com.bbn.openmap.omGraphics.util
Class RibbonMaker

java.lang.Object
  com.bbn.openmap.omGraphics.util.RibbonMaker

public class RibbonMaker
extends java.lang.Object

The RibbonMaker class takes polygon coordinates and creates another polygon from it, a buffer region based on ground distance, around the original poly. It assumes that the polygon coordinates are going in a clockwise direction. The returned polygon is actually an OMAreaList made up of OMPolys, OMArcs and OMLines, depending on the shape of the original polygon.

The RibbonMaker is created from one of the factory methods that designates whether the coordinates are radians or decimal degrees. FYI - OMPoly coordinates retrieved from the getLatLonArray method are in radians. After the RibbonMaker is created, call the method that creates the appropriate shape. For now, getOuterRing is your only option. To use:

 
 llPoints = new double[] { 40.0f, -92.0f, 42.0f, -87.0f, 38.57, -90.825, 37.0f, -89.0f, 35.0f, -94.0f, 40.0f,
                -92.0f };
 
 OMGraphic omg = RibbonMaker.createFromDecimalDegrees(llPoints).getOuterRing(Length.MILE.toRadians(100));
 
 

Author:

ddietrick

Field Summary

protected static int	BENDS_LEFT
protected static int	BENDS_RIGHT
protected double	bufferLimit
protected GeoArray	geoCoords
protected GeoArray	geoCoords_reversed
protected static int	STRAIGHT

Constructor Summary

protected

RibbonMaker(GeoArray gCoords)

Method Summary

protected void	addPolyForIntersection(OMPoly poly1, OMPoly poly2, double dist, OMAreaList ret) Called to handle BENDS_LEFT, concave corners.
protected void	addShortLegPolyForIntersection(Geo g1, Geo g2, Geo g3, int ribbonSide, double dist, OMAreaList ret) Called when it's known that one of the legs between the corner is smaller than the buffer depth.
protected int	bends(Geo g1, Geo g2, Geo g3) Method that determines which way the angle between the three points bends.
static RibbonMaker	createFromDecimalDegrees(double[] coords) Create a RibbonMaker from decimal degree coordinates.
static RibbonMaker	createFromRadians(double[] coords) Create a RibbonMaker from radian coordinates.
OMGraphic	getArc(Geo gc, OMPoly poly1, OMPoly poly2) Given two polylines, with the end point of poly1 being the same distance from a point as the starting point of poly2, create an arc that connects them.
protected OMPoly	getHalfPoly(RibbonIterator rIterator, int side, boolean first) Given a RibbonIterator created from two Geos, create a poly from half of that buffer path.
protected OMPoly	getOMPolyFromGeos(java.util.List<Geo> geos) Converts Vector of Geos to an OMPoly with linetype great_circle.
OMAreaList	getOuterRing(double dist) Assumes coords represent a polygon, returns an OMAreaList representing buffer zone around the outside of a polygon.
protected OMPoly	getPoly(RibbonIterator rIterator, int side) Given a RibbonIterator created from two Geos, create a poly from that buffer path.
protected Geo	getPolyIntersection(OMPoly poly1, OMPoly poly2) Just return the point where the two polygons cross.
protected OMGraphic	getPushbackPoly(OMPoly omp, double dist) Takes a poly that's going to be added to the buffer and removes any points that may be too close to the original poly.
protected void	handlePointsForOuterRing(Geo g1, Geo g2, Geo g3, double dist, OMAreaList ret) Takes a corner represented by the three geos, and adds OMGraphics to the OMAreaList depending on which way the corner bends - for right turns, it'll add an OMLine, OMArc and OMLine.
protected boolean	tooClose(Geo pnt, double distance) Checks to see if a point is too close to any side of the original polygon.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

geoCoords

protected GeoArray geoCoords

geoCoords_reversed

protected GeoArray geoCoords_reversed

STRAIGHT

protected static final int STRAIGHT

See Also:

Constant Field Values

BENDS_LEFT

protected static final int BENDS_LEFT

See Also:

Constant Field Values

BENDS_RIGHT

protected static final int BENDS_RIGHT

See Also:

Constant Field Values

bufferLimit

protected double bufferLimit

Constructor Detail

RibbonMaker

protected RibbonMaker(GeoArray gCoords)

Method Detail

createFromDecimalDegrees

public static RibbonMaker createFromDecimalDegrees(double[] coords)

Create a RibbonMaker from decimal degree coordinates.

Parameters:

coords - lat,lon,lat,lon in decimal degrees.

Returns:

RibbonMaker

createFromRadians

public static RibbonMaker createFromRadians(double[] coords)

Create a RibbonMaker from radian coordinates.

