Twoville

Draft

Introduction

“Twoville is a programming language for generating two-dimensional SVG images that can be fed into vinyl or laser cutters. It also supports animation at the syntactic level.” (teaching machines, retrieved Jan 2019.

Twoville is under development (as of Jan 2020), but it can be used.

There exist few other alternatives, e.g. the no longer supported TurtleBlocks.

The language

Unlike the similar Madeup environment for 3D printing, created by the same author, this environment is as of Jan 2020 less well documented and does not include a block version.

The syntax looks a mix of Logo and JavaScript.

Example

Defining a blue rectangle

width = 150
height = 100
with rectangle ()
  corner = [0,0]
  size = [20, 10]
  color = [0.1, 0.1, 1]

Below, an alternative notation, using property syntax:

width = 150
height = 100
rect = rectangle ()
rect.corner = [0,0]
rect.size = [20, 10]
rect.color = [0.1, 0.1, 1]

Example

The following code defines a haircut

spokeDelta = 10
outerRadius = 50

with viewport
  center = [0, 0]
  size = [outerRadius * 2 + 10, outerRadius * 2 + 10]

// Spokes.
for i to 180+spokeDelta by spokeDelta
  degrees = i
  x = outerRadius * cos(degrees)
  y = outerRadius * sin(degrees)
  with line()
    vertex().position = [0, 0]
    vertex().position = [x, y]
    color = :black
    color = [0, 0, 0]
    size = 1

Spokes made with Twoville, inspired from PolarGraph

To make this suitable for laser cutting we can define a rectangle with a red hairline. Since rectangles do seem to require a fill color, we set its opacity to 0. The exported dimensions are pixels.

spokeDelta = 9
outerRadius = 100

with viewport
  center = [0, 0]
  size = [outerRadius * 2 + 10, outerRadius * 2 + 10]

// Spokes.
for i to 180+spokeDelta by spokeDelta
  degrees = i
  x = outerRadius * cos(degrees)
  y = outerRadius * sin(degrees)
  with line()
    vertex().position = [0, 0]
    vertex().position = [x, y]
    color = :black
    color = [0, 0, 0]
    size = 3

// rect for the cut line
with rectangle ()
  center = [0,outerRadius/2]
  size = [outerRadius*2+10,outerRadius+10]
  color = [0,0,0]
  opacity = 0
  stroke.size = 0.01
  stroke.color = [1.0,0.0,0.0]

Spokes made with Twoville, fit for laser cutting with a Trotec Speedy 100R

In order to laser cut this through Inkscape, we had to make two modifications to the export SVG drawing

• fix the document size, i.e. add some margin (File -> Document Properties)
• transform the spikes from lines to path (Path -> Stroke to Path)

Language elements

Like Madeup, Twoville supports conditionals, loops, functions, and arrays.

Primitive objects

common properties:

color = [R, G, B], values = 0..1 or :color
stroke.size
stroke.color
stroke.rgb
opacity = 0..1
rotate.pivot = [x,y]
rotate.degrees = deg

rectangle

rectangle ()

properties:

corner = [x,y]
center = [x,y]
size = [width, length]
rounding = x 

circle

circle ()

Properties

center
radius = [r]

path

path ()

properties

stroke.color = :blue
stoke.size = n.m
opacity = true or false
closed = true or false

arc

arc ()

Arcs are line segments of a circle. Must be used with path.

properties:

position = [x,y] defines what ??
degrees = db, defines the length of the arc

line

line ()

vertex().position = [x,y]

Animation

15 -> t means "time after 15 seconds"
t -> 30 means "time as it approaches 40 seconds"

Links

• https://twodee.org/twoville/, the online TwoVille environment.

• Introducing Twoville, February 24, 2018 by Chris Johnson. This piece explains some early animation features

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