Inkscape Optimize Path

An Inkscape extension that tries to make the longest continuous paths

It converts the paths to a graph, converts the graph to an Eulerian graph and finds an Eulerian cycle. It was written for the Axidraw pen plotter to reduce writing time of graph-like drawings like Voronoi diagrams and meshes.

Example result

Installation

• Copy the files optimizePaths.inx and optimizePaths.py in the Inkscape extension folder (On MacOS: /Applications/Inkscape.app/Contents/Resources/share/inkscape/extensions)
• Download the latest NetworkX package and copy the networkx folder in the Inkscape extension folder.
• Download the latest Decorator package and copy the decorator.py file in the Inkscape extension folder.

Usage

• Make sure to ungroup everything
• Make sure that the paths use only absolute coordinates (see trick below)
• Make sure to not have transforms on the paths. You can use the Apply Transform extension to remove them
• Select all the paths you want to optimize (currently only works with poly-lines)
• Open the extension (Extensions > Generate from Path > Optimize Path)
• Set the merge tolerance (0.1 should work in most cases)
• Choose the Overwrite rule:
  • "Allow" means that the result will be a single path which might (probably) will have some overlapping edges.
  • "Allow none" means that the results will be multiple disconnected paths but there will be no overlapping edges.
  • "Allow some" is an in-between, overlapping edges are allowed, but only in short numbers. This is probably the best choice in most cases.
• Press Apply

Trick to remove relative coordinates

1. Change the preferences for 'SVG Output > Path Data' to always use absolute coordinates. This will only affect newly created paths, or existing objects for which a rewrite of the path data is triggered.

2. For existing paths, use 'Edit > Select All in All Layers', and nudge the selection with the arrow keys (e.g. one step up and one back down again). This will trigger a rewrite of the path data in 'd' which will follow the changed preferences for optimized path data.

Dependencies NetworkX, a graph library, which depends on Decorator.