is here some way to extract the edge of a 2D object as lines?
I got some time to go back to playing with using Open-/Python-SCAD to pass
colored SVG (where the color contains conveys information about
cutting/engraving/scoring/etc.)...
The thing I am stuck on is that I have a 2D model, or use
3D_object.project(cut=true), but I have not figured out how to convert the
edge of the 2D polygon to lines? How is this done?
Thanks in advance.
EBo --
I have found a number of places that define line() as a 2D or 3D objects <
https://openhome.cc/eGossip/OpenSCAD/Polyline.html>, which build a line
(with its width) as polygons. Is there no actual line primitive in
OpenSCAD?
On Thu, Feb 5, 2026 at 10:29 PM John David ebo.2112@gmail.com wrote:
I got some time to go back to playing with using Open-/Python-SCAD to pass
colored SVG (where the color contains conveys information about
cutting/engraving/scoring/etc.)...
The thing I am stuck on is that I have a 2D model, or use
3D_object.project(cut=true), but I have not figured out how to convert the
edge of the 2D polygon to lines? How is this done?
Thanks in advance.
EBo --
On 2/5/2026 7:46 PM, John David via Discuss wrote:
I have found a number of places that define line() as a 2D or 3D
objects https://openhome.cc/eGossip/OpenSCAD/Polyline.html, which
build a line (with its width) as polygons. Is there no actual line
primitive in OpenSCAD?
There is no actual line primitive in OpenSCAD. OpenSCAD deals with
solid 3D polyhedra and filled 2D polygons, and does not deal with any
other variations (e.g. points, lines, unfilled objects).
OEP7: Mixed Dimension Geometry Support
https://github.com/openscad/openscad/wiki/OEP7:-Mixed-Dimension-Geometry-Support
discusses some ideas for supporting additional variations, but I am not
aware of any current effort in that area.
On 2/5/2026 8:59 PM, Jordan Brown via Discuss wrote:
There is no actual line primitive in OpenSCAD. OpenSCAD deals with
solid 3D polyhedra and filled 2D polygons, and does not deal with any
other variations (e.g. points, lines, unfilled objects).
I should add a small disclaimer to that. There are a few cases that are
not exactly 3D polyhedra and not exactly 2D polygons, that sort of work,
some of the time:
- 2D polygons transformed out of the Z=0 plane will be previewed
sensibly, but will render and extrude projected at Z=0. - You can give hull() a "polyhedron" that consists of a point cloud,
and it'll give you a hull of those points. (I don't recall whether
you have to pretend to group them into faces, but you don't have to
group them into sensible faces.) - You can create "incomplete" polyhedra, where the faces aren't fully
and correctly connected. Previewing will more or less work.
Rendering will fail as soon as it tries to do any boolean
operation. (This is actually quite useful while you are
constructing and debugging a polyhedron.)
But there's definitely no lines or points.
Thank you, Jordan, I was afraid of that. There are a couple of us who have
been trying to generate colored SVG images to export into laser cutters and
the like. I have colored SVG now working, but by using diffs of objects
with offsets, I end up getting 2x lines (which would force the laser to go
over the path twice... I'm now looking at the experimental gcode support
and see where that takes me.
Thanks again, and not having point or line primitives explains a lot of
confusion I have been having.
On Fri, Feb 6, 2026 at 12:06 AM Jordan Brown openscad@jordan.maileater.net
wrote:
On 2/5/2026 8:59 PM, Jordan Brown via Discuss wrote:
There is no actual line primitive in OpenSCAD. OpenSCAD deals with solid
3D polyhedra and filled 2D polygons, and does not deal with any other
variations (e.g. points, lines, unfilled objects).
I should add a small disclaimer to that. There are a few cases that are
not exactly 3D polyhedra and not exactly 2D polygons, that sort of work,
some of the time:
- 2D polygons transformed out of the Z=0 plane will be previewed
sensibly, but will render and extrude projected at Z=0.
- You can give hull() a "polyhedron" that consists of a point cloud,
and it'll give you a hull of those points. (I don't recall whether you
have to pretend to group them into faces, but you don't have to group them
into *sensible* faces.)
- You can create "incomplete" polyhedra, where the faces aren't fully
and correctly connected. Previewing will more or less work. Rendering
will fail as soon as it tries to do any boolean operation. (This is
actually quite useful while you are constructing and debugging a
polyhedron.)
But there's definitely no lines or points.
A few lines of code will do what you want wrt coloured lines in openscad.
module line(p1,p2,t,col){
color(col)hull(){
translate(p1)circle(d=t);
translate(p2)circle(d=t);
}
};
line([0,20],[5,9],0.5,"red");
On 06/02/2026 06:06, John David via Discuss wrote:
Thank you, Jordan, I was afraid of that. There are a couple of us who
have been trying to generate colored SVG images to export into laser
cutters and the like. I have colored SVG now working, but by using
diffs of objects with offsets, I end up getting 2x lines (which would
force the laser to go over the path twice... I'm now looking at the
experimental gcode support and see where that takes me.
