Page 286 - The Definitive Guide to Building Java Robots

Preston_5564C07.fm Page 267 Monday, September 26, 2005 5:38 AM

CHAPTER 7 ■ NAVIGATION 267

which the robot might want to navigate. The fourth field is an int[] called characteristic. This
field represents the four coordinate axes as they would be measured in this region. The array
{1,0,0,1} would represent readings in the north and west direction, but not long or out-of-range
readings in east and south.
The region has a constructor of a name and a size. In the constructor, I also add the center
waypoint since it will be needed later for navigation.
Outside of standard getter and accessor methods, I have three methods, one that will get
the point in the region by name, and two other methods that do point translations. The method
getScaledPoint() converts points taken in this region, say, from a sonar to a scaled point in the
region within the bounds of 100 × 100. The method getScaledMagnitude() converts the final
distance vector back to actual inches for any movement. See Example 7-16.

Example 7-16. Region.java
package com.scottpreston.javarobot.chapter7;

import java.awt.Point;
import java.util.ArrayList;

public class Region extends Vertex{

//list of way points in center
private ArrayList wayPoints = new ArrayList();
// start point in region absolute coordinates
private int size = 0;
// used to determine position within region N,E,S,W readings
private int[] characteristic = new int[]{0,0,0,0};

// constructor
public Region(String name, int size) {
super(name);
this.size = size;
// just add center point for later use.
addWayPoint(NavPoint.CENTER_POINT,50,50);
}

// navigation points
public void addWayPoint(NavPoint p) {
wayPoints.add(p);
}
public void addWayPoint(String name,int x, int y) {
addWayPoint(new NavPoint(name,x,y));
}