Package ucar.nc2.ui.gis

Class SpatialGrid

java.lang.Object

ucar.nc2.ui.gis.SpatialGrid

public class SpatialGrid
extends Object

Fast implementation for tracking data overlap and closest point in a 2D region. The region of interest is divided into non-overlapping cells. Each cell may contain zero or one data objects. This allows quickly finding if a data object may be drawn (markIfClear) and closest drawn object to a point (findClosest).

Constructor Summary

Constructors

Constructor	Description
SpatialGrid(int nx, int ny)	Constructor

Method Summary

Modifier and Type	Method	Description
void	clear()	clear all the grid cells
Object	findClosest(Point2D pt)	Find the closest marked cell to the given point
Object	findIntersection(Point2D p)	Check if the given point is contained in already drawn object
Object	findIntersection(Rectangle2D rect)	Check if the given rect intersects an already drawn object
boolean	markIfClear(Rectangle2D rect, Object o)	Check if the given rect intersects an already drawn one.
void	setGrid(Rectangle2D bbox, double width, double height)	Set the grid scale.
void	setOverlap(int overlap)	Set how much the data may overlap.

Methods inherited from class java.lang.Object

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

Constructor Detail

SpatialGrid

public SpatialGrid(int nx,
                   int ny)

Constructor

Parameters:

nx - maximum number of grid cells in x

ny - : maximum number of grid cells in y

Method Detail

setGrid

public void setGrid(Rectangle2D bbox,
                    double width,
                    double height)

Set the grid scale.

Parameters:

bbox - bounding box: we are only interested in points inside of this

width - : divide the bounding box into cells of this width.

height - : divide the bounding box into cells of this height. maximum number of grid cells is nx x ny

setOverlap

public void setOverlap(int overlap)

Set how much the data may overlap.

Parameters:

overlap - : percent overlap

clear

public void clear()

clear all the grid cells

markIfClear

public boolean markIfClear(Rectangle2D rect,
                           Object o)

Check if the given rect intersects an already drawn one. If not, set the corresponding cell as marked, store object, return true, meaning "ok to draw".

Parameters:

rect - the bounding box of the thing we want to draw

o - store this object

Returns:

true if inside the bounding box and no intersection

findIntersection

public Object findIntersection(Rectangle2D rect)

Check if the given rect intersects an already drawn object

Parameters:

rect - the bounding box of the thing we want to draw

Returns:

object that intersects, or null if no intersection

findIntersection

public Object findIntersection(Point2D p)

Check if the given point is contained in already drawn object

Parameters:

p - the point to check

Returns:

object that intersects, or null if no intersection

findClosest

public Object findClosest(Point2D pt)

Find the closest marked cell to the given point

Parameters:

pt - find the closest marked cell to this point

Returns:

the object associated with the closest cell, or null if none