Polyline Converter

Convert a polyline (a series of points) from one format to another.

Three formats are currently supported:

• Rectangular (XY graphing coordinates)
• "Theta-Rho" notation used by Sisyphus Tables
• G-Code

Important Note about Rectangular to Theta-Rho Conversion

When converting from the x/y position of rectangular coordinates to the angle/radius position of polar/Theta-Rho coordinates it is important to remember that a straight line between two rectangular points will not be a straight line in polar coordinates. In order to build a straight line in THR coordinates, the rectangular coordinates must first be subdivided into smaller line segments to minimize the arcing effect of THR point-to-point segments. This is handled in this code by passing a second "max_segment_length" parameter to ThetaRho.convert().

Installation

npm install @markroland/polyline-converter

Command Line Usage

node ./index.js [input filepath.gcode|rect|thr] [gcode|rect|thr]

Tip, if npm link has been used you can use:

convert-polyline [input filepath.gcode|rect|thr] [gcode|rect|thr]

Examples

Convert Theta-Rho to Rectangular

node ./index.js rectangle.csv thr

Save Directly to a File

node ./index.js rectangle.csv thr > rectangle.thr

Formats

Theta Rho

Theta-Rho format should have a angular theta value in radians followed by a space followed by a radius/rho value ranging between zero and one.

The center of the drawing area is represented as 0 0.

The scale for theta-rho units is such that a Rho value of 1 is the maximum radius for the drawing area.

3.14 0.5

Rectangular

The Rectangular follows standard X-Y graphing coordinates. An "x" values should be followed by a comma, followed by a "y" value.

The center of the drawing area is represented as 0,0. Positive "x" is directed to the right and positive "y" is directed to the top.

The scale for rectangular units can be interpreted by the destination. This could be pixels, millimeters, inches or anything really.

-100.0,120.0

G-Code

The G-Code line format should start with a "G0" command, followed by "X" and then an numeric value, followed by a space, followed by "Y", followed by a numeric value.

The origin point of G-Code, X0 Y0, is traditionally located in the bottom-left of the drawing area. Therefore all values should be positive. The center of the drawing area would be represented as halfway between zero and the drawing extent of the plotting device in each direction.

The units for the G-Code should be specified in a preamble to the coordinates. Use G20 to specify inches or G21 for millimeters.

G0 X100.0 Y100.0

In any format, any line staring with a pound sign (#) will be interpreted as a comment that should be ignored.

License

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.