pokeyjs

A linear algebra/geometry library for JavaScript.

Current Version: 0.1.2 beta

Usage

Points (2D Only)

Creating Points

var p1 = Point.create(5,6);
var p2 = Point.create(5.7,6.2);
var p3 = Point.create(p1);
var p4 = Point.create("5.8,6.1");
var p5 = Point.create({x: 17, y:19});

Distance Between Points

var distance = p1.distance(p2);

Midpoint Between Points

var mid = p1.midpoint(p2);

Comparing Points

if (p1.isLeftOf(p2)) { }
if (p1.isRightOf(p2)) { }
if (p1.isAbove(p2)) { }
if (p1.isBelow(p2)) { }
if (p1.equals(p2)) { }

Reading Point Values

var x = p1.x;
var y = p1.y;
var s = p1.toString(); // Returns a comma-delimited string like this: "5,7"

Modifying Point Values

p1.addX(5);
p1.addY(6);
p1.update(5,6);

Line Segments

Creating Line Segments

var line1 = LineSegment.create(startPoint, endPoint);
var line2 = LineSegment.create({pointA: startPoint, pointB: endPoint});
var line3 = LineSegment.create({pointA: startPoint, slope: 1, length: 12});
var line4 = LineSegment.create({pointB: endPoint, directionVector: Point.create(0,-1), length: 100});
var line5 = LineSegment.create({pointA: startPoint, angle: 180, length: 10});

Retrieving Line Data

var startPoint = line.pointA;
var endPoint = line.pointB;
var mid = line.midpoint();
var length = line.length();
var angle = line.angle(); // In Degrees
var slope = line.slope();
var yIntercept = line.yIntercept();
var vector = line.directionVector(); // Returns a point object, such as (0,1) for vertical lines.

Determining Distance from a Point

var distance = line.distance(point);

Retrieving a Point on a Line Segment

var startPoint = line.point(0); // Same as: line.pointA;
var endPoint = line.point(1); // Same as: line.pointB;
var mid = line.point(0.5); // Same as: line.midpoint();
var point75 = line.point(0.75); // Returns the point 75% of the way from pointA to pointB

Retrieving Perpendicular Points off a Line Segment

var line = LineSegment.create(Point.create(10,10), Point.create(20,10));
var mid = line.midpoint(); // Returns (15,10)
var points[] = line.pointsOffLine(mid, 5); // Returns: [(15,15), (15,5)];

Building a Perpendicular Line Segment

var line1 = LineSegment.create(Point.create(0,0), Point.create(10,0));
var line2 = line1.perp(); // returns a line segment from (5,-5) to (5,5)

By default perp() returns a perpendicular line segment that shares the same midpoint as the original line. However, you can choose to rotate around any point: var line1 = LineSegment.create(Point.create(0,0), Point.create(10,0)); var line2 = line1.perp(line1.pointA); // returns a line segment from (0,-5) to (0,5)

You can also change the length of the perpendicular line segment: var line1 = LineSegment.create(Point.create(0,0), Point.create(10,0)); var line2 = line1.perp(line1.pointA, 20); // returns a line segment from (0,-10) to (0,10)

Manipulating a Line Segment

line.grow(10); // Increases the length of the line segment by 10 units
line.grow("10%"); // Increases the length of the line segment by 10%
line.shrink(5);
line.shrink("5%");
line.rotate(90);
line.rotate(-45);

Bezier Curves

Creating a Bezier Curve

var anchor1 = Point.create(0,0);
var control1 = Point.create(5,10);
var control2 = Point.create(7,3);
var anchor2 = Point.create(12,8);
var bezier = BezierCurve.create(anchor1, control1, control2, anchor2);

Obtaining a Point on the Curve

var p1 = bezier.point(0); // returns the first anchor point
var p2 = bezier.point(1); // returns the last anchor point
var p3 = bezier.point(0.75); // demonstrating that you can request any arbitrary point along the path

Obtaining the SVG Path for the Curve

var svg = beizer.svg();

Turning a Bezier Curve into an Array of Points

var start = 0;
var end = 1;
var increment = 0.05;
var points = bezier.points(start, end, increment);

Polygons

Creating a Polygon

var poly = Polygon.create();

Adding Points to a Polygon

poly.addPoint(5,5);
poly.addPoint(10,5);
poly.addPoint(Point.create(10,10));
poly.addPoint(Point.create(5,10));

Determining if a Point Lies within a Polygon

if (poly.surrounds(point)) { }

Determining the Area of a Polygon

var area = poly.area();

Release History

• August 7, 2011: (0.1 beta) This library meets my needs at the moment, but it's far from being a complete linear algebra / vector math / geometry library.

License

Copyright (c) 2011 Michael Righi

Released under the MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.