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org.opentripplanner.visibility.LineSegment Maven / Gradle / Ivy
package org.opentripplanner.visibility;
/**
Ported by David Turner from Visilibity, by Karl J. Obermeyer
This port undoubtedly introduced a number of bugs (and removed some features).
Bug reports should be directed to the OpenTripPlanner project, unless they
can be reproduced in the original VisiLibity.
*/
public class LineSegment {
VLPoint[] endpoints;
double distance(VLPoint point_temp) {
return point_temp.distance(this);
}
LineSegment() {
endpoints = null;
}
public int size() {
if (endpoints == null) {
return 0;
} else {
return endpoints.length;
}
}
LineSegment(LineSegment line_segment_temp) {
switch (line_segment_temp.size()) {
case 0:
endpoints = null;
break;
case 1:
endpoints = new VLPoint[1];
endpoints[0] = line_segment_temp.endpoints[0].clone();
break;
case 2:
endpoints = new VLPoint[2];
endpoints[0] = line_segment_temp.endpoints[0].clone();
endpoints[1] = line_segment_temp.endpoints[1].clone();
}
}
LineSegment(VLPoint point_temp) {
endpoints = new VLPoint[1];
endpoints[0] = point_temp;
}
LineSegment(VLPoint first_point_temp, VLPoint second_point_temp) {
this(first_point_temp, second_point_temp, 0);
}
LineSegment(VLPoint first_point_temp, VLPoint second_point_temp, double epsilon) {
if (first_point_temp.distance(second_point_temp) <= epsilon) {
endpoints = new VLPoint[1];
endpoints[0] = first_point_temp;
} else {
endpoints = new VLPoint[2];
endpoints[0] = first_point_temp;
endpoints[1] = second_point_temp;
}
}
VLPoint first() {
assert (size() > 0);
return endpoints[0];
}
VLPoint second() {
assert (size() > 0);
if (size() == 2)
return endpoints[1];
else
return endpoints[0];
}
VLPoint midpoint() {
assert (size() > 0);
return first().plus(second()).times(0.5);
}
double length() {
assert (size() > 0);
return first().distance(second());
}
boolean is_in_standard_form() {
assert (size() > 0);
if (size() < 2)
return true;
return first().compareTo(second()) <= 0;
}
/*
* assignment operator -- need to audit what's going on with this -DMT LineSegment& operator =
* (const LineSegment& line_segment_temp) { //Makes sure not to delete dynamic vars before
* they're copied. if(this==&line_segment_temp) return *this; delete [] endpoints;
* switch(line_segment_temp.size_){ case 0: endpoints = null; size_ = 0; break; case 1:
* endpoints = new Point[1]; endpoints[0] = line_segment_temp.endpoints[0]; size_ = 1; break;
* case 2: endpoints = new Point[2]; endpoints[0] = line_segment_temp.endpoints[0]; endpoints[1]
* = line_segment_temp.endpoints[1]; size_ = 2; } return *this; }
*/
void set_first(VLPoint point_temp, double epsilon) {
VLPoint second_point_temp;
switch (size()) {
case 0:
endpoints = new VLPoint[1];
endpoints[0] = point_temp;
break;
case 1:
if (endpoints[0].distance(point_temp) <= epsilon) {
endpoints[0] = point_temp;
return;
}
second_point_temp = endpoints[0];
endpoints = new VLPoint[2];
endpoints[0] = point_temp;
endpoints[1] = second_point_temp;
break;
case 2:
if (point_temp.distance(endpoints[1]) > epsilon) {
endpoints[0] = point_temp;
return;
}
endpoints = new VLPoint[1];
endpoints[0] = point_temp;
}
}
void set_second(VLPoint point_temp, double epsilon) {
VLPoint first_point_temp;
switch (size()) {
case 0:
endpoints = new VLPoint[1];
endpoints[0] = point_temp;
break;
case 1:
if (endpoints[0].distance(point_temp) <= epsilon) {
endpoints[0] = point_temp;
return;
}
first_point_temp = endpoints[0];
endpoints = new VLPoint[2];
endpoints[0] = first_point_temp;
endpoints[1] = point_temp;
break;
case 2:
if (endpoints[0].distance(point_temp) > epsilon) {
endpoints[1] = point_temp;
return;
}
endpoints = new VLPoint[1];
endpoints[0] = point_temp;
break;
}
}
