Solved How Could I Change an Entity's Walking Speed?

Hi, I need help with changing the walking speed of an entity. Not a player's, but perhaps a chicken or zombie or something. Could anybody help me with that? I'm lost.

 

If you're spawning a custom entity, use
getAttributeInstance(GenericAttributes.MOVEMENT_SPEED).setValue();

If not, just give them a speed potion or something

 

@Scimiguy I wouldn't like to use any potion effects, just the code. Do you know how I could do so when any entity is hit?

Code:

@EventHandler
    public void onEntityDamage(EntityDamageByEntityEvent event) {
        if (!(event.getDamager() instanceof Arrow)) return;
        Arrow arrow = (Arrow) event.getDamager();
        if (arrow.getShooter() instanceof Player) {
            // half walking speed of entity
        }
    }

This is my code so far.

 

https://bukkit.org/threads/tutorial-setting-entity-attributes.158065/
Disclaimer: There is a high chance, that your plugin will break with this technique

 

@mcdorli I don't know how I could import this, but I will try.

EDIT: I tried to, and this is what I've come up with.

Code:

private static final UUID movementSpeedUID = UUID.fromString("206a89dc-ae78-4c4d-b42c-3b31db3f5a7c");
   
    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
    public void onEntityDamage(EntityDamageByEntityEvent event) {
        LivingEntity entity = (LivingEntity) event.getEntity();
       
        if (!(event.getDamager() instanceof Arrow)) return;
        Arrow arrow = (Arrow) event.getDamager();
        if (arrow.getShooter() instanceof Player) {
            EntityInsentient nmsEntity = (EntityInsentient) ((CraftLivingEntity) entity).getHandle();
            AttributeInstance attributes = nmsEntity.getAttributeInstance(GenericAttributes.MOVEMENT_SPEED);
           
            AttributeModifier modifier = new AttributeModifier(movementSpeedUID, "movement speed multiplier", 1.0d, 1);
           
            attributes.b(modifier);
        }
    }

To be quite honest, I do not completely understand the code, although, the entities do go very fast when I hit them.

Could you explain to me how I could divide their original speed by half? Also, I don't want this to be a "spoonfeed," so if you wouldn't mind, could you also explain to me what this all means? Or anybody?

 

If ypu want to set the speed to half, set the third argument to 0.5 and the forth to 1. All this does, is changes things inside the entity's class. Read more about nms if you really want to understand it

 

@mcdorli I tried that, but the entity still goes faster!

 

Some things
You shouldn't use MONITOR priority, except for logger plugins. They shouldn't change anything on the server.
Try setting the fourth parameter to 0, what happens?

 

@mcdorli They go even faster!

 

Try to set it something very low, like 0.01 (not 0) do they go slower? And the fourth to 1

 

@mcdorli I did actually try that before you said to, and it did make them go slower, but I still don't know what the default is.

 

Then experiment

 

If you're looking for the default movement speed of base mobs (not spiders), then I already did the work for you for my PowerMobs plugin:

0.23000000417232513
@Xenthos @mcdorli

 

That's a very interesting number, I'm certain you would get kind of the same thing with 0.23

 

@mcdorli
Possibly, but that's the exact default number, so if you want accuracy, just put that in

 

You got that from trial and error, or did you looked up the github page?

 

@mcdorli
There's a github page?
Link?

 

@Scimiguy So I'll put 0.11500000208 for the third argument, but what about for the fourth?

 

For nms amd bukkit, I troed to use ot tp check for different packet constructor, but it isn't a big help, becaise of the weird variable names
https://github.com/Bukkit/mc-dev/tree/master/net/minecraft/server
Here's the bukkit one
https://github.com/Bukkit/Bukkit

Probably 1

 

Mine has been testing and confirmed.
The number I gave you is the absolute correct for at least Minecraft 1.8

Just use mne as a reference so you can easily change it later.

So when you're setting your attribute, just put in
0.23000000417232513*0.5

or something.
That way you always know how fast you're going in reference to default when you look at your code.

 

@Scimiguy @mcdorli Okay, so I put 1 for the fourth arg, but I can't tell the difference in speed between an entity that has been shot and an entity that hasn't.

EDIT: I'm getting an error! I'll find it and show you guys

 

Then the best way would be probably to use the .setValue() scimiguy mentioned above. Just put ot right after you're getting the movement speed attribute, and delete everything abput the modifier

 

@mcdorli @Scimiguy This is the error for my code:

Code:

ould not pass event EntityDamageByEntityEvent to Test v1.0
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:310) ~[spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.callEvent(CraftEventFactory.java:87) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.callEntityDamageEvent(CraftEventFactory.java:553) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.handleEntityDamageEvent(CraftEventFactory.java:466) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.handleLivingEntityDamageEvent(CraftEventFactory.java:585) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.EntityLiving.d(EntityLiving.java:1102) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.EntityLiving.damageEntity(EntityLiving.java:743) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.EntityMonster.damageEntity(EntityMonster.java:42) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.EntityZombie.damageEntity(EntityZombie.java:167) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.EntityArrow.t_(EntityArrow.java:242) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.World.entityJoinedWorld(World.java:1607) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.World.g(World.java:1582) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.World.tickEntities(World.java:1425) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.WorldServer.tickEntities(WorldServer.java:597) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:786) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot.jar:git-