Thanks again, and not having point or line primitives explains a lot
of confusion I have been having.
On Fri, Feb 6, 2026 at 12:06 AM Jordan Brown
openscad@jordan.maileater.net wrote:
On 2/5/2026 8:59 PM, Jordan Brown via Discuss wrote:
There is no actual line primitive in OpenSCAD. OpenSCAD deals
with solid 3D polyhedra and filled 2D polygons, and does not deal
with any other variations (e.g. points, lines, unfilled objects).
I should add a small disclaimer to that. There are a few cases
that are not exactly 3D polyhedra and not exactly 2D polygons,
that sort of work, some of the time:
* 2D polygons transformed out of the Z=0 plane will be previewed
sensibly, but will render and extrude projected at Z=0.
* You can give hull() a "polyhedron" that consists of a point
cloud, and it'll give you a hull of those points. (I don't
recall whether you have to pretend to group them into faces,
but you don't have to group them into *sensible* faces.)
* You can create "incomplete" polyhedra, where the faces aren't
fully and correctly connected. Previewing will more or less
work. Rendering will fail as soon as it tries to do any
boolean operation. (This is actually quite useful while you
are constructing and debugging a polyhedron.)
But there's definitely no lines or points.
OpenSCAD mailing list
To unsubscribe send an email todiscuss-leave@lists.openscad.org
Raymond, your lines are actually 2D because they have a width and therefore
suitable for visualization.
(and its needs a moderate amount of processingm circle, hull)
I wished, OpenSCAD would also start to support real 1D elements.
Effectively its just one additional data type
More datatypes don make sense.
On Fri, Feb 6, 2026 at 11:25 AM Raymond West via Discuss <
discuss@lists.openscad.org> wrote:
A few lines of code will do what you want wrt coloured lines in openscad.
module line(p1,p2,t,col){
color(col)hull(){
translate(p1)circle(d=t);
translate(p2)circle(d=t);
}
};
line([0,20],[5,9],0.5,"red");
On 06/02/2026 06:06, John David via Discuss wrote:
Thank you, Jordan, I was afraid of that. There are a couple of us who have
been trying to generate colored SVG images to export into laser cutters and
the like. I have colored SVG now working, but by using diffs of objects
with offsets, I end up getting 2x lines (which would force the laser to go
over the path twice... I'm now looking at the experimental gcode support
and see where that takes me.
Thanks again, and not having point or line primitives explains a lot of
confusion I have been having.
On Fri, Feb 6, 2026 at 12:06 AM Jordan Brown <
openscad@jordan.maileater.net> wrote:
On 2/5/2026 8:59 PM, Jordan Brown via Discuss wrote:
There is no actual line primitive in OpenSCAD. OpenSCAD deals with solid
3D polyhedra and filled 2D polygons, and does not deal with any other
variations (e.g. points, lines, unfilled objects).
I should add a small disclaimer to that. There are a few cases that are
not exactly 3D polyhedra and not exactly 2D polygons, that sort of work,
some of the time:
- 2D polygons transformed out of the Z=0 plane will be previewed
sensibly, but will render and extrude projected at Z=0.
- You can give hull() a "polyhedron" that consists of a point cloud,
and it'll give you a hull of those points. (I don't recall whether you
have to pretend to group them into faces, but you don't have to group them
into *sensible* faces.)
- You can create "incomplete" polyhedra, where the faces aren't fully
and correctly connected. Previewing will more or less work. Rendering
will fail as soon as it tries to do any boolean operation. (This is
actually quite useful while you are constructing and debugging a
polyhedron.)
But there's definitely no lines or points.
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
Or perhaps use a python script to remove the fill parameter from the SVG
polygons
On Fri, 6 Feb 2026, 10:25 Raymond West via Discuss, <
discuss@lists.openscad.org> wrote:
A few lines of code will do what you want wrt coloured lines in openscad.
module line(p1,p2,t,col){
color(col)hull(){
translate(p1)circle(d=t);
translate(p2)circle(d=t);
}
};
line([0,20],[5,9],0.5,"red");
On 06/02/2026 06:06, John David via Discuss wrote:
Thank you, Jordan, I was afraid of that. There are a couple of us who have
been trying to generate colored SVG images to export into laser cutters and
the like. I have colored SVG now working, but by using diffs of objects
with offsets, I end up getting 2x lines (which would force the laser to go
over the path twice... I'm now looking at the experimental gcode support
and see where that takes me.
Thanks again, and not having point or line primitives explains a lot of
confusion I have been having.
