I want to implement code where a zombie chases after a person but I don't want the image for the actor rotate because it looks weird. A solution would be appreciated. Thanks!
Billkingtang wrote ...
2022/3/31
How do I move without rotating my actor?
I figured it out but now I have another question. I want my zombie to chase people of the parent class but zombie is included within it too. The parent class "Pedestrian" has 3 sublasses "Citizen", "Police", and "Zombie." I want the zombie to search for the either the nearest citizen or police. Right now in the code it only searches for the closest Citizen. Help would be appreciated!
private void targetClosestHuman()
{
int dist = 400;
Actor closest = null;
if(!getObjectsInRange(dist, Citizen.class).isEmpty())
{
for (Object obj: getObjectsInRange(dist, Citizen.class))
{
Actor guy = (Actor) obj;
int guyDist = (int)Math.hypot(guy.getX() - getX(), guy.getY() - getY());
if (closest == null || guyDist< dist)
{
closest = guy;
dist = guyDist;
}
}
turnTowards(closest.getX(),closest.getY());
}
}
I think the easiest is to get a list with the Pedestrian class. In the for-loop, ignore actors which are Zombies using “instanceof”.
I'm not sure what instanceOf is and how to use it properly
if (obj instanceof Zombie) continue; //rest of for-loop
It worked thanks so much!!!!!!
These are two separate parts of the same class where the error occured.
Im not sure why but after a bit from running I run into a error.
java.lang.NullPointerException
at Zombie.targetClosestHuman(Zombie.java:105)
at Zombie.act(Zombie.java:48)
at greenfoot.core.Simulation.actActor(Simulation.java:567)
at greenfoot.core.Simulation.runOneLoop(Simulation.java:530)
at greenfoot.core.Simulation.runContent(Simulation.java:193)
at greenfoot.core.Simulation.run(Simulation.java:183)
public void act()
{
if (hp > 0){ //if zombie has more then 0 hp it will remain active
hp -= VehicleWorld.ZOMBIE_DEATH_RATE;
hpBar.update(hp);
//Move
targetClosestHuman();
}else if(getY() < 100){
getWorld().removeObject(this);
}else if ( getY() > 550){
getWorld().removeObject(this);
}else{ //dies when it reaches 0 hp
getWorld().removeObject(this);
}
} private void targetClosestHuman()
{
int dist = 100;
Actor closest = null;
if(!getObjectsInRange(dist, Pedestrian.class).isEmpty())
{
for (Object obj: getObjectsInRange(dist, Pedestrian.class))
{
if (obj instanceof Zombie) continue; // loops through all actors in Pedestrian class and ignores all Zombies
Actor guy = (Actor) obj;
int guyDist = (int)Math.hypot(guy.getX() - getX(), guy.getY() - getY());
if (closest == null || guyDist < dist)
{
closest = guy;
dist = guyDist;
}
}
//So my actor doesnt appear to rotate when he moves after a human
setRotation(rotation); //Before turning and moving it is set to 0
move(maxSpeed); //Move
//After turning and moving
turnTowards(closest.getX(),closest.getY()); //Turn
rotation = getRotation(); //Get Rotation and do the turn
setRotation(0); //Set the Rotation back to 0
}
}The problem looks like it stems from the if (obj instanceof Zombie) continue; If I remove that then I dont run into the problem. Is there any possible solutions? I think the problem is when there are no pedestrians nearby the loop doesn't know what to do?
EDIT: I found a solution to the problem. I simply used a conditional to check if the obj was null.
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