void reverse() {
if (size() < 2)
return;
VLPoint point_temp = endpoints[0];
endpoints[0] = endpoints[1];
endpoints[1] = point_temp;
}
void enforce_standard_form() {
if (first().compareTo(second()) > 0)
reverse();
}
void clear() {
endpoints = null;
}
public boolean equals(Object o) {
if (!(o instanceof LineSegment)) {
return false;
}
LineSegment line_segment2 = (LineSegment) o;
if (size() != line_segment2.size() || size() == 0 || line_segment2.size() == 0)
return false;
else
return (first().equals(line_segment2.first()) && second()
.equals(line_segment2.second()));
}
boolean equivalent(LineSegment line_segment2, double epsilon) {
if (size() != line_segment2.size() || size() == 0 || line_segment2.size() == 0)
return false;
else
return (first().distance(line_segment2.first()) <= epsilon && second().distance(
line_segment2.second()) <= epsilon)
|| (first().distance(line_segment2.second()) <= epsilon && second().distance(
line_segment2.first()) <= epsilon);
}
double distance(LineSegment line_segment2) {
assert (size() > 0 && line_segment2.size() > 0);
if (intersect_proper(line_segment2))
return 0;
// But if two line segments intersect improperly, the distance
// between them is equal to the minimum of the distances between
// all 4 endpoints and their respective projections onto the line
// segment they don't belong to.
double running_min, distance_temp;
running_min = first().distance(line_segment2);
distance_temp = second().distance(line_segment2);
if (distance_temp < running_min)
running_min = distance_temp;
distance_temp = line_segment2.first().distance(this);
if (distance_temp < running_min)
running_min = distance_temp;
distance_temp = line_segment2.second().distance(this);
if (distance_temp < running_min)
return distance_temp;
return running_min;
}
double boundary_distance(VLPolygon polygon) {
assert (size() > 0 && polygon.n() > 0);
double running_min = distance(polygon.get(0));
if (polygon.n() > 1)
for (int i = 0; i < polygon.n(); i++) {
double d = distance(new LineSegment(polygon.get(i), polygon.get(i + 1)));
if (running_min > d)
running_min = d;
}
return running_min;
}
boolean intersect(LineSegment line_segment2, double epsilon) {
if (size() == 0 || line_segment2.size() == 0)
return false;
if (distance(line_segment2) <= epsilon)
return true;
return false;
}
boolean intersect_proper(LineSegment line_segment2) {
return intersect_proper(line_segment2, 0);
}
boolean intersect_proper(LineSegment line_segment2, double epsilon) {
if (size() == 0 || line_segment2.size() == 0)
return false;
// Declare new vars just for readability.
VLPoint a = new VLPoint(first());
VLPoint b = new VLPoint(second());
VLPoint c = new VLPoint(line_segment2.first());
VLPoint d = new VLPoint(line_segment2.second());
// First find the minimum of the distances between all 4 endpoints
// and their respective projections onto the opposite line segment.
double running_min, distance_temp;
running_min = a.distance(line_segment2);
distance_temp = b.distance(line_segment2);
if (distance_temp < running_min)
running_min = distance_temp;
distance_temp = c.distance(this);
if (distance_temp < running_min)
running_min = distance_temp;
distance_temp = d.distance(this);
if (distance_temp < running_min)
running_min = distance_temp;
// If an endpoint is close enough to the other segment, the
// intersection is not considered proper.
if (running_min <= epsilon)
return false;
// This test is from O'Rourke's "Computational Geometry in C",
// p.30. Checks left and right turns.
if (b.minus(a).cross(c.minus(b)) * b.minus(a).cross(d.minus(b)) < 0
&& d.minus(c).cross(b.minus(d)) * d.minus(c).cross(a.minus(d)) < 0)
return true;
return false;
}
LineSegment intersection(LineSegment line_segment2, double epsilon) {
// Initially empty.
