OpenSCAD::Polygons

You can create customized polygons in OpenSCAD by specifying points and paths. The path is either a single vector, enumerating the points in a list and the order to traverse the points, or, a vector of vectors, ie a list of point lists for each seperate curve of the polygon. You would need to use a vector of vectors if your polygon has holes. The parameter is optional and if you omit it OpenSCAD assumes that the points are in order. syntax:

polygon(points = [ [x, y], ... ], paths = [ [p1, p2, p3..], ...], convexity = N);

example:

polygon(points=[[0,0],[100,0],[0,100],[10,10],[80,10],[10,80]], paths=[[0,1,2],[3,4,5]]);

In this example, you have 6 points (three for the "outer" triangle, and three for the "inner" one). The points (the numbers that correspond to the position of a point defined in the points vector) are connected using 2 paths.

In order to get a 3D object, you either extrude a 2D polygon (linear or (rotation ) or directly use the polyhedron primitive solid. When using extrusion to form solids, its important to realize that the winding direction of the polygon is significant. If a polygon is wound in the wrong direction with respect to the axis of rotation, the final solid (after extrusion) may end up invisible. This problem can be checked for by flipping the polygon using scale([-1,1]) (assuming that extrusion is being done about the Z axis as it is by default).

Working with Polygons in OpenSCAD can get confusing, but there are some helper applications that can simplify the proces for you.

Click on the links below to explore each option:

Create your polygons in Inkscape or import svgs into Inkscape and export your shapes with an extension
Use OpenSCAD Polygon Generator

Inkscape and OpenSCAD extension

Download and install the latest version of eggbotcode
Download the src file for the inkscape-openscad-poly extension.
Copy the contents of the src directory to your Inkscape extensions/ directory. Typical locations for the extensions folders include:
- OS X - Applications:Inkscape.app:Contents:Resources/extensions
- Linux - /usr/share/inkscape/extensions
- Windows - C:\Program Files\Inkscape\share\extensions
Open Inkscape (www.inkscape.org — free, open-source vector based drawing program ) and create a new document (CTRL+N).
Under the file menu, go to Document Properties and change the default units in the upper right hand corner to millimeters (SHIFT+CTRL+D). This will change the rulers from pixels to millimeters.
Create a drawing
There should be square and round handles on the object, which indicates the drawing is an .svg object.
You need to convert the drawing object to a path. [Shift+Ctrl+C]
Select the node tool [N]. The handles on the object now look like gray squares. This indicates you have a path.
Select every node (CTRL+A), and click on Insert new nodes into selected segments.

Press a few times if you want a smoother object, but don't overdo it.
With all the nodes still selected, click on the straighten segments. The lines are straight, but due to the sheer numbers, you see a curve!
Select everything, then go to Document Properties [Shift+Ctrl+D] and click on Resize page to content:
Click on Resize page to drawing or selection.

Don't panic if your dots seem like they are outside the page, it will all be fine in the end.
Navigate to File>Save As (SHIFT+CTRL+S) and save the drawing.
You want to save the drawing as as OpenSCAD Polygons
Open the file in OpenSCAD

Before the module definition, include a call to linear_extrude: syntax:

linear_extrude(height=xx)
pathxxxx();

example:

linear_extrude(height=4){
	path3001();
}

Compile (F5)

Importing an SVG into Inkscape.

Find an svg file you'd like to use.

I'm downloading a kiwi bird from:clipartist
Open Inkscape
Navigate to File>Open (CTRL+O) and find your SVG
Under the file menu, go to Document Properties and change the default units in the upper right hand corner to millimeters (SHIFT+CTRL+D). This will change the rulers from pixels to millimeters.
Change the Fill to No Fill and set the stroke so that you can see the image:
You need to convert the drawing object to a path. [Shift+Ctrl+C]
Select the node tool [N]. The handles on the object now look like gray squares. This indicates you have a path.

Select every node (CTRL+A), click on Insert new nodes into selected segments.

Press a few times if you want a smoother object, but don't overdo it.
Set the segments to straight lines:
Select everything, then go to Document Properties [Shift+Ctrl+D] and click on Resize page to content:
Click on Resize page to drawing or selection.

Don't panic if your dots seem like they are outside the page, it will all be fine in the end.
Navigate to File>Save As (SHIFT+CTRL+S) and save the drawing.
You want to save the drawing as as OpenSCAD Polygons
Open the file in OpenSCAD

Before the module definition, include a call to linear_extrude: syntax:

linear_extrude(height=xx)
pathxxxx();

example:

linear_extrude(height=4){
	path3001();
}

Compile (F5)
Change the name of your module to something that makes sense:

OpenSCAD Polygon Generator

Inkscape and OpenSCAD extension

Importing an SVG into Inkscape.

Challenge: