flatten-js
Version:
Javascript library for 2d geometry
219 lines (200 loc) • 8.04 kB
JavaScript
/**
* Created by Alex Bol on 3/17/2017.
*/
module.exports = function(Flatten) {
/**
* Class representing an edge of polygon. Edge shape may be Segment or Arc.
* Each edge contains references to the next and previous edges in the face of the polygon.
*
* @type {Edge}
*/
Flatten.Edge = class Edge {
/**
* Construct new instance of edge
* @param {Shape} shape Shape of type Segment of Arc
*/
constructor(shape) {
/**
* Shape of the edge: Segment or Arc
*/
this.shape = shape;
/**
* Pointer to the next edge in the face
*/
this.next;
/**
* Pointer to the previous edge in the face
*/
this.prev;
/**
* Pointer to the face containing this edge
* @type {Face}
*/
this.face;
/**
* "Arc distance" from the face start
* @type {number}
*/
this.arc_length = 0;
/**
* Start inclusion flag (inside/outside/boundary)
* @type {Boolean}
*/
this.bvStart = undefined;
/**
* End inclusion flag (inside/outside/boundary)
* @type {Boolean}
*/
this.bvEnd = undefined;
/**
* Edge inclusion flag (Flatten.INSIDE, Flatten.OUTSIDE, Flatten.BOUNDARY)
* @type {*}
*/
this.bv = undefined;
/**
* Overlap flag for boundary edge (Flatten.OVERLAP_SAME/Flatten.OVERLAP_OPPOSITE)
* @type {*}
*/
this.overlap = undefined;
}
/**
* Get edge start point
*/
get start() {
return this.shape.start;
}
/**
* Get edge end point
*/
get end() {
return this.shape.end;
}
/**
* Get edge length
*/
get length() {
return this.shape.length;
}
/**
* Get bounding box of the edge
* @returns {Box}
*/
get box() {
return this.shape.box;
}
isSegment() {
return this.shape instanceof Flatten.Segment;
}
isArc() {
return this.shape instanceof Flatten.Arc;
}
/**
* Get middle point of the edge
* @returns {Point}
*/
middle() {
return this.shape.middle();
}
/**
* Returns true if point belongs to the edge, false otherwise
* @param {Point} pt - test point
*/
contains(pt) {
return this.shape.contains(pt);
}
/**
* Set inclusion flag of the edge with respect to another polygon
* Inclusion flag is one of Flatten.INSIDE, Flatten.OUTSIDE, Flatten.BOUNDARY
* @param polygon
*/
setInclusion(polygon) {
if (this.bv !== undefined) return this.bv;
if (this.bvStart === undefined) {
this.bvStart = Flatten.ray_shoot(polygon, this.start);
}
if (this.bvEnd === undefined) {
this.bvEnd = Flatten.ray_shoot(polygon, this.end);
}
/* At least one end outside - the whole edge outside */
if (this.bvStart === Flatten.OUTSIDE || this.bvEnd == Flatten.OUTSIDE) {
this.bv = Flatten.OUTSIDE;
}
/* At least one end inside - the whole edge inside */
else if (this.bvStart === Flatten.INSIDE || this.bvEnd == Flatten.INSIDE) {
this.bv = Flatten.INSIDE;
}
/* Both are boundary - check the middle point */
else {
let bvMiddle = Flatten.ray_shoot(polygon, this.middle());
this.bv = bvMiddle;
}
return this.bv;
}
/**
* Set overlapping between two coincident boundary edges
* Overlapping flag is one of Flatten.OVERLAP_SAME or Flatten.OVERLAP_OPPOSITE
* @param edge
*/
setOverlap(edge) {
let flag = undefined;
let shape1 = this.shape;
let shape2 = edge.shape;
if (shape1 instanceof Flatten.Segment && shape2 instanceof Flatten.Segment) {
if (shape1.start.equalTo(shape2.start) && shape1.end.equalTo(shape2.end)) {
flag = Flatten.OVERLAP_SAME;
}
else if (shape1.start.equalTo(shape2.end) && shape1.end.equalTo(shape2.start)) {
flag = Flatten.OVERLAP_OPPOSITE;
}
}
else if (shape1 instanceof Flatten.Arc && shape2 instanceof Flatten.Arc) {
if (shape1.start.equalTo(shape2.start) && shape1.end.equalTo(shape2.end) && /*shape1.counterClockwise === shape2.counterClockwise &&*/
shape1.middle().equalTo(shape2.middle())) {
flag = Flatten.OVERLAP_SAME;
}
else if (shape1.start.equalTo(shape2.end) && shape1.end.equalTo(shape2.start) && /*shape1.counterClockwise !== shape2.counterClockwise &&*/
shape1.middle().equalTo(shape2.middle())) {
flag = Flatten.OVERLAP_OPPOSITE;
}
}
else if (shape1 instanceof Flatten.Segment && shape2 instanceof Flatten.Arc ||
shape1 instanceof Flatten.Arc && shape2 instanceof Flatten.Segment) {
if (shape1.start.equalTo(shape2.start) && shape1.end.equalTo(shape2.end) && shape1.middle().equalTo(shape2.middle())) {
flag = Flatten.OVERLAP_SAME;
}
else if (shape1.start.equalTo(shape2.end) && shape1.end.equalTo(shape2.start) && shape1.middle().equalTo(shape2.middle())) {
flag = Flatten.OVERLAP_OPPOSITE;
}
}
/* Do not update overlap flag if already set on previous chain */
if (this.overlap === undefined) this.overlap = flag;
if (edge.overlap === undefined) edge.overlap = flag;
}
svg() {
if (this.shape instanceof Flatten.Segment) {
return ` L${this.shape.end.x},${this.shape.end.y}`;
}
else if (this.shape instanceof Flatten.Arc) {
let arc = this.shape;
let largeArcFlag;
let sweepFlag = arc.counterClockwise ? "1" : "0";
// Draw full circe arc as special case: split it into two half-circles
if (Flatten.Utils.EQ(arc.sweep, 2*Math.PI)) {
let sign = arc.counterClockwise ? 1 : -1;
let halfArc1 = new Flatten.Arc(arc.pc, arc.r, arc.startAngle, arc.startAngle + sign*Math.PI, arc.counterClockwise);
let halfArc2 = new Flatten.Arc(arc.pc, arc.r, arc.startAngle + sign*Math.PI, arc.endAngle, arc.counterClockwise);
largeArcFlag = "0";
return ` A${halfArc1.r},${halfArc1.r} 0 ${largeArcFlag},${sweepFlag} ${halfArc1.end.x},${halfArc1.end.y}
A${halfArc2.r},${halfArc2.r} 0 ${largeArcFlag},${sweepFlag} ${halfArc2.end.x},${halfArc2.end.y}`
}
else {
largeArcFlag = arc.sweep <= Math.PI ? "0" : "1";
return ` A${arc.r},${arc.r} 0 ${largeArcFlag},${sweepFlag} ${arc.end.x},${arc.end.y}`;
}
}
}
toJSON() {
return this.shape.toJSON();
}
};
};