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clipPolygon

From-v3.2

Clips a polygon with a bounding box.

import {clipPolygon} from '@math.gl/polygon';

clipPolyline([-10, -10, 10, 10, 30, -10, -10, -10], [0, 0, 20, 20], {size: 2});
// returns [0, 0, 10, 10, 20, 0, 0, 0]

The clipping bounds are defined as an orthoganal rectangle on the XY plane. If a 3D polygon is supplied, it is clipped by the extuded volume from the bounding box.

Usage​

clipPolygon(positions, bbox, [options]);

Arguments:

  • positions (Array|TypedArray) - a flat array of the vertex positions that define the polygon.
  • bbox (Array) - the bounding box, in [minX, minY, maxX, maxY]
  • options (Object, optional)
    • size (Number) - the number of elements in each vertex. Size 2 will interpret positions as [x0, y0, x1, y1, ...] and size 3 will interpret positions as [x0, y0, z0, x1, y1, z1, ...]. Default 2.
    • startIndex (Number, optional) - the index in positions to start reading vertices. Default 0.
    • endIndex (Number, optional) - the index in positions to stop reading vertices. Default positions.length.

Returns:

A positions array that describes the intersection of the original polygon and the bounding box. Uses the same vertex size as the input.

If the input polygon does not overlap with the bounding box, an empty array will be returned.