrude Problem

Greg Frost
Without seeing your code it is hard to tell exactly what the problem might be however I have had problems in the past attempting to rotate extrude A 2-D shape that spans both sides of the y-axis. When doing rotate extrudes, you should just draw half of the object and it should be all in positive X space. Otherwise you end up with a double shelled object which causes problems down the line.

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> On 11 Nov 2017, at 10:24 am, BruceXling <[hidden email]> wrote:
>
> I am trying to follow the Extruding a Polygon example in the OpenSCAD User
> Manual.  I am getting a Preview result as shown in the attached photo.  The
> Preview seems to have inherited the nominal 1 unit thickness of the polygon
> shape.  When I progress to the Render function I get the following warnings:
>
> Rendering Polygon Mesh using CGAL...
> WARNING: Mixing 2D and 3D objects is not supported.
> WARNING: Ignoring 3D child object for 2D operation
>
> At the conclusion of the Render process the graphic displays just a 1
> Dimensional red line on the x-axis.
>
> Any idea what I am doing wrong here?
>
>
>
> <http://forum.openscad.org/file/t2070/Rotate_Extrude.jpg>
>
>
>
> --
> Sent from: http://forum.openscad.org/
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> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

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Re: rotate_extrude Problem

BruceXling
Many thanks Greg_Frost for your thoughts on my problem.  The code is lifted
straight out of the User Manual and I’ll repeat here:

rotate([90,0,0])        polygon(
points=[[0,0],[2,1],[1,2],[1,3],[3,4],[0,5]] );
rotate_extrude($fn=200) polygon(
points=[[0,0],[2,1],[1,2],[1,3],[3,4],[0,5]] );

Now that I understand that these two lines are a 2D function followed by a
3D function everything makes sense.  If I execute just the second line
everything works as I would expect.

That should teach me to actually read what I copy and paste, but it probably
won’t.



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Re: rotate_extrude Problem

Ronaldo
In reply to this post by BruceXling
You can't render (F6) a mix of 2D and 3D objects as the error message says. Try render just the polygon or just the rotate extrusion. The preview of polygons may be misleading in OpenSCAD. First, polygons are previewed with a thickness that they really don't have. Besides, transformations of 2D objects, like the rotation of your code, that take the objects away from the xy plane are differently represented by preview and render. So, avoid this kind of transformations for your mental health.

2017-11-10 21:54 GMT-02:00 BruceXling <[hidden email]>:
I am trying to follow the Extruding a Polygon example in the OpenSCAD User
Manual.  I am getting a Preview result as shown in the attached photo.  The
Preview seems to have inherited the nominal 1 unit thickness of the polygon
shape.  When I progress to the Render function I get the following warnings:

Rendering Polygon Mesh using CGAL...
WARNING: Mixing 2D and 3D objects is not supported.
WARNING: Ignoring 3D child object for 2D operation

At the conclusion of the Render process the graphic displays just a 1
Dimensional red line on the x-axis.

Any idea what I am doing wrong here?



<http://forum.openscad.org/file/t2070/Rotate_Extrude.jpg>




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