Turtle

A lightweight turtle graphics library for Clojure & ClojureScript. Includes renderers for SVG markup and bitmap images for Clojure, and a HTML5 canvas renderer for ClojureScript.

Examples

Clojure

(ns example1
  (:require
    [turtle.core :refer [draw!]]
    [turtle.renderer.bitmap :refer [->img]]))

(def triangle
  (take 12
    (cycle
      [:fwd 20, :right 120])))

(draw! ->img triangle [800 600])

Would return an AWT BufferedImage of size 800x600, with the triangle scaled to the full extent:

 #<BufferedImage BufferedImage@5d6b3f00: type = 1 DirectColorModel: rmask=ff0000 gmask=ff00 bmask=ff amask=0
 IntegerInterleavedRaster: width = 800 height = 600 #Bands = 3 xOff = 0 yOff = 0 dataOffset[0] 0>

This can then be rendered with javax.imageio.ImageIO into whatever graphics format.

The same triange rendered with the SVG renderer:

(ns example2
  (:require
    [turtle.core :refer [draw!]]
    [turtle.renderer.vector :refer [->svg]]))

(def triangle
  (take 12
    (cycle
      [:fwd 20, :right 120])))

(draw! ->svg triangle [800 600])

yields:

<svg height="600" overflow="visible" preserveAspectRatio="xMidYMid meet" version="1.0" width="800" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" zoomAndPan="magnify">
  <g transform="translate(100.0,500.0) scale(20.0,-20.0)">
    <path d="M0.0,0.0 L0.0,20.0 L17.32051,10.0 L0.0,0.0 " style="fill:none;stroke-width:3;stroke:red;"></path>
  </g>
</svg>

Pre-requisites

You will need Leiningen 2.7.1 or above installed.

Building

To build and install the library locally, run:

 lein cljsbuild once
 lein install

Including in your project

There is a version hosted at Clojars. For leiningen include a dependency:

[rm-hull/turtle "0.1.11"]

For maven-based projects, add the following to your pom.xml:

<dependency>
  <groupId>rm-hull</groupId>
  <artifactId>turtle</artifactId>
  <version>0.1.10</version>
</dependency>

TODO

• Documentation
• Examples
• Add tests & improve code coverage
• Investigate poor rendering quality on PNG renderer
• Implement commands:
  • :width n - set the stroke width
  • :fill - close the current path and fill with the selected color
• Perform rounding to 'n' decimal places

License

The MIT License (MIT)

Copyright (c) 2016 Richard Hull

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.