Saturday, September 18, 2021

Bandanas Deflect Zombie Attacks 90% of the Time! (Not anymore - fixed in 41.55)

Edit 2021-10-27: Indie Stone released Project Zomboid build 41.56, and at first look I think they've fixed the bug correctly.  I'll write a post that goes into detail soon.

Edit 2021-09-30: In 41.55 they have "fixed" this bug by changing the code so that falling clothing no longer protects you.  They also adjusted some of the chancetofall rates on some helmets so that they never fall.  They have not fixed the bug that essentially made chancetofall actually represent the chance that the item would stay on.  I've covered this in a new post.

Bandanas are the most OP protective clothing in all Project Zomboid!  They deflect almost 90% of front attacks from a single zombie!

Glasses deflect almost 45% of all front attacks from a single zombie, and you can START with glasses in vanilla Project Zomboid.  That's better than taking the (fixed in 41.54) Thick Skinned trait!

I'll have more examples of the total protection you get from some vanilla Project Zomboid clothing at the end, but let me explain how this works.

I covered head protection in another blog post, and at the time I thought that helmets/hats could only fall off during an attack to the head or neck.  I didn't look carefully enough at the code, because masks and glasses also can fall off, and all of those clothing items can fall off during ANY zombie attack.

When any piece of clothing falls off, that means that a zombie attack hit your character and the falling clothing nullified the attack.  

So at every opportunity, you should wear a hat/helmet, glasses, and a bandana mask.  Each of those has a chance of completely nullifying a zombie attack that would otherwise hit you!


BodyDamage Class

Let's go back to the BodyDamage class to demonstrate how hats/helmets/glasses/bandanas can fall and nullify "successful" zombie attacks:

        if (Rand.Next(100) > n4) {
            n = 1;
            boolean bl4 = false;
            if (this.getParentChar().helmetFall(n3 == BodyPartType.ToIndex(BodyPartType.Neck) || n3 == BodyPartType.ToIndex(BodyPartType.Head))) {
                return false;
            }

In the BodyDamage class, once your character is hit by a zombie attack one of the first things the code does is check getParentChar().helmetFall.

It sends TRUE if the target of the attack was either the neck or head.  In my earlier post, I misinterpreted this to mean that helmetFall was only called if the attack was the neck or head - I was wrong about that.

And you can see here that if helmetFall is true, this method returns false, meaning the attack is nullified and no damage is recorded on your character.


IsoGameCharacter Class

So let's take a closer look at helmetFall, in the IsoGameCharacter class:

    public boolean helmetFall(boolean bl, String string) {
        IsoPlayer isoPlayer = (IsoPlayer)Type.tryCastTo((Object)this, IsoPlayer.class);
        boolean bl2 = false;
        InventoryItem inventoryItem = null;
        IsoZombie isoZombie = (IsoZombie)Type.tryCastTo((Object)this, IsoZombie.class);
        if (isoZombie != null && !isoZombie.isUsingWornItems()) {
	    // Code skipped because this is only for Zombies
        } else if (this.getWornItems() != null && !this.getWornItems().isEmpty()) {
            for (int i = 0; i < this.getWornItems().size(); ++i) {
                WornItem wornItem = this.getWornItems().get(i);
                InventoryItem inventoryItem3 = wornItem.getItem();
                String string2 = wornItem.getLocation();
                if (!(inventoryItem3 instanceof Clothing)) continue;
                int n = ((Clothing)inventoryItem3).getChanceToFall();
                if (bl) {
                    n += 40;
                }
                if (inventoryItem3.getType().equals(string)) {
                    n = 100;
                }
                if (((Clothing)inventoryItem3).getChanceToFall() <= 0 || Rand.Next((int)100) < n) continue;
                IsoFallingClothing isoFallingClothing = new IsoFallingClothing(this.getCell(), this.getX(), this.getY(), PZMath.min((float)(this.getZ() + 0.4f), (float)((float)((int)this.getZ()) + 0.95f)), Rand.Next((float)-0.2f, (float)0.2f), Rand.Next((float)-0.2f, (float)0.2f), inventoryItem3);

Remember that bl was TRUE if the target was the head or neck.  But even attacks on other body parts make it to this part of the code (with bl set to FALSE).

We skip over some code because it only applies to zombies.  Maybe I'll go over that in another post.  It actually doesn't protect the zombies as much from attacks.

Then we go through every piece of clothing worn by the character.  This includes every piece of clothing, not just helmets and hats.

We skip the code if it isn't a piece of clothing, and continue to the next piece of clothing.

Then we get the ChanceToFall, and call that n.

(As an example, let's look at the Bandana Mask, which has a chance to fall of 5 - at the end of this entry I have a list of all vanilla items that can fall, with their ChanceToFall value).

Here we see bl used.  If the target was the head or neck, bl is true, and n is increased by 40 (to 45 for our example).

And then there is the decision line - if a random d100 roll is less than n (45 if the target was the head/neck, 5 otherwise), then we continue.  Continue means we go back and look at the next item of clothing in the list - nothing happens, and we go to the next piece of clothing worn by the character.

And if we get past the d100 check, the clothing falls.  In the Bandana example, this means that Bandanas stay on 5% of the time, and when the target is the head or neck they stay on 45% of the time.

As I've reported before, this is a bug.  If the Bandana Mask should have the low 5% chance of falling, not staying on.  So this line should read Rand.Next((int)100>= n.


How Much Protection Is This?

In my last post, I calculated that a single zombie attacking from the front targets the neck 6.4% of the time, and the head or neck 12.7% of the time.  There's a little rounding there, so I'm just going to use the slightly more accurate figure of 6.36% for head hits (and neck hits) in this example.

