ucar.unidata.gis
Class SpatialGrid

java.lang.Object
  ucar.unidata.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).

Version:

$Id: SpatialGrid.java,v 1.14 2005/05/13 18:29:33 jeffmc Exp $

Author:

caron, with design help from russ

Constructor Summary

SpatialGrid(int nx, int ny)
Constructor

Method Summary

void	clear() clear all the grid cells
Object	findClosest(Point2D pt) Find the closest marked cell to the given point
boolean	markIfClear(Rectangle2D rect, Object o) Check if the given rect intersects an already drawn one.
void	print() print the grid
void	setGrid(Rectangle2D bbox, Rectangle2D cellSize) 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 columns

ny - maximum number of grid rows

Method Detail

setGrid

public void setGrid(Rectangle2D bbox,
                    Rectangle2D cellSize)

Set the grid scale.

Parameters:

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

cellSize - divide the bounding box into cells of this size. 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

print

public void print()

print the grid

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

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