flatten-js
Version:
Javascript library for 2d geometry
510 lines (431 loc) • 16.8 kB
JavaScript
/**
* Created by Alex Bol on 3/10/2017.
*/
"use strict";
module.exports = function (Flatten) {
/**
* Class representing a segment
* @type {Segment}
*/
Flatten.Segment = class Segment {
/**
*
* @param {Point} ps - start point
* @param {Point} pe - end point
*/
constructor(...args) {
/**
* Start point
* @type {Point}
*/
this.ps = new Flatten.Point();
/**
* End Point
* @type {Point}
*/
this.pe = new Flatten.Point();
if (args.length == 0) {
return;
}
if (args.length == 1 && args[0] instanceof Array && args[0].length == 4) {
let coords = args[0];
this.ps = new Flatten.Point(coords[0], coords[1]);
this.pe = new Flatten.Point(coords[2], coords[3]);
return;
}
if (args.length == 1 && args[0] instanceof Object && args[0].name === "segment") {
let {ps,pe} = args[0];
this.ps = new Flatten.Point(ps.x, ps.y);
this.pe = new Flatten.Point(pe.x, pe.y);
return;
}
if (args.length == 2 && args[0] instanceof Flatten.Point && args[1] instanceof Flatten.Point) {
this.ps = args[0].clone();
this.pe = args[1].clone();
return;
}
if (args.length == 4) {
this.ps = new Flatten.Point(args[0], args[1]);
this.pe = new Flatten.Point(args[2], args[3]);
return;
}
throw Flatten.Errors.ILLEGAL_PARAMETERS;
}
/**
* Method clone copies segment and returns a new instance
* @returns {Segment}
*/
clone() {
return new Flatten.Segment(this.start, this.end);
}
/**
* Start point
* @returns {Point}
*/
get start() {
return this.ps;
}
/**
* End point
* @returns {Point}
*/
get end() {
return this.pe;
}
/**
* Returns array of start and end point
* @returns [Point,Point]
*/
get vertices() {
return [this.ps.clone(), this.pe.clone()];
}
/**
* Length of a segment
* @returns {number}
*/
get length() {
return this.start.distanceTo(this.end)[0];
}
/**
* Slope of the line - angle to axe x in radians from 0 to 2PI
* @returns {number}
*/
get slope() {
let vec = new Flatten.Vector(this.start, this.end);
return vec.slope;
}
/**
* Bounding box
* @returns {Box}
*/
get box() {
return new Flatten.Box(
Math.min(this.start.x, this.end.x),
Math.min(this.start.y, this.end.y),
Math.max(this.start.x, this.end.x),
Math.max(this.start.y, this.end.y)
)
}
/**
* Returns true if equals to query segment, false otherwise
* @param {Seg} seg - query segment
* @returns {boolean}
*/
equalTo(seg) {
return this.ps.equalTo(seg.ps) && this.pe.equalTo(seg.pe);
}
/**
* Returns true if segment contains point
* @param {Point} pt Query point
* @returns {boolean}
*/
contains(pt) {
return Flatten.Utils.EQ_0(this.distanceToPoint(pt));
}
/**
* Returns array of intersection points between segment and other shape
* @param {Shape} shape - Shape of the one of supported types <br/>
* @returns {Point[]}
*/
intersect(shape) {
if (shape instanceof Flatten.Point) {
return this.contains(shape) ? [shape] : [];
}
if (shape instanceof Flatten.Line) {
return Segment.intersectSegment2Line(this, shape);
}
if (shape instanceof Flatten.Segment) {
return Segment.intersectSegment2Segment(this, shape);
}
if (shape instanceof Flatten.Circle) {
return Segment.intersectSegment2Circle(this, shape);
}
if (shape instanceof Flatten.Arc) {
return Segment.intersectSegment2Arc(this, shape);
}
if (shape instanceof Flatten.Polygon) {
return Flatten.Polygon.intersectShape2Polygon(this, shape);
}
}
/**
* Calculate distance and shortest segment from segment to shape and return as array [distance, shortest segment]
* @param {Shape} shape Shape of the one of supported types Point, Line, Circle, Segment, Arc, Polygon or Planar Set
* @returns {number} distance from segment to shape
* @returns {Segment} shortest segment between segment and shape (started at segment, ended at shape)
*/
distanceTo(shape) {
let {Distance} = Flatten;
if (shape instanceof Flatten.Point) {
