Difference between revisions of "Circular Targeting"

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== See also ==
 
== See also ==
  
* [[Circular Targeting/Walkthrough]] An in-depth example of creating a Circular Targeting algorithm in Robocode, courtesy of  [[Dummy]].
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* [[Circular Targeting/Walkthrough]] - An in-depth example of creating a circular targeting algorithm in Robocode, authored by [[Dummy]].
* [[CodeSnippets/Nano Circular Linear Predictor | NanoBot sized Circular Targeting example code]]
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* [[CodeSnippets/Nano Circular Linear Predictor | NanoBot sized circular targeting example code]]
 
* Alisdair Owen's [http://www-106.ibm.com/developerworks/library/j-circular/ circular targeting tutorial] with iteration.
 
* Alisdair Owen's [http://www-106.ibm.com/developerworks/library/j-circular/ circular targeting tutorial] with iteration.
  

Revision as of 16:33, 13 November 2007

Description

A method of targeting which assumes that the target will continue moving with the same turn rate and at the same speed.

Example

This is the code used in WaveSurfing Challenge Bot C:

//Add import robocode.util.* for Utils and import java.awt.geom.* for Point2D
//This code goes in your onScannedRobot() event handler

double bulletPower = Math.min(3.0,getEnergy());
double myX = getX();
double myY = getY();
double absoluteBearing = getHeadingRadians() + e.getBearingRadians();
double enemyX = getX() + e.getDistance() * Math.sin(absoluteBearing);
double enemyY = getY() + e.getDistance() * Math.cos(absoluteBearing);
double enemyHeading = e.getHeadingRadians();
double enemyHeadingChange = enemyHeading - oldEnemyHeading;
double enemyVelocity = e.getVelocity();
oldEnemyHeading = enemyHeading;

double deltaTime = 0;
double battleFieldHeight = getBattleFieldHeight(), 
       battleFieldWidth = getBattleFieldWidth();
double predictedX = enemyX, predictedY = enemyY;
while((++deltaTime) * (20.0 - 3.0 * bulletPower) < 
      Point2D.Double.distance(myX, myY, predictedX, predictedY)){		
	predictedX += Math.sin(enemyHeading) * enemyVelocity;
	predictedY += Math.cos(enemyHeading) * enemyVelocity;
	enemyHeading += enemyHeadingChange;
	if(	predictedX < 18.0 
		|| predictedY < 18.0
		|| predictedX > battleFieldWidth - 18.0
		|| predictedY > battleFieldHeight - 18.0){

		predictedX = Math.min(Math.max(18.0, predictedX), 
		    battleFieldWidth - 18.0);	
		predictedY = Math.min(Math.max(18.0, predictedY), 
		    battleFieldHeight - 18.0);
		break;
	}
}
double theta = Utils.normalAbsoluteAngle(Math.atan2(
    predictedX - getX(), predictedY - getY()));

setTurnRadarRightRadians(Utils.normalRelativeAngle(
    absoluteBearing - getRadarHeadingRadians()));
setTurnGunRightRadians(Utils.normalRelativeAngle(
    theta - getGunHeadingRadians()));
fire(3);

See also