Juicy-gcode: A Haskell SVG to GCode converter

Synopsis

Haskell SVG to G-code converter that aims to support most SVG features. The flavor of the generated G-Code can be influenced providing a configuration file.

Installation and usage

The easiest way is to download one of the pre-built binaries from the releases page. Alternatively, you can build from source code as follows:

• Install Stack if you do not have it yet
• $ git clone https://github.com/domoszlai/juicy-gcode.git
• $ stack build
• $ stack install
• $ juicy-gcode --help

juicy-gcode - The SVG to G-Code converter

Usage: juicy-gcode.exe SVGFILE [-f|--flavor CONFIGFILE] [-o|--output OUTPUTFILE]
                       [-d|--dpi DPI]
  Convert SVGFILE to G-Code

Available options:
  -h,--help                Show this help text
  SVGFILE                  The SVG file to be converted
  -f,--flavor CONFIGFILE   Configuration of G-Code flavor
  -o,--output OUTPUTFILE   The output G-Code file (default is standard output)
  -d,--dpi DPI             Density of the SVG file (default is 72 DPI)

Configuration

The default G-Code flavor configuration file is the following:

gcode
{
   begin = "G17;G90;G0 Z10;G0 X0 Y0;M3;G4 P2000.000000"
   end = "G0 Z10;M5;M2" 
   toolon =  "G00 Z10"
   tooloff = "G01 Z0 F10.00"
}

A new configuration file can be set by the --flavor or -f command line option.

Another configurable property is the resolution of the SVG image in DPI (dot per inch). It can be given by the --dpi or -d command line option. Default value is 72 DPI.

Limitations

Missing features:

• text (easy with e.g. FontyFruity, maybe once, you can convert text to curves easily anyway)
• filling (moderately difficult)
• clipping (probably not easy, maybe once)
• images (not planned)

Testing and bugs

There is a JavaScript hanging plotter simulator mainly developed to test the generated gcode. Please file an issue if you run into a problem (or drop me an email to dlacko @ gmail.com).

Implementation

SVG images are built using the following shapes (all of these are subject of an arbitrary affine transformation):

• lines
• circles
• ellipses
• elliptic arcs with optional x axis rotation
• quadratic and cubic bezier curves

In contrast G-Code implements only

• lines
• non-elliptical arcs

That means that only lines, circles and some arcs (non-elliptic ones without rotation) can be transleted to G-Code directly. If transformations are also counted, then only lines can be translated to G-Code directly as circles are not invariant under affine transformations. Because of this, the converter is implemented in two stages.

Stage 1

All the SVG drawing operations are translated to a list of MoveTo, LineTo and CubicBezierTo operations as these are invariant under affine transformations. Arcs, circles and ellipses can be easily approximated with bezier curves with a small error.

Stage 2

Cubic bezier curves are approximated with Biarcs using the algorithm described in [1] and explained here.