Source Code

Source code can be found at: https://github.com/utlco/tcnc

git clone https://github.com/utlco/tcnc.git

Modules

• Inkscape extensions
  • Tcnc
  • Quasink
  • Voronoi
  • Polypath
  • Polysmooth
  • Sinewave
• inkscape - Inkscape extension package
  • inkscape.inkext
  • inkscape.inksvg
• svg - SVG drawing/utility package
  • svg.svg
  • svg.css
  • svg.geomsvg
• geom - Basic 2D geometry package
  • geom.const
  • geom.transform2d
  • geom.point
  • geom.line
  • geom.arc
  • geom.ellipse
  • geom.bezier
  • geom.box
  • geom.polygon
  • geom.planargraph
  • geom.voronoi
  • geom.voronoiclip
  • geom.quasi
  • geom.fillet
  • geom.util
  • geom.debug
• cam - CAM/GCode package
  • cam
  • cam.gcode
  • cam.simplecam
  • cam.toolpath
  • cam.util
  • cam.fillet
  • cam.offset

• Module Index

Notes

While performance is important, maintainability and clarity has been more of a priority.

My memory is too unreliable to understand some opaque code I wrote two months ago, so I’ve tried to mitigate this somewhat with comments and avoiding magical python.

Why

You may be wondering why I didn’t just use or extend gcodetools, which is currently packaged with Inkscape. Well, to be honest I found the author’s code difficult to follow and it was very time consuming to customize for my needs. I had a hard time understanding the author’s biarc curve approximation algorithm so I went to primary sources and wrote my own version that works pretty well (maybe even a bit better).

Like any programmer I’ve a mild case of NIH syndrome and I also just wanted code that I understood well and could modify easily and quickly for project-specific requirements.

Lots of people use gcodetools and it has many more features (such as pocketing and raster fills). I highly recommend checking it out.

Unit handling

Unit handling in SVG and Inkscape can be confusing.

The problem mainly stems from SVG’s viewbox/viewport handling and Inkscape’s concept of a ‘document unit’. In addition, the SVG viewbox attribute can specify a box with a different aspect ratio than its parent - which is really only relevant in web browser contexts. Inkscape calls document units ‘default units’ in the UI, which further confuses things. Weirdly, the default document unit is pixels even when using a document template specified in inches or mm.

Anyway, for the purposes of using tcnc as an Inkscape extension, the simplest way to deal with this is in File->Document Properties…, set the ‘default units’ to the same value as the units used to specify the document size, and to use either inches or mm for both.

Inkscape extensions

If you are wondering how to build an Inkscape extension then it might be helpful to look at this source code. There are some reusable components as well that make writing extensions a little easier.

I suggest also taking a look at clearly written and well documented extensions such as the Eggbot extension. Documentation about Inkscape extensions is fairly poor and the best way to learn how to write one is to look at previous attempts.

Reusable packages

There are also some handy libraries, such as the SVG and geometry packages, that are more generally useful. I rewrote the Inkscape extension classes partly because Inkscape version .91 broke my extensions (mainly because of unit handling) and I just wanted to hoist more of the biolerplate involved with writing extensions.

I added a docunits option checker to convert UI values to current document units automatically. The creation of a debug layer and logging output file is done by the extension base class as well.

If you find any of this useful, great!

Etc.

I’ve been slowly converting doc strings to the Google python style since it’s more readable than the standard reST style. There’s currently a mix of the two styles… Sphinx handles both just fine.

Testing has been artisinal.

Most modules produce some pylint warnings. But IMO pylint is overly nit-picky about some things.

An attempt has been made to start migrating the code to full python3 compatibility, but this has not been tested. Inkscape still depends on Python 2.6+…

Emails, pull requests, feature requests, and issues are infrequently examined and may be left ignored for an uncomfortably long period of time… Sorry about that. Bug reports are welcome in any case.