polygon-crosshatching

Fill a convex polygon with crosshatching defined by a particular spacing and at a particular angle. This is a umd build so it can be included in the browser or in your node app.

Usage

polygonCrosshatching(polygon, angle, start_density, [end_density, [redistribution_function]])

polygon {Point List} The convex polygon in which the crosshatching will be placed
angle {Number} The angle that the crosshatching is created in radians
start_density {Number > 0} The starting spacing density of the crosshatching
end_density {Number > 0} The ending spacing density of the crosshatching
redistribution_function {function(number)} The redistribution function is an argument that lets you change the behavior of the crosshatching within the polygon. The function takes a number from 0-1 and returns a number from 0-1. The default function in the linear or identity function (x => x)

The polygon input is a polygon in a list of all the verticies

[
  [x1, y1], // Vertex 1
  [x2, y2], // Vertex 2
  [x3, y3], // Vertex 3
  ...
  [xn, yn] // Last Vertex
]

The output is a list of line with the points in list form

[
  [[x1, y1], [x2, y2]], // one line
  [[x1, y1], [x2, y2]], // another
  ...
]

Example in code

// Browser include
<script src="./node_modules/polygon-crosshatching/build.js"></script>
// this incldues the global function `polygonCrosshatching` into the namespace

// Node's CJS Include
const poylgonCrosshatching = require('polygon-crosshatching');

const polygon = [
  [   0,   0 ],
  [ 100,   0 ],
  [ 120, 100 ],
  [  50, 200 ],
  [  20, 100 ]
];
const spacing = 5;
const angle = Math.PI / 3; // 30deg

const hatches = polygonCrosshatching(polygon, angle, spacing);
// output is a list of lines

const ending_spacing = 50;

// To create a gradient from the starting angle to the ending angle within the polygon
const gradient_hatching = polygonCrosshatching(polygon, angle, spacing, ending_spacing);

// Create the crosshatching with a redistribution function
const squared = x => x*x;
const redistributed_hatching = polygonCrosshatching(polygon, angle, spacing, ending_spacing, squared);

Example Uniform Spacing

Example Gradient

Example Sinusoidal Redistribution Function

Change Log

Version 1.3.0

Fixed a bug in the UMV build with the lack of the lerp function.

Version 1.2.0

Added support for changing the gradient distribution. This changes how the lines are spaced within the the polygon.

Version 1.1.0

Added in the gradient crosshatching and changed the arrangement of the arguments in the function from (polygon, spacing, angle) to (polygon, angle, spacing_start, spacing_end) for better consistency and extensability.

Evelios/polygon-crosshatching