On Fri, Feb 6, 2026 at 12:06 AM Jordan Brown <
openscad@jordan.maileater.net> wrote:
On 2/5/2026 8:59 PM, Jordan Brown via Discuss wrote:
There is no actual line primitive in OpenSCAD. OpenSCAD deals with solid
3D polyhedra and filled 2D polygons, and does not deal with any other
variations (e.g. points, lines, unfilled objects).
I should add a small disclaimer to that. There are a few cases that are
not exactly 3D polyhedra and not exactly 2D polygons, that sort of work,
some of the time:
- 2D polygons transformed out of the Z=0 plane will be previewed
sensibly, but will render and extrude projected at Z=0.
- You can give hull() a "polyhedron" that consists of a point cloud,
and it'll give you a hull of those points. (I don't recall whether you
have to pretend to group them into faces, but you don't have to group them
into *sensible* faces.)
- You can create "incomplete" polyhedra, where the faces aren't fully
and correctly connected. Previewing will more or less work. Rendering
will fail as soon as it tries to do any boolean operation. (This is
actually quite useful while you are constructing and debugging a
polyhedron.)
But there's definitely no lines or points.
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
John David wrote:
I got some time to go back to playing with using Open-/Python-SCAD to pass
colored SVG (where the color contains conveys information about
cutting/engraving/scoring/etc.)...
The thing I am stuck on is that I have a 2D model, or use
3D_object.project(cut=true), but I have not figured out how to convert the
edge of the 2D polygon to lines? How is this done?
Thanks in advance.
EBo --
It can be done like this:
module xy() then colour1 offset(+off) xy(); followed by colour2 offset(-off) xyz();
where xy is a 2D shape and off stands for offset, if you can live with a crude workaround.
See also:
https://lists.openscad.org/empathy/thread/6SDAM4WFVBADFAOTZ2I3EFSEDN7UREZ4
https://lists.openscad.org/empathy/thread/TU7WPMWZLVJMXDK2RCFHJ2A7GKJGZUUG
https://lists.openscad.org/empathy/thread/VJFEXUE5NFU4J7GHIX3LGCYLOHLZRJ4E
The reply was wrt coloured simulated laser cutter lines. What other
lines are there? Ones defining edges? point to point? Here is some code,
for lines you can not visualise.
On 06/02/2026 10:50, Guenther Sohler via Discuss wrote:
Raymond, your lines are actually 2D because they have a width and
therefore suitable for visualization.
(and its needs a moderate amount of processingm circle, hull)
I wished, OpenSCAD would also start to support real 1D elements.
Effectively its just one additional data type
More datatypes don make sense.
On Fri, Feb 6, 2026 at 11:25 AM Raymond West via Discuss
discuss@lists.openscad.org wrote:
A few lines of code will do what you want wrt coloured lines in
openscad.
module line(p1,p2,t,col){
color(col)hull(){
translate(p1)circle(d=t);
translate(p2)circle(d=t);
}
};
line([0,20],[5,9],0.5,"red");
On 06/02/2026 06:06, John David via Discuss wrote:
Thank you, Jordan, I was afraid of that. There are a couple of us
who have been trying to generate colored SVG images to export
into laser cutters and the like. I have colored SVG now working,
but by using diffs of objects with offsets, I end up getting 2x
lines (which would force the laser to go over the path twice...
I'm now looking at the experimental gcode support and see where
that takes me.
Thanks again, and not having point or line primitives explains a
lot of confusion I have been having.
On Fri, Feb 6, 2026 at 12:06 AM Jordan Brown
<openscad@jordan.maileater.net> wrote:
On 2/5/2026 8:59 PM, Jordan Brown via Discuss wrote:
There is no actual line primitive in OpenSCAD. OpenSCAD
deals with solid 3D polyhedra and filled 2D polygons, and
does not deal with any other variations (e.g. points, lines,
unfilled objects).
I should add a small disclaimer to that. There are a few
cases that are not exactly 3D polyhedra and not exactly 2D
polygons, that sort of work, some of the time:
* 2D polygons transformed out of the Z=0 plane will be
previewed sensibly, but will render and extrude projected
at Z=0.
* You can give hull() a "polyhedron" that consists of a
point cloud, and it'll give you a hull of those points.
(I don't recall whether you have to pretend to group them
into faces, but you don't have to group them into
*sensible* faces.)
* You can create "incomplete" polyhedra, where the faces
aren't fully and correctly connected. Previewing will
more or less work. Rendering will fail as soon as it
tries to do any boolean operation. (This is actually
quite useful while you are constructing and debugging a
polyhedron.)
But there's definitely no lines or points.
_______________________________________________
OpenSCAD mailing list
To unsubscribe send an email todiscuss-leave@lists.openscad.org
_______________________________________________
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
OpenSCAD mailing list
To unsubscribe send an email todiscuss-leave@lists.openscad.org