intersection.class.js
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(function(global) {
'use strict';
/* Adaptation of work of Kevin Lindsey (kevin@kevlindev.com) */
var fabric = global.fabric || (global.fabric = { });
if (fabric.Intersection) {
fabric.warn('fabric.Intersection is already defined');
return;
}
/**
* Intersection class
* @class fabric.Intersection
* @memberOf fabric
* @constructor
*/
function Intersection(status) {
this.status = status;
this.points = [];
}
fabric.Intersection = Intersection;
fabric.Intersection.prototype = /** @lends fabric.Intersection.prototype */ {
constructor: Intersection,
/**
* Appends a point to intersection
* @param {fabric.Point} point
* @return {fabric.Intersection} thisArg
* @chainable
*/
appendPoint: function (point) {
this.points.push(point);
return this;
},
/**
* Appends points to intersection
* @param {Array} points
* @return {fabric.Intersection} thisArg
* @chainable
*/
appendPoints: function (points) {
this.points = this.points.concat(points);
return this;
}
};
/**
* Checks if one line intersects another
* TODO: rename in intersectSegmentSegment
* @static
* @param {fabric.Point} a1
* @param {fabric.Point} a2
* @param {fabric.Point} b1
* @param {fabric.Point} b2
* @return {fabric.Intersection}
*/
fabric.Intersection.intersectLineLine = function (a1, a2, b1, b2) {
var result,
uaT = (b2.x - b1.x) * (a1.y - b1.y) - (b2.y - b1.y) * (a1.x - b1.x),
ubT = (a2.x - a1.x) * (a1.y - b1.y) - (a2.y - a1.y) * (a1.x - b1.x),
uB = (b2.y - b1.y) * (a2.x - a1.x) - (b2.x - b1.x) * (a2.y - a1.y);
if (uB !== 0) {
var ua = uaT / uB,
ub = ubT / uB;
if (0 <= ua && ua <= 1 && 0 <= ub && ub <= 1) {
result = new Intersection('Intersection');
result.appendPoint(new fabric.Point(a1.x + ua * (a2.x - a1.x), a1.y + ua * (a2.y - a1.y)));
}
else {
result = new Intersection();
}
}
else {
if (uaT === 0 || ubT === 0) {
result = new Intersection('Coincident');
}
else {
result = new Intersection('Parallel');
}
}
return result;
};
/**
* Checks if line intersects polygon
* TODO: rename in intersectSegmentPolygon
* fix detection of coincident
* @static
* @param {fabric.Point} a1
* @param {fabric.Point} a2
* @param {Array} points
* @return {fabric.Intersection}
*/
fabric.Intersection.intersectLinePolygon = function(a1, a2, points) {
var result = new Intersection(),
length = points.length,
b1, b2, inter, i;
for (i = 0; i < length; i++) {
b1 = points[i];
b2 = points[(i + 1) % length];
inter = Intersection.intersectLineLine(a1, a2, b1, b2);
result.appendPoints(inter.points);
}
if (result.points.length > 0) {
result.status = 'Intersection';
}
return result;
};
/**
* Checks if polygon intersects another polygon
* @static
* @param {Array} points1
* @param {Array} points2
* @return {fabric.Intersection}
*/
fabric.Intersection.intersectPolygonPolygon = function (points1, points2) {
var result = new Intersection(),
length = points1.length, i;
for (i = 0; i < length; i++) {
var a1 = points1[i],
a2 = points1[(i + 1) % length],
inter = Intersection.intersectLinePolygon(a1, a2, points2);
result.appendPoints(inter.points);
}
if (result.points.length > 0) {
result.status = 'Intersection';
}
return result;
};
/**
* Checks if polygon intersects rectangle
* @static
* @param {Array} points
* @param {fabric.Point} r1
* @param {fabric.Point} r2
* @return {fabric.Intersection}
*/
fabric.Intersection.intersectPolygonRectangle = function (points, r1, r2) {
var min = r1.min(r2),
max = r1.max(r2),
topRight = new fabric.Point(max.x, min.y),
bottomLeft = new fabric.Point(min.x, max.y),
inter1 = Intersection.intersectLinePolygon(min, topRight, points),
inter2 = Intersection.intersectLinePolygon(topRight, max, points),
inter3 = Intersection.intersectLinePolygon(max, bottomLeft, points),
inter4 = Intersection.intersectLinePolygon(bottomLeft, min, points),
result = new Intersection();
result.appendPoints(inter1.points);
result.appendPoints(inter2.points);
result.appendPoints(inter3.points);
result.appendPoints(inter4.points);
if (result.points.length > 0) {
result.status = 'Intersection';
}
return result;
};
})(typeof exports !== 'undefined' ? exports : this);