Bandanas (as a mask or on your head) have a ChanceToFall of 5, meaning there is a 55% chance to fall from a head/neck attack, and a 95% chance to fall for other body parts.  If a head is targeted 6.36% of the time and the neck is targeted 6.36% of the time, then all other body parts together are targeted 87.28% of the time.

  • Head/Neck:  55% chance to fall * 12.72 chance of being targeted
  • Other: 95% chance to fall * 87.28% chance of being targeted
Total Protection:  89.912%

Glasses have a ChanceToFall of 50.

Total Protection = 10% * .1272 + 50% * .8728 = 44.912%

Reflective Ski Glasses (and Safety Goggles and some other eyewear) have a ChanceToFall of 20.

Total Protection = 40% * .1272 + 80% * .8728 = 71.312%

Baseball Caps (and Tinfoil Hats) have a ChanceToFall of 80, so the protection isn't great.  If you are hit in the head or neck while wearing them, they never fall off.  Plus they don't have any bite or scratch protection.  Still they, are better than nothing because when other parts of your body are hit, they might fall off.  Plus, you can start with them.

Total Protection = 20% * .8728 = 17.456%

Calculating the protection from items like the Riot Helmet was a little more complicated, because even when they don't fall off of your head they offer 100% protection to the head, so that modifies the protection a little.  I ran some items through my spreadsheet (with slightly more accurate numbers):

  • Riot Helmet - 96.52% Total Protection
  • Football Helmet - 94.65% Total Protection
  • Military Helmet - 88.01% Total Protection
  • Hard Hat or Firefighter Helmet - 78.73% Total Protection

Also remember that these values combine if you are wearing more than one.

If you are wearing a head bandana + a bandana mask + regular glasses, the total protection is actually

1 - (1-0.89912) * (1-0.89912) * (1-0.44912) = 99.44%!

If you start with a baseball cap + regular glasses, you get to start with a protection value of

1 - (1-0.17456) * (1-0.44912) = 54.53%!

 

Comments On the Bug

So one of the reasons this is such a big deal is because of the bug I mentioned.  Things that should stay on almost all the time are falling off, and items that should fall easily are staying on.  

I suspect that Indie Stone will rework this mechanic a little more than just fixing the specific bug I mentioned.  If they ONLY fix my bug, baseball caps will become pretty OP, falling off 100% of the time the head or neck is attacked, and 80% of the time other body parts are attacked.  But at least baseball caps are supposed to be fairly easy to fall off in real life.  Bugged Football Helmets fall off to 57% of head/neck attacks, and 97% to other attacks.

Whatever work they do to this part of the code, I'll cover it when it changes.  I suspect glasses will still be worth wearing, even if they aren't as powerful as they are now. 


Vanilla Items That Can Fall

Here's a list of vanilla items that can fall, and the base % chance that they will fall.  Remember, while this bug still exists, it is actually the base % chance that they won't fall.  For the best benefit right now, pick items with a low percentage.  Once the bug is fixed, I'll update this blog post and tell everyone to pick items with a high percentage chance of falling.

Military Helmet                       10
Bandana (Head)                         5
Baseball Cap                          80
KY Baseball Cap                       80
Baseball Cap                          80
Army Baseball Cap                     80
Kentucky Baseball Helmet              10
Riverside Rangers Baseball Helmet     10
Z Hurricanes Baseball Helmet          10
Beanie Hat                            40
Beret                                 80
Army Beret                            80
Bicycle Helmet                        20
Chef Hat                              80
Cowboy Hat                            80
Crash Helmet                          10
Motorcycle Helmet                      3
Police Motorcycle Helmet              10
USA Crash Helmet                      10
Ear Muffs                             80
Ear Protectors                        80
Fast Food Server Hat                  80
Ice Cream Server Hat                  80
Spiffo's Server Hat                   80
Fedora                                80
Black Band Fedora                     80
Firefighter Helmet                    20
Football Helmet                        3
Tartan Golf Cap                       80
Golf Cap                              80
Hard Hat                              20
Mining Helmet                         20
Hockey Helmet                         10
Jockey Helmet - 1                     10
Jockey Helmet - 2                     10
Jockey Helmet - 3                     10
Jockey Helmet - 4                     10
Jockey Helmet - 5                     10
Jockey Helmet - 6                     10
Police Trooper Hat                    70
Police Deputy Hat                     70
Raccoon Hat                           30
Ranger Hat                            70
Riding Helmet                         10
Riot Helmet                            1
Santa Hat                             80
Green Santa Hat                       80
Shower Cap                            80
Airforce Helmet                       10
Spiffo Suit Head                      10
Summer Hat                            80
Medical Cap                           80
Sweatband                             50
Wedding Veil                          80
Welder Mask                           30
Winter Hat                            40
Woolly Hat                            40
Bucket Hat                            80
Bonnie Hat                            80
Visor                                 80
Peaked Army Cap                       80
Bandana (Tied)                         5
Bandana (Face)                         5
Newspaper Hat                         80
Party Hat with Stars                  80
Coloured Party Hat                    80
Tin Foil Hat                          80
Hockey Goalie Mask                    30

Reflective Ski Sunglasses             20
Aviator Glasses                       50
Glasses                               50
Reading Glasses                       50
Safety Goggles                        20
Shooting Glasses                      20
Ski Goggles                           20
Sunglasses                            50
Swimming Goggles                      30

Although Riot Helmets, Football Helmets, and Motorcycle Helmets fall more easily than the bandana, they already offered 100% protection to the head, so I don't consider them as OP as bandanas.


Thanks for reading!  If you see any mistakes, or if you have a question you'd like me to answer, let me know in the comments!

No comments:

Post a Comment

Do Gloves Protect You From Broken Glass?

Yes, gloves protect you from handling broken glass - any pair of gloves.  But gloves are not needed when removing broken glass from a smashe...