Parameters:

coords - lat,lon,lat,lon in radians.

Returns:

RibbonMaker

getOuterRing

public OMAreaList getOuterRing(double dist)

Assumes coords represent a polygon, returns an OMAreaList representing buffer zone around the outside of a polygon.

Parameters:

dist - distance of buffer area, in radians. Use Length to convert.

Returns:

OMAreaList of a polygon that is a distance away from the coordinate polygon's edges.

handlePointsForOuterRing

protected void handlePointsForOuterRing(Geo g1,
                                        Geo g2,
                                        Geo g3,
                                        double dist,
                                        OMAreaList ret)

Takes a corner represented by the three geos, and adds OMGraphics to the OMAreaList depending on which way the corner bends - for right turns, it'll add an OMLine, OMArc and OMLine. The OMLines will go from half the distance of the legs to the rounded corner. The left turn will have a polygon added.

Parameters:

g1 - point 1

g2 - point 2

g3 - point 3

dist - buffer distance in radians

ret - OMAreaList to add OMGraphics to.

bends

protected int bends(Geo g1,
                    Geo g2,
                    Geo g3)

Method that determines which way the angle between the three points bends.

Parameters:

g1 -

g2 -

g3 -

Returns:

STRAIGHT if no bend, BENDS_LEFT if bends less than PI, BENDS_RIGHT if bends more than PI.

tooClose

protected boolean tooClose(Geo pnt,
                           double distance)

Checks to see if a point is too close to any side of the original polygon.

Parameters:

pnt -

distance -

Returns:

true if is too close and should not be added to the buffer polygon.

getPushbackPoly

protected OMGraphic getPushbackPoly(OMPoly omp,
                                    double dist)

Takes a poly that's going to be added to the buffer and removes any points that may be too close to the original poly.

Parameters:

omp - the buffer poly to be added later

dist - the distance all points should be from the original

Returns:

the OMGraphic with good points.

addShortLegPolyForIntersection

protected void addShortLegPolyForIntersection(Geo g1,
                                              Geo g2,
                                              Geo g3,
                                              int ribbonSide,
                                              double dist,
                                              OMAreaList ret)

Called when it's known that one of the legs between the corner is smaller than the buffer depth. Does some extra work to figure out what points should be added to the buffer.

Parameters:

g1 - point 1

g2 - point 2, the corner

g3 - point 3

ribbonSide - which side of the ribbon should be calculated.

dist - the distance the buffer should be from the legs

ret - the OMGraphicList to add the resulting poly to.

getPolyIntersection

protected Geo getPolyIntersection(OMPoly poly1,
                                  OMPoly poly2)

Just return the point where the two polygons cross.

Parameters:

poly1 -

poly2 -

Returns:

null if no point found.

getOMPolyFromGeos

protected OMPoly getOMPolyFromGeos(java.util.List<Geo> geos)

Converts Vector of Geos to an OMPoly with linetype great_circle. Assumes that the List has valid coordinates on it. Does not do a closeness check to the original poly, expected that's been done.

Parameters:

geos - a set of coordinates

Returns:

OMPoly

addPolyForIntersection

protected void addPolyForIntersection(OMPoly poly1,
                                      OMPoly poly2,
                                      double dist,
                                      OMAreaList ret)

Called to handle BENDS_LEFT, concave corners. RuntimeException is thrown when one of the legs is much shorter than the other and the mid-point is still in the buffer of one of the legs. In that special case, the intersection point is not found.

Parameters:

poly1 -

poly2 -

ret -

getHalfPoly

protected OMPoly getHalfPoly(RibbonIterator rIterator,
                             int side,
                             boolean first)

Given a RibbonIterator created from two Geos, create a poly from half of that buffer path. Points are not checked for closeness to original poly.

Parameters:

rIterator - RibbonIterator for one of the legs of corner

side - which RibbonIterator side

first - which half you want, true for first part

Returns:

OMPoly that represents half of the buffered path.

getPoly

protected OMPoly getPoly(RibbonIterator rIterator,
                         int side)

Given a RibbonIterator created from two Geos, create a poly from that buffer path.

Parameters:

rIterator - RibbonIterator for one of the legs of corner

side - which RibbonIterator side

Returns:

OMPoly that represents buffered path between geos.

getArc

public OMGraphic getArc(Geo gc,
                        OMPoly poly1,
                        OMPoly poly2)

Given two polylines, with the end point of poly1 being the same distance from a point as the starting point of poly2, create an arc that connects them.

Parameters:

gc - point

poly1 - polyline where the last end point is used

poly2 - polyline where the first end point is used.

Returns:

OMArc