/***
 * TinyEdgeFollower
 * is a LeJOS robot that follows the edge of a black/white line.
 * 
 * This code is a stripped-down version of what's in 
 * the JimsRobot directory, to show that there's more than one way
 * to do it, and to give you an example of a less object-oriented style.
 *
 * To use it
 *    You'll need a robot with 2 motors (on ports A,B)
 *    and one light sensor (on port S3).
 *    Compile and download the code as usual:
 *      lejosc TinyEdgeFollower.java
 *    The turn on lego brick, aim at IR tower.
 *      lejos TinyEdgeFollower
 * 
 *    Put the robot over the white color, and push "Run".
 *    When it beeps, move it to the black color.
 *    It should then follow the border.
 *
 * @version 1.0 Oct 25 2002
 * @author Jim Mahoney
 *
 ****/
import josx.platform.rcx.*;

class TinyEdgeFollower {

    public static int whiteValue;
    public static int blackValue;

    public static void main(String[] args) throws Exception {
	initialize();

	TextLCD.print("Wh");
	Thread.sleep(1000);
	whiteValue = Sensor.S3.readValue();	// define white value.
	Sound.beep();

	TextLCD.print("Bl");
	Thread.sleep(2000);
	blackValue = Sensor.S3.readValue();	// define black value.
	Sound.beep();

	TextLCD.print("--");

	while (true){

	    int howFarFromWhite = Math.abs(Sensor.S3.readValue()-whiteValue);
	    int howFarFromBlack = Math.abs(Sensor.S3.readValue()-blackValue);

	    if ( howFarFromWhite < howFarFromBlack ){
		Motor.A.backward();
		Motor.B.stop();
	    }
	    else {
		Motor.A.stop();
		Motor.B.forward();
	    }
	    Thread.sleep(50);  // to avoid too much jiggling.

	} // end while
    } // end main

    public static void initialize(){
	Sensor.S3.setTypeAndMode(SensorConstants.SENSOR_TYPE_LIGHT,
				 SensorConstants.SENSOR_MODE_PCT);
	Sensor.S3.activate();
	Motor.A.setPower(7);
	Motor.B.setPower(7);
    }

}