line-intersect

Line vs line, point vs line in 2D space

Math is mostly from here.

Install

npm install line-intersect

API

es modules

import {
  checkIntersection,
  colinearPointWithinSegment
} from 'line-intersect';

commonjs modules

const {
  checkIntersection,
  colinearPointWithinSegment
} = require('line-intersect');

checkIntersection(x1, y1, x2, y2, x3, y3, x4, y4)

Given a line segment from (x1, y1) to (x2, y2) and line segment from (x3, y3) to (x4, y4), check if the line segments intersect.

Parameters

• x1, y1, x2, y2 - 1st line segment
• x3, y3, x4, y4 - 2nd line segment

All params are Numbers and are required.

Returns

A read-only Object that looks like

{
  type: 'none' | 'parallel' | 'colinear'
}

// or

{
  type: 'intersecting',
  point: {
    x: number,
    y: number
  }
}

point is only exists when type == 'intersecting'

| type | What it means | Are the line segments touching? | |-----------------|-----------------------------------------------------------------------|----| | none | Line segments are not intersecting | No | | parallel | Line segments are not intersecting but they are parallel to eachother | No | | colinear | Line segments are on the same line and may be overlapping. Use colinearPointWithinSegment() to check | Maybe | | intersecting | Line segments intersect at exactly one point | Yes |

colinearPointWithinSegment(px, py, x1, y1, x2, y2)

Given a point (px, py) that is on the same line as line segment (x1, y1) to (x2, y2), check if the point is within the line segment.

Parameters

• px, py - Point to check
• x1, y1, x2, y2 - Line segment

All params are Numbers and are required.

Returns

true if point is within the line segment, false otherwise.

License

MIT