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Changed the LineToLine intersection method to use the version created by Paul Bourke (smaller, faster, simpler).

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This commit is contained in:
Richard Davey 2017-03-31 04:33:51 +01:00
parent e6c431bfed
commit a2ba500cbe
3 changed files with 38 additions and 44 deletions
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2
v3/src/checksum.js
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@ -1,4 +1,4 @@
var CHECKSUM = {
build: '60c3d480-15b5-11e7-8f5d-bbee41a96ec7'
build: 'fb7ca1d0-15c1-11e7-a77e-25453d56c57c'
};
module.exports = CHECKSUM;

64
v3/src/geom/intersects/LineToLine.js
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@ -1,49 +1,49 @@
var Point = require('../point/Point');
// This is based off an explanation and expanded math presented by Paul Bourke:
// See http:'local.wasp.uwa.edu.au/~pbourke/geometry/lineline2d/
var LineToLine = function (line1, line2, asSegment, out)
var LineToLine = function (line1, line2, out)
{
if (asSegment === undefined) { asSegment = true; }
if (out === undefined) { out = new Point(); }
if (out === undefined) { out = { x: 0, y: 0 }; }
var a = line1.x1;
var b = line1.y1;
var x1 = line1.x1;
var y1 = line1.y1;
var x2 = line1.x2;
var y2 = line1.y2;
var x3 = line2.x1;
var y3 = line2.y1;
var x4 = line2.x2;
var y4 = line2.y2;
var e = line1.x2;
var f = line1.y2;
var numA = (x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3);
var numB = (x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3);
var deNom = (y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1);
var a1 = b.y - a.y;
var a2 = f.y - e.y;
var b1 = a.x - b.x;
var b2 = e.x - f.x;
var c1 = (b.x * a.y) - (a.x * b.y);
var c2 = (f.x * e.y) - (e.x * f.y);
var denom = (a1 * b2) - (a2 * b1);
// Make sure there is not a division by zero - this also indicates that the lines are parallel.
// If numA and numB were both equal to zero the lines would be on top of each other (coincidental).
// This check is not done because it is not necessary for this implementation (the parallel check accounts for this).
if (denom === 0)
if (deNom === 0)
{
return null;
return false;
}
out.x = ((b1 * c2) - (b2 * c1)) / denom;
out.y = ((a2 * c1) - (a1 * c2)) / denom;
// Calculate the intermediate fractional point that the lines potentially intersect.
if (asSegment)
{
var uc = ((f.y - e.y) * (b.x - a.x) - (f.x - e.x) * (b.y - a.y));
var ua = (((f.x - e.x) * (a.y - e.y)) - (f.y - e.y) * (a.x - e.x)) / uc;
var ub = (((b.x - a.x) * (a.y - e.y)) - ((b.y - a.y) * (a.x - e.x))) / uc;
var uA = numA / deNom;
var uB = numB / deNom;
if (ua >= 0 && ua <= 1 && ub >= 0 && ub <= 1)
// The fractional point will be between 0 and 1 inclusive if the lines intersect.
// If the fractional calculation is larger than 1 or smaller than 0 the lines would need to be longer to intersect.
if (uA >= 0 && uA <= 1 && uB >= 0 && uB <= 1)
{
return out;
}
else
{
return null;
}
out.x = x1 + (uA * (x2 - x1));
out.y = y1 + (uA * (y2 - y1));
return true;
}
return out;
return false;
};
module.exports = LineToLine;

16
v3/src/geom/line/Line.js
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@ -2,18 +2,12 @@
var Line = function (x1, y1, x2, y2)
{
if (x1 === undefined) { x1 = 0; }
if (y1 === undefined) { y1 = 0; }
if (x2 === undefined) { x2 = 0; }
if (y2 === undefined) { y2 = 0; }
this.x1 = 0;
this.y1 = 0;
this.x2 = 0;
this.y2 = 0;
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
this.setTo(x1, y1, x2, y2);
};
Line.prototype.constructor = Line;