Offset polygon
This package implements algorithm of equidistant offset of polygon. It relies on the flatten-js library and its polygon model.
Algorithm based on the idea of morphological offset, when each edge of the polygon is mapped to its offset, and then boolean operation performed between original contour and offset edges. When offset value is positive, offset edges are unified with original contour, when negative - they are subtracted from original contour.
Contacts
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Installation
npm install --save @flatten-js/polygon-offsetThe package @flatten-js/core is peer dependency of this package and have to be installed separately:
npm install --save @flatten-js/coreUsage
import offset from "@flatten-js/polygon-offset"
let offsetPolygon = offset(polygon, offset_value)Example:
import {segment, point, Polygon} from "@flatten-js/core"
import offset from "@flatten-js/polygon-offset"
// Create polygon
let shapes = [
segment(point(200,100), point(200,300)),
segment(point(200,300), point(440,300)),
segment(point(440,300), point(300,200)),
segment(point(300,200), point(440,150)),
segment(point(440,150), point(500,150)),
segment(point(500,150), point(640,200)),
segment(point(640,200), point(500,300)),
segment(point(500,300), point(740,300)),
segment(point(740,300), point(740,100)),
segment(point(740,100), point(200,100))
];
let polygon = new Polygon();
polygon.addFace(shapes);
// Apply polygon offset
let offsetPolygon = offset(polygon, 20);