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intersection.class.ts
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intersection.class.ts
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//@ts-nocheck
import { Point } from "./point.class";
import { fabric } from '../HEADER';
/* Adaptation of work of Kevin Lindsey (kevin@kevlindev.com) */
type IntersectionType = 'Intersection' | 'Coincident' | 'Parallel';
/**
* **Assuming `T`, `A`, `B` are points on the same line**,
* check if `T` is contained in `[A, B]` by comparing the direction of the vectors from `T` to `A` and `B`
* @param T
* @param A
* @param B
* @returns true if `T` is contained
*/
const isContainedInInterval = (T: Point, A: Point, B: Point) => {
const TA = new Point(T).subtract(A);
const TB = new Point(T).subtract(B);
return Math.sign(TA.x) !== Math.sign(TB.x) || Math.sign(TA.y) !== Math.sign(TB.y);
}
export class Intersection {
points: Point[]
status?: IntersectionType
constructor(status?: IntersectionType) {
this.status = status;
this.points = [];
}
/**
*
* @param {Point} point
* @returns
*/
contains(point) {
return this.points.some(p => p.eq(point));
}
/**
* Appends points of intersection
* @param {...Point[]} points
* @return {Intersection} thisArg
* @chainable
*/
private append(...points) {
this.points = this.points.concat(points.filter(point => {
return !this.contains(point);
}));
return this;
}
/**
* Checks if a line intersects another
* @static
* @param {Point} a1
* @param {Point} a2
* @param {Point} b1
* @param {Point} b2
* @param {boolean} [aIinfinite=true] check segment intersection by passing `false`
* @param {boolean} [bIinfinite=true] check segment intersection by passing `false`
* @return {Intersection}
*/
static intersectLineLine(a1, a2, b1, b2, aIinfinite = true, bIinfinite = true) {
let result;
const 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) {
const ua = uaT / uB,
ub = ubT / uB;
if ((aIinfinite || (0 <= ua && ua <= 1)) && (bIinfinite || (0 <= ub && ub <= 1))) {
result = new Intersection('Intersection');
result.append(new 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) {
const segmentsCoincide = aIinfinite || bIinfinite
|| isContainedInInterval(a1, b1, b2) || isContainedInInterval(a2, b1, b2)
|| isContainedInInterval(b1, a1, a2) || isContainedInInterval(b2, a1, a2);
result = new Intersection(segmentsCoincide ? 'Coincident' : undefined);
}
else {
result = new Intersection('Parallel');
}
}
return result;
}
/**
* Checks if a segment intersects a line
* @see {@link intersectLineLine} for line intersection
* @static
* @param {Point} s1 boundary point of segment
* @param {Point} s2 other boundary point of segment
* @param {Point} l1 point on line
* @param {Point} l2 other point on line
* @return {Intersection}
*/
static intersectSegmentLine(s1, s2, l1, l2) {
return Intersection.intersectLineLine(s1, s2, l1, l2, false, true);
}
/**
* Checks if a segment intersects another
* @see {@link intersectLineLine} for line intersection
* @static
* @param {Point} a1 boundary point of segment
* @param {Point} a2 other boundary point of segment
* @param {Point} b1 boundary point of segment
* @param {Point} b2 other boundary point of segment
* @return {Intersection}
*/
static intersectSegmentSegment(a1, a2, b1, b2) {
return Intersection.intersectLineLine(a1, a2, b1, b2, false, false);
}
/**
* Checks if line intersects polygon
*
* @todo account for stroke
*
* @static
* @see {@link intersectSegmentPolygon} for segment intersection
* @param {Point} a1 point on line
* @param {Point} a2 other point on line
* @param {Point[]} points polygon points
* @param {boolean} [infinite=true] check segment intersection by passing `false`
* @return {Intersection}
*/
static intersectLinePolygon(a1, a2, points, infinite = true) {
const result = new Intersection();
const length = points.length;
for (let i = 0, b1, b2, inter; i < length; i++) {
b1 = points[i];
b2 = points[(i + 1) % length];
inter = Intersection.intersectLineLine(a1, a2, b1, b2, infinite, false);
if (inter.status === 'Coincident') {
return inter;
}
result.append(...inter.points);
}
if (result.points.length > 0) {
result.status = 'Intersection';
}
return result;
}
/**
* Checks if segment intersects polygon
* @static
* @see {@link intersectLinePolygon} for line intersection
* @param {Point} a1 boundary point of segment
* @param {Point} a2 other boundary point of segment
* @param {Point[]} points polygon points
* @return {Intersection}
*/
static intersectSegmentPolygon(a1, a2, points) {
return Intersection.intersectLinePolygon(a1, a2, points, false);
}
/**
* Checks if polygon intersects another polygon
*
* @todo account for stroke
*
* @static
* @param {Point[]} points1
* @param {Point[]} points2
* @return {Intersection}
*/
static intersectPolygonPolygon(points1, points2) {
const result = new Intersection(),
length = points1.length;
const coincidents = [];
for (let i = 0; i < length; i++) {
const a1 = points1[i],
a2 = points1[(i + 1) % length],
inter = Intersection.intersectSegmentPolygon(a1, a2, points2);
if (inter.status === 'Coincident') {
coincidents.push(inter);
result.append(a1, a2);
}
else {
result.append(...inter.points);
}
}
if (coincidents.length > 0 && coincidents.length === points1.length) {
return new Intersection('Coincident');
}
else if (result.points.length > 0) {
result.status = 'Intersection';
}
return result;
}
/**
* Checks if polygon intersects rectangle
* @static
* @see {@link intersectPolygonPolygon} for polygon intersection
* @param {Point[]} points polygon points
* @param {Point} r1 top left point of rect
* @param {Point} r2 bottom right point of rect
* @return {Intersection}
*/
static intersectPolygonRectangle(points, r1, r2) {
const min = r1.min(r2),
max = r1.max(r2),
topRight = new Point(max.x, min.y),
bottomLeft = new Point(min.x, max.y);
return Intersection.intersectPolygonPolygon(points, [
min,
topRight,
max,
bottomLeft
]);
}
}
fabric.Intersection = Intersection;