Package Exports

intersection

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (intersection) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

intersection

var intersection = require('intersection');
var seg2 = {start:{x:-1,y:2}, end:{x:5,y:2}};
var seg3 = {start:{x:1,y:-1}, end:{x:4,y:4}};

intersection.intersect(seg2,seg3); 
// {x:2.8,y:2}

.intersect(a,b)

.intersect(a,b) takes two line segments a and b and returns their point of intersection. Returns false if they are collinear or parallel.

.describe(a,b)

.describe(a,b) takes two line segments a and b and returns a report about thier co-linearity, if they are parallel, and the intersection if defined.

var segA = {start:{x:3,y:0},end:{x:3,y:4}};

// colinear with segA
var segA_1 = {start:{x:3,y:-2},end:{x:3, y:9}};

// parallel but not colinear with seg1
var segA_2 = {start:{x:1, y:-1}, end:{x:1, y:5}};

intersection.describe(segA,segA_1);
// {colinear:true, parallel:true,intersection:undefined}

intersection.describe(segA,segA_2);
// {colinear:false, parallel:true,intersection:undefined}

intersection.describe(segA,segB);
// {colinear:false, parallel:false, intersection:{x:2.8,y:2}

.isParallel(a,b)

Returns true if a and b are parallel line segments, false otherwise.

.isCollinear(a,b)

Returns true if a and b are collinear line segments, false otherwise. Collinear segments means the segments lie on the same line.

Notes

.intersect returns false if the two segments are co-linear or parallel.

Notes II

Intersection utilizes the fast cross-product method as outlined by Ronald Grahm in "Graphics Gems I".

Test Results and Benchmarks

From nodeunit test/test.js

nodeunit test.js 

test.js
✔ descriptionTest
✔ basicTest
✔ safeIntersectionTest
✔ testReadmeExamples

OK: 13 assertions (21ms)

TODO

There is a speed boost outlined by Mukesh Prasad in "Graphics Gems II" utilizing a same-side sign test.