extern void object::Guard()
{
    int allyType = Me;                   // put ally category here (i.e. LeggedGrabber)
    int keepCloseDist = 10;              // how far behind to follow
    int parimeterToScan = 50;            // range to look for enemy
	
    object enemy;
	
    while(true)
    {
        enemy = radar(AlienAnt,0,360,0,parimeterToScan);

        if(enemy == null)
            follow(allyType,keepCloseDist);
        else
            moveAndDestroy(enemy);
    }
}

void object::follow(int category, int parimeter)
{
    object ally = radar(category);
	
    float dis = distance(position,ally.position);
	
    if(dis > parimeter)                           // if too far away from ally
    {
        float dif = ally.position.z-position.z;
        float ang = asin(dif/dis);
		
        jet(1-(ang/-20));
		
        float dir = direction(ally.position);
		
        motor(1-dir/22.5,1+dir/22.5);             // move in closer
    }
	
    else                                          // otherwise too close
    { 
        motor(dis/parimeter-1, dis/parimeter-1);  // back up a little
		
        if(topo(position) > 0)                    // if not over water
            jet(-1);                              // then land to conserve energy/minimize heat
    }
}

void object::moveAndDestroy(object target)
{
    float dir;    // direction of target from shooter
    float dis;    // distance of target from shooter
    float dif;    // difference in altitude of target & shooter (relative to sea-level)
    float ang;    // angle shooter must aim (-20 degrees favorable)
	
    dis = distance(position,target.position);
    dif = target.position.z-position.z;
    ang = asin(dif/dis);
	
    jet(1-(ang/-20));                         // thrust until 20 degress above target
	
    dir = direction(target.position); 
	
    motor(1-dir/22.5,1+dir/22.5);             // move towards enemy
	
    dis = distance(position,target.position);   
    dif = target.position.z-position.z;         
    ang = asin(dif/dis);                        
	
    aim(ang);                                 // take aim
	
    dir = direction(target.position);           
	
    if(dis < 30 and dir > -10 and dir < 10)   // if within range
        fire(0.1);
}