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Zombie game - Help needed for pathfinding

in Programming Questions  •  1 year ago  
Hello everyone, I wonder if anyone would help me with an issues I have regarding pathfinding.

I am making a 2D zombie shooter and I am working on making my zombies separate rather than group together. With a lot of help from a friend (who wrote this section of code) I have now got an algorithm that:

Checks for the nearest zombie
Works out the possible move it can make
Checks to see if there is another zombie in the way
If not then it can move 
If there is, see if you can move on the x axis (and vice versa)

BUT! When the program is run, some of the zombies  will not make the required move, so I have zombies dotted around the screen just not moving - unless I make the player move somewhere else to make the zombie move again.

I don't want to paste the whole program into this post as there is too much of it, but have a look at the above function and you may be able to help!

Copy code
  2. void seekTarget() {
  3.     Mover closestZombie = null;
  4.     float distanceToClosestZombie = 10000;  // arbitrary large number
  5.     float distance;
  6.     int tryX = x;
  7.     int tryY = y;
  8.     // find which of the other zombies is nearest to this one,
  9.     // and what distance separates them
  10.     for (Mover m: movers) {
  11.       if (m == this) {
  12.         // don't compare this zombie to itself!
  13.         continue;
  14.       }
  15.       distance = dist(x, y, m.x, m.y);
  16.       if (distance < distanceToClosestZombie) {
  17.         // the zombie being tested is the closest found yet
  18.         closestZombie = m;
  19.         distanceToClosestZombie = distance;
  20.       }
  21.     }
  22.     
  23.     // work out the "ideal" new x and y coordinates, assuming
  24.     // for now that the closest zombie is not in the way
  25.     // (we'll find that out in a moment)
  26.     
  27.       /*if(targetX > x) {
  28.           tryX++;
  29.           //println("working");
  30.       } else if(targetX < x) {
  31.           tryX--;
  32.           //println("working");
  33.       }
  34.     
  35.       if (targetY > y) {
  36.           tryY++;
  37.           //println("working");
  38.       } else if(targetY < y) {
  39.           tryY--;
  40.           //println("working");
  41.       }*/
  42.       
  43.       if(targetX > player.x) {
  44.         //tryX = tryX + int(zombieSpeed);
  45.         tryX--;
  46.         image(zombieLEFT, tryX, tryY);
  47.         println("working");
  48.       } else if(targetX < player.x) {
  49.         tryX++;
  50.         //tryX = tryX - int(zombieSpeed);
  51.         image(zombieRIGHT, tryX, tryY);
  52.       }
  53.       
  54.       if(targetY > player.y) {
  55.         tryY--;
  56.         //tryY = tryY - int(zombieSpeed);
  57.         image(zombieUP, tryX, tryY);
  58.       } else if(targetY < player.y) {
  59.         tryY++;
  60.         //tryY = tryY + int(zombieSpeed);
  61.         image(zombieDOWN, tryX, tryY);
  62.       }
  63.     
  64.     // if the closest zombie is not already too close, make the
  65.     // ideal move computed above
  66.     if (distanceToClosestZombie > MIN_ZOMBIE_SEPARATION) {
  67.       x = tryX;
  68.       y = tryY;
  69.     }
  70.     
  71.     // otherwise, only make a move that will cause the separation
  72.     // between this zombie and its closest neighbour to either
  73.     // increase or remain the same
  74.     else {
  75.       if (dist(tryX, tryY, closestZombie.x, closestZombie.y) >=
  76.           distanceToClosestZombie) {
  77.         // the ideal move increases or doesn't change the separation
  78.         x = tryX;
  79.         y = tryY;
  80.       }
  81.       else if (dist(tryX, y, closestZombie.x, closestZombie.y) >=
  82.           distanceToClosestZombie) {
  83.         // only the horizontal component of the ideal move increases
  84.         // or doesn't change the separation
  85.         x = tryX;
  86.       }
  87.       else if (dist(x, tryY, closestZombie.x, closestZombie.y) >=
  88.           distanceToClosestZombie) {
  89.         // only the vertical component of the ideal move increases
  90.         // or doesn't change the separation
  91.         y = tryY;
  92.       }
  93.     }
  94.   }
The Mover is the zombie :)

Ah - My mate thinks it is to do with the fact that I also have a move() function separate to this, and that I need to integrate it into the above function, below is the other move() function:

Copy code
  2.  void move() {
  3.     int wouldBeX = x;
  4.     int wouldBeY = y;
  5.     
  6.     //Move along X axis to find player
  7.     if (x < player.x) {
  8.       x++;
  9.       image(zombieRIGHT, x, y);
  10.     } 
  11.     else if (x > player.x) {
  12.       x--;
  13.       image(zombieLEFT, x, y);
  14.     }
  15.     
  16.     //Move along Y axis to find player
  17.     if (y < player.y) {
  18.       y++;
  19.       image(zombieDOWN, x, y);
  20.     } 
  21.     else if (y > player.y) {
  22.       y--;
  23.       image(zombieUP, x, y);
  24.     }

  26.     for (Mover m: movers) {
  27.       //tryToMove(m, wouldBeX, wouldBeY);
  28.     }
  29.   }

Thanks!

Replies(4)

docbones
docbones

Re: Zombie game - Help needed for pathfinding

1 year ago
Hi,

Maybe you can find help with the A* algorythm, designed for pathfinding. Here's a smart introduction :
A* pathfinding for beginners (naturally, "beginner" isn't pejorative, we're all beginners somewhere... ;)

Hope it helps.
Chrisir
Chrisir

Re: Zombie game - Help needed for pathfinding

1 year ago


The Code is too long to read and understand completely

1st Remark

you have
Copy code
  1.       if(targetX > player.x) {
and

Copy code
  1.       } else if(targetX < player.x) {
what if they are the same?
same goes for y...

2nd Remark

Did you test this:
Copy code
  1.       if (m == this) {


3rd Remark

try to enter some random



smiley_face.123
smiley_fa..

Re: Zombie game - Help needed for pathfinding

1 year ago
Thanks Docbones - I have thought about the A* pathfinding algorithm but was told it was far too complicated for what I'm trying to do.

Thanks Chrisir - The likelihood of the zombies possible x & y co-ordinates being the same is really minuscule so I haven't coded for that event. As far as the (m == this) goes, that's just so the zombie doesn't test itself when looking for other zombies that are close to it - cos that would be silly :P And what do you mean "try to enter some random"?

But thank you both for replying - I understand the code is really long for one post but I wasn't really sure on how I could change that and still get my problem across :)
Chrisir
Chrisir

Re: Zombie game - Help needed for pathfinding

1 year ago



As far as the (m == this) goes, that's just so the zombie doesn't test itself

I know - but does it work? Check with println or so.




try to enter some random

that was the idea to have every 5th step or so slightly varied by a random number - so it's a little more random walk / less determinated

see random() in the reference







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