let [dist, shortest_segment] = Distance.point2segment(shape, this);
shortest_segment = shortest_segment.reverse();
return [dist, shortest_segment];
}
if (shape instanceof Flatten.Circle) {
let [dist, shortest_segment] = Distance.segment2circle(this, shape);
return [dist, shortest_segment];
}
if (shape instanceof Flatten.Line) {
let [dist, shortest_segment] = Distance.segment2line(this, shape);
return [dist, shortest_segment];
}
if (shape instanceof Flatten.Segment) {
let [dist, shortest_segment] = Distance.segment2segment(this, shape);
return [dist, shortest_segment];
}
if (shape instanceof Flatten.Arc) {
let [dist, shortest_segment] = Distance.segment2arc(this, shape);
return [dist, shortest_segment];
}
if (shape instanceof Flatten.Polygon) {
let [dist, shortest_segment] = Distance.shape2polygon(this, shape);
return [dist, shortest_segment];
}
if (shape instanceof Flatten.PlanarSet) {
let [dist, shortest_segment] = Distance.shape2planarSet(this, shape);
return [dist, shortest_segment];
}
}
/**
* Returns unit vector in the direction from start to end
* @returns {Vector}
*/
tangentInStart() {
let vec = new Flatten.Vector(this.start, this.end);
return vec.normalize();
}
/**
* Return unit vector in the direction from end to start
* @returns {Vector}
*/
tangentInEnd() {
let vec = new Flatten.Vector(this.end, this.start);
return vec.normalize();
}
/**
* Returns new segment with swapped start and end points
* @returns {Segment}
*/
reverse() {
return new Segment(this.end, this.start);
}
/**
* When point belongs to segment, return array of two segments split by given point,
* if point is inside segment. Returns clone of this segment if query point is incident
* to start or end point of the segment. Returns empty array if point does not belong to segment
* @param {Point} pt Query point
* @returns {Segment[]}
*/
split(pt) {
if (!this.contains(pt))
return [];
if (this.start.equalTo(this.end))
return [this.clone()];
if (this.start.equalTo(pt) || this.end.equalTo(pt))
return [this];
return [
new Flatten.Segment(this.start, pt),
new Flatten.Segment(pt, this.end)
]
}
/**
* Return middle point of the segment
* @returns {Point}
*/
middle() {
return new Flatten.Point((this.start.x + this.end.x)/2, (this.start.y + this.end.y)/2);
}
distanceToPoint(pt) {
let [dist, ...rest] = Flatten.Distance.point2segment(pt, this);
return dist;
};
definiteIntegral(ymin = 0.0) {
let dx = this.end.x - this.start.x;
let dy1 = this.start.y - ymin;
let dy2 = this.end.y - ymin;
return ( dx * (dy1 + dy2) / 2 );
}
/**
* Returns new segment translated by vector vec
* @param {Vector} vec
* @returns {Segment}
*/
translate(...args) {
return new Segment(this.ps.translate(...args), this.pe.translate(...args));
}
/**
* Return new segment rotated by given angle around given point
* If point omitted, rotate around origin (0,0)
* Positive value of angle defines rotation counter clockwise, negative - clockwise
* @param {number} angle - rotation angle in radians
* @param {Point} center - center point, default is (0,0)
* @returns {Segment}
*/
rotate(angle = 0, center = new Flatten.Point()) {
let m = new Flatten.Matrix();
m = m.translate(center.x, center.y).rotate(angle).translate(-center.x, -center.y);
return this.transform(m);
}
/**
* Return new segment transformed using affine transformation matrix
* @param {Matrix} matrix - affine transformation matrix
* @returns {Segment} - transformed segment
*/
transform(matrix = new Flatten.Matrix()) {
return new Segment(this.ps.transform(matrix), this.pe.transform(matrix))
}
/**
* Returns true if segment start is equal to segment end up to DP_TOL
* @returns {boolean}
*/
isZeroLength() {
return this.ps.equalTo(this.pe)
}
static intersectSegment2Line(seg, line) {
let ip = [];
// Boundary cases
if (seg.ps.on(line)) {
ip.push(seg.ps);
}
// If both ends lay on line, return two intersection points
