File:Polygon.js
/**
* @module Native Display
* @namespace springroll.native
* @requires Core
*/
(function()
{
/**
* @class Polygon
* @constructor
* @param points* {Array<Point>|Array<Number>|Point...|Number...} This can be an array of Points that form the polygon,
* a flat array of numbers that will be interpreted as [x,y, x,y, ...], or the arguments passed can be
* all the points of the polygon e.g. `new Polygon(new Point(), new Point(), ...)`, or the
* arguments passed can be flat x,y values e.g. `new Polygon(x,y, x,y, x,y, ...)` where `x` and `y` are
* Numbers.
*/
var Polygon = function(points)
{
//if points isn't an array, use arguments as the array
if (!(points instanceof Array))
points = Array.prototype.slice.call(arguments);
//if this is a flat array of numbers, convert it to points
if (typeof points[0] === 'number')
{
var p = [];
for (var i = 0, len = points.length; i < len; i += 2)
{
p.push(
new Point(points[i], points[i + 1])
);
}
points = p;
}
this.points = points;
};
var p = extend(Polygon);
/**
* Creates a clone of this polygon
*
* @method clone
* @return {Polygon} a copy of the polygon
*/
p.clone = function()
{
var points = [];
for (var i = 0, len = this.points.length; i < len; i++)
{
points.push(this.points[i].clone());
}
return new Polygon(points);
};
/**
* Checks if the x, and y coords passed to this function are contained within this polygon
*
* @method contains
* @param x {Number} The X coord of the point to test
* @param y {Number} The Y coord of the point to test
* @return {Boolean} if the x/y coords are within this polygon
*/
p.contains = function(x, y)
{
var inside = false;
// use some raycasting to test hits
// https://github.com/substack/point-in-polygon/blob/master/index.js
var p = this.points;
var pi, pj, xi, yi, xj, yj, intersect;
for (var i = 0, len = p.length, j = p.length - 1; i < len; j = i++)
{
pi = p[i];
pj = p[j];
xi = pi.x;
yi = pi.y;
xj = pj.x;
yj = pj.y;
intersect = ((yi > y) != (yj > y)) && (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
if (intersect) inside = !inside;
}
return inside;
};
// constructor
p.constructor = Polygon;
// Assign to namespace
namespace('springroll.native').Polygon = Polygon;
}());