java.lang.Object
- cds.healpix.common.sphgeom.Polygon

```
public final class Polygon
extends java.lang.Object
```
Class defining (and storing the vertices of) a polygon on the unit sphere. The original 2D method comes from https://wrf.ecse.rpi.edu//Research/Short_Notes/pnpoly.html We adapted it here to the case of the sphere. Remark: in the case of polygons having all their points on a semi-hemisphere, we could have use the classical 2D algorithm on the points projected on a plane by the Gnomonic projections (centered to the center of the MEC). In the gnomonic projection, all great circles arc are strait lines.

Author:

F.-X. Pineau

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class Polygon.ContainsSouthPoleComputer
Defines the method used to know if the south pole is in the polygon or in its complement.

Constructor Summary

Constructors
Constructor	Description
`Polygon(CooXYZ[] polyVertices)`	Create a new polygon from the given list of vertices, using the `Polygon.ContainsSouthPoleComputer.BASIC` method to define its inside and outside.
`Polygon(CooXYZ[] polyVertices, Polygon.ContainsSouthPoleComputer cspc)`	Create a new polygon from the given list of vertices, using the given method to define its inside and outside.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`contains(CooXYZ p)`	Returns `true` if the polygon contain the point p.
`boolean`	`intersectSegAB(CooXYZ a, CooXYZ b)`	Returns `true` if an edge of the polygone intersects the line defined by the two given points.
`int`	`nVertices()`	Returns the number of vertices the polygon contains.
`CooXYZ`	`vertex(int vertexIndex)`	Returns the vertex located at the given index in the polygin vertex list.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Polygon
```
public Polygon(CooXYZ[] polyVertices)
```
    Create a new polygon from the given list of vertices, using the Polygon.ContainsSouthPoleComputer.BASIC method to define its inside and outside.
    
    Parameters:
    
    polyVertices - vertices defining the polygon
  - Polygon
```
public Polygon(CooXYZ[] polyVertices,
               Polygon.ContainsSouthPoleComputer cspc)
```
    Create a new polygon from the given list of vertices, using the given method to define its inside and outside. WARNING: so far the algorithm compute a minimum encoding cone and methods other than the default, Polygon.ContainsSouthPoleComputer.STD_FXP and Polygon.ContainsSouthPoleComputer.STD_IVOA may not work properly!!
    
    Parameters:
    
    polyVertices - vertices defining the polygon
    
    cspc - method used to defined the inside and the outside of the polygon. So far do not use Polygon.ContainsSouthPoleComputer.STD_FXP and Polygon.ContainsSouthPoleComputer.STD_IVOA.
- Method Detail
  - nVertices
```
public int nVertices()
```
    Returns the number of vertices the polygon contains.
    
    Returns:
    
    the number of vertices the polygon contains.
  - vertex
```
public CooXYZ vertex(int vertexIndex)
```
    Returns the vertex located at the given index in the polygin vertex list.
    
    Parameters:
    
    vertexIndex - index of the vertex we want to access (in [0, nVertices[
    
    Returns:
    
    the vertex located at the given index in the polygin vertex list.
  - contains
```
public boolean contains(CooXYZ p)
```
    Returns true if the polygon contain the point p.
    
    Parameters:
    
    p - point to test
    
    Returns:
    
    true if the polygon contain the point p.
  - intersectSegAB
```
public boolean intersectSegAB(CooXYZ a,
                              CooXYZ b)
```
    Returns true if an edge of the polygone intersects the line defined by the two given points.
    
    Parameters:
    
    a - first segment point
    
    b - second segment point
    
    Returns:
    
    true if an edge of the polygone intersects the line defined by the two given points.

Class Polygon

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Polygon

Polygon

Method Detail

nVertices

vertex

contains

intersectSegAB