geometry

2d cartesian geometry utils used by map.

Install

$ npm install --save @mapwhit/geometry

API

findPoleOfInaccessibility(polygonRings, precision = 1)

Finds an approximation of a polygon's Pole Of Inaccessibility.

polygonRings [[{x, y}]] : First item in array is the outer ring followed optionally by the list of holes.
precision number : Optional, default 1. Specified in input coordinate units.

Returns {x, y} - Pole of Inaccessibiliy.

distToSegmentSquared(p, v, w)

Calculates the squared distance from a point to a line segment.

p {x, y} : Point to measure from.
v {x, y} : Start point of line segment.
w {x, y} : End point of line segment.

Returns number - Squared distance from point to closest point on line segment.

polygonIntersectsPolygon(polygonA, polygonB)

Tests if two polygons intersect by checking point containment and line intersections.

polygonA [{x, y}] : First polygon as array of points.
polygonB [{x, y}] : Second polygon as array of points.

Returns boolean - True if polygons intersect.

polygonIntersectsBufferedPoint(polygon, point, radius)

Tests if a polygon intersects with a buffered point (point with radius).

polygon [{x, y}] : Polygon as array of points.
point {x, y} : Point to test.
radius number : Buffer radius around the point.

Returns boolean - True if polygon intersects the buffered point.

polygonIntersectsMultiPolygon(polygon, multiPolygon)

Tests if a polygon intersects with a multi-polygon (array of polygon rings).

polygon [{x, y}] : Polygon as array of points.
multiPolygon [[{x, y}]] : Array of polygon rings.

Returns boolean - True if polygon intersects any ring of the multi-polygon.

polygonIntersectsBufferedMultiLine(polygon, multiLine, radius)

Tests if a polygon intersects with a buffered multi-line (multiple line strings with radius).

polygon [{x, y}] : Polygon as array of points.
multiLine [[{x, y}]] : Array of line strings.
radius number : Buffer radius around the lines.

Returns boolean - True if polygon intersects the buffered multi-line.

polygonIntersectsBox(ring, boxX1, boxY1, boxX2, boxY2)

Tests if a polygon intersects with a bounding box.

ring [{x, y}] : Polygon as array of points.
boxX1 number : Left edge of bounding box.
boxY1 number : Bottom edge of bounding box.
boxX2 number : Right edge of bounding box.
boxY2 number : Top edge of bounding box.

Returns boolean - True if polygon intersects the bounding box.

isCounterClockwise(a, b, c)

Indicates if the provided Points are in a counter clockwise (true) or clockwise (false) order.

a {x, y} : First point
b {x, y} : Second point
c {x, y} : Third point

Returns boolean - True for a counter clockwise set of points, false for clockwise or collinear.

calculateSignedArea(ring)

Returns the signed area for the polygon ring. Positive areas are exterior rings and have a clockwise winding. Negative areas are interior rings and have a counter clockwise ordering.

ring [{x, y}] : Exterior or interior ring as array of points

Returns number - Signed area of the polygon ring.

isClosedPolygon(points)

Detects closed polygons where first + last point are equal and area is above threshold.

points [{x, y}] : Array of points forming the polygon.

Returns boolean - True if the points form a closed polygon with sufficient area.

clipLine(lines, x1, y1, x2, y2)

Returns the part of a multiline that intersects with the provided rectangular box.

lines [[{x, y}]] : Array of line strings, each consisting of points with x, y coordinates.
x1 number : The left edge of the bounding box.
y1 number : The top edge of the bounding box.
x2 number : The right edge of the bounding box.
y2 number : The bottom edge of the bounding box.

Returns [[{x, y}]] - Array of clipped line strings that fall within the bounding box.

License

BSD-3-Clause © 2025 Damian Krzeminski
BSD-3-Clause © 2016 Mapbox