if (seg.pe.on(line) && !seg.isZeroLength()) {
ip.push(seg.pe);
}
if (ip.length > 0) {
return ip; // done, intersection found
}
// If zero-length segment and nothing found, return no intersections
if (seg.isZeroLength()) {
return ip;
}
// Not a boundary case, check if both points are on the same side and
// hence there is no intersection
if (seg.ps.leftTo(line) && seg.pe.leftTo(line) ||
!seg.ps.leftTo(line) && !seg.pe.leftTo(line)) {
return ip;
}
// Calculate intersection between lines
let line1 = new Flatten.Line(seg.ps, seg.pe);
return line1.intersect(line);
}
static intersectSegment2Segment(seg1, seg2) {
let ip = [];
// quick reject
if (seg1.box.not_intersect(seg2.box)) {
return ip;
}
// Special case of seg1 zero length
if (seg1.isZeroLength()) {
if (seg1.ps.on(seg2)) {
ip.push(seg1.ps);
}
return ip;
}
// Special case of seg2 zero length
if (seg2.isZeroLength()) {
if (seg2.ps.on(seg1)) {
ip.push(seg2.ps);
}
return ip;
}
// Neither seg1 nor seg2 is zero length
let line1 = new Flatten.Line(seg1.ps, seg1.pe);
let line2 = new Flatten.Line(seg2.ps, seg2.pe);
// Check overlapping between segments in case of incidence
// If segments touching, add one point. If overlapping, add two points
if (line1.incidentTo(line2)) {
if (seg1.ps.on(seg2)) {
ip.push(seg1.ps);
}
if (seg1.pe.on(seg2)) {
ip.push(seg1.pe);
}
if (seg2.ps.on(seg1) && !seg2.ps.equalTo(seg1.ps) && !seg2.ps.equalTo(seg1.pe)) {
ip.push(seg2.ps);
}
if (seg2.pe.on(seg1) && !seg2.pe.equalTo(seg1.ps) && !seg2.pe.equalTo(seg1.pe)) {
ip.push(seg2.pe);
}
}
else { /* not incident - parallel or intersect */
// Calculate intersection between lines
let new_ip = line1.intersect(line2);
if (new_ip.length > 0 && new_ip[0].on(seg1) && new_ip[0].on(seg2)) {
ip.push(new_ip[0]);
}
}
return ip;
}
static intersectSegment2Circle(segment, circle) {
let ips = [];
if (segment.box.not_intersect(circle.box)) {
return ips;
}
// Special case of zero length segment
if (segment.isZeroLength()) {
let [dist,shortest_segment] = segment.ps.distanceTo(circle.pc);
if (Flatten.Utils.EQ(dist, circle.r)) {
ips.push(segment.ps);
}
return ips;
}
// Non zero-length segment
let line = new Flatten.Line(segment.ps, segment.pe);
let ips_tmp = line.intersect(circle);
for (let ip of ips_tmp) {
if (ip.on(segment)) {
ips.push(ip);
}
}
return ips;
}
static intersectSegment2Arc(segment, arc) {
let ip = [];
if (segment.box.not_intersect(arc.box)) {
return ip;
}
// Special case of zero-length segment
if (segment.isZeroLength()) {
if (segment.ps.on(arc)) {
ip.push(segment.ps);
}
return ip;
}
// Non-zero length segment
let line = new Flatten.Line(segment.ps, segment.pe);
let circle = new Flatten.Circle(arc.pc, arc.r);
let ip_tmp = line.intersect(circle);
for (let pt of ip_tmp) {
if (pt.on(segment) && pt.on(arc)) {
ip.push(pt);
}
}
return ip;
}
/**
* Return string to draw segment in svg
* @param {Object} attrs - an object with attributes for svg path element,
* like "stroke", "strokeWidth" <br/>
* Defaults are stroke:"black", strokeWidth:"1"
* @returns {string}
*/
svg(attrs = {}) {
let {stroke, strokeWidth, id, className} = attrs;
// let rest_str = Object.keys(rest).reduce( (acc, key) => acc += ` ${key}="${rest[key]}"`, "");
let id_str = (id && id.length > 0) ? `id="${id}"` : "";
let class_str = (className && className.length > 0) ? `class="${className}"` : "";
return `\n<line x1="${this.start.x}" y1="${this.start.y}" x2="${this.end.x}" y2="${this.end.y}" stroke="${stroke || "black"}" stroke-width="${strokeWidth || 1}" ${id_str} ${class_str} />`;
}
/**
* This method returns an object that defines how data will be
* serialized when called JSON.stringify() method
* @returns {Object}
*/
toJSON() {
return Object.assign({},this,{name:"segment"});
}
};
/**
* Shortcut method to create new segment
*/
Flatten.segment = (...args) => new Flatten.Segment(...args);
};