Robocode tutorial 7 - Radar locking

In this tutorial , We're going to write such a code , It will keep the enemy from escaping our eyes . Radar locking is the basis of an efficient combat robot , because robot Only execute onScannedRobot Method , We can get information about the enemy , and onScannedRobot The method will only be called after our radar scans the enemy , Of course , The procedure called is automatic .

Radar is a ray centered on a robot , In order to be more intuitive , We'd better turn on the radar graphic display , The method is ：

Get into robocode, open Options-> Preferences->viewoptions, Check Visible Scan Arcs

 

Remember ours Enemy Class? ？ It plays a vital role in our robot . So if you're not familiar with it class Enemy You'd better go and have a look first .

stay Enemy There is one in the class direction Variable , Its value is ：

direction= bearingRadian+ me.getHeadingRadians();

As this picture shows , I understand direction Variable , Radar locking is simple .

The radar scan is actually a line , When the scan line reaches the target , Trigger onScannedRobot event , Update current data , Include direction. When the program is executed to onScannedRobot Code in , The angle of the radar scan line getRadarHeadingRadians() Has been and direction Deviate from . In order to lock the target , We can scan the radar in the opposite direction . Because the radar rotates very fast , and getRadarHeadingRadians() and direction The offset of is not large , Robots are of a certain size . So the scanning line sweeps back and forth on the target , Radar locking is realized .

 

public voidonScannedRobot(ScannedRobotEvent e) {

       enemy.update(e,this);

       doubleOffset = rectify( enemy.direction-getRadarHeadingRadians() );

     setTurnRadarRightRadians( Offset * 1.5);

}

This is ours onScannedRobot Method ,enemy.updata(e,this); Is to call our enemy Methods in objects , Update enemy information , Of course , Forget a little , before this , We need to generate a enemy object , The specific method is ：

Enemy enemy = new Enemy();

Let's explain here rectify Method , Its function is to correct the angle , because direction Minus the orientation of our radar , It may be greater than 180 Degrees or less -180 degree , For example, when it is greater than 180 When the degree of , The angle of rotation we need is not that big , Just turn the direction by an angle . This rectify It's easy , When applied a lot later . Its code is ：

   public  double rectify ( doubleangle )

   {

        if ( angle < -Math.PI )

            angle += 2*Math.PI;

        if ( angle > Math.PI )

            angle -= 2*Math.PI;

        return angle;

}

In the code ,enemy.direction -getRadarHeadingRadians() Is the offset that the radar needs to rotate . Suppose the radar scans clockwise before , that enemy.direction slightly smaller than getRadarHeadingRadians(), Negative . the rectify() After the method is corrected, it is the value to be rotated . And then use setTurnRadarRightRadians Rotating radar , The degree of rotation is offset 1.5 times , because RadarOffset Negative , So scan in the opposite direction , Ensure that whatever the goal

How to move , The scan line is always on the target . above 1.5 You can change to 2,3 Equal number . When you are in Options Open in Visible Scan Arcs After the options , You can see the Green fan , The multiple is 1.5 When , Like a line , And the multiple is 2,3 You can see that it looks like a fan .

In addition, let's talk about two other pieces of code ：

       setAdjustGunForRobotTurn( true );

       setAdjustRadarForGunTurn( true );

Their function is to make the radar 、 artillery 、 Body movement is independent , Specific reference API manual .

 

At this point, our radar scanning code is completed , Run and try our “ Observer ” Well ！！

 

attach ： Observer complete code ：

 

package cm;

import java.awt.*;

import robocode.*; 

 

public class ObserverRobo  extends AdvancedRobot

{

   Enemy enemy= newEnemy();

   public static double PI = Math.PI;

       

   public void run()

   {

      setAdjustGunForRobotTurn(true);

        setAdjustRadarForGunTurn( true );

        this.setColors(Color.red, Color.blue, Color.yellow, Color.black, Color.green);

       

      while(true){

         if(enemy.name == null){

            setTurnRadarRightRadians(2*PI);

            execute();

         }

         else{

            execute();

         }

      }

   }

       

   public void onScannedRobot(ScannedRobotEvent e)

   {

      enemy.update(e,this);

        double Offset = rectify( enemy.direction -getRadarHeadingRadians() );

        setTurnRadarRightRadians( Offset *1.5);

   }

 // Angle correction method , important

   public  double rectify ( doubleangle )

   {

        if ( angle < -Math.PI )

            angle += 2*Math.PI;

        if ( angle > Math.PI )

            angle -= 2*Math.PI;

        return angle;

   }

   public class Enemy {

      public double x,y;

      public String name = null;

      public double headingRadian = 0.0D;

        public double bearingRadian = 0.0D;

        public double distance = 1000D;

        public double direction = 0.0D;

        public double velocity = 0.0D;

        public double prevHeadingRadian = 0.0D;

        public double energy = 100.0D;

       

       

        public void update(ScannedRobotEvent e,AdvancedRobotme){

          name = e.getName();

          headingRadian =e.getHeadingRadians();

          bearingRadian = e.getBearingRadians();

          this.energy = e.getEnergy();

          this.velocity = e.getVelocity();

          this.distance = e.getDistance();

          direction = bearingRadian +me.getHeadingRadians();

          x = me.getX() + Math.sin( direction ) * distance;

          y=  me.getY() + Math.cos( direction ) * distance;     

        }

   }

}