LineSegment line_segment_temp = new LineSegment();
if (size() == 0 || line_segment2.size() == 0)
return line_segment_temp;
// No intersection => return empty segment.
if (!intersect(line_segment2, epsilon))
return line_segment_temp;
// Declare new vars just for readability.
VLPoint a = new VLPoint(first());
VLPoint b = new VLPoint(second());
VLPoint c = new VLPoint(line_segment2.first());
VLPoint d = new VLPoint(line_segment2.second());
if (intersect_proper(line_segment2, epsilon)) {
// Use formula from O'Rourke's "Computational Geometry in C", p. 221.
// Note D=0 iff the line segments are parallel.
double D = a.x * (d.y - c.y) + b.x * (c.y - d.y) + d.x * (b.y - a.y) + c.x
* (a.y - b.y);
double s = (a.x * (d.y - c.y) + c.x * (a.y - d.y) + d.x * (c.y - a.y)) / D;
line_segment_temp.set_first(a.plus(b.minus(a).times(s)), epsilon);
return line_segment_temp;
}
// Otherwise if improper...
double distance_temp_a = a.distance(line_segment2);
double distance_temp_b = b.distance(line_segment2);
double distance_temp_c = c.distance(this);
double distance_temp_d = d.distance(this);
// Check if the intersection is nondegenerate segment.
if (distance_temp_a <= epsilon && distance_temp_b <= epsilon) {
line_segment_temp.set_first(a, epsilon);
line_segment_temp.set_second(b, epsilon);
return line_segment_temp;
} else if (distance_temp_c <= epsilon && distance_temp_d <= epsilon) {
line_segment_temp.set_first(c, epsilon);
line_segment_temp.set_second(d, epsilon);
return line_segment_temp;
} else if (distance_temp_a <= epsilon && distance_temp_c <= epsilon) {
line_segment_temp.set_first(a, epsilon);
line_segment_temp.set_second(c, epsilon);
return line_segment_temp;
} else if (distance_temp_a <= epsilon && distance_temp_d <= epsilon) {
line_segment_temp.set_first(a, epsilon);
line_segment_temp.set_second(d, epsilon);
return line_segment_temp;
} else if (distance_temp_b <= epsilon && distance_temp_c <= epsilon) {
line_segment_temp.set_first(b, epsilon);
line_segment_temp.set_second(c, epsilon);
return line_segment_temp;
} else if (distance_temp_b <= epsilon && distance_temp_d <= epsilon) {
line_segment_temp.set_first(b, epsilon);
line_segment_temp.set_second(d, epsilon);
return line_segment_temp;
}
// Check if the intersection is a single point.
else if (distance_temp_a <= epsilon) {
line_segment_temp.set_first(a, epsilon);
return line_segment_temp;
} else if (distance_temp_b <= epsilon) {
line_segment_temp.set_first(b, epsilon);
return line_segment_temp;
} else if (distance_temp_c <= epsilon) {
line_segment_temp.set_first(c, epsilon);
return line_segment_temp;
} else if (distance_temp_d <= epsilon) {
line_segment_temp.set_first(d, epsilon);
return line_segment_temp;
}
return line_segment_temp;
}
LineSegment intersection(Ray ray_temp, double epsilon) {
return ray_temp.intersection(this, epsilon);
}
LineSegment intersection(Ray ray_temp) {
return ray_temp.intersection(this, 0);
}
public String toString() {
switch (size()) {
case 0:
return "";
case 1:
case 2:
return first() + "\n" + second() + "\n";
default:
throw new IllegalArgumentException();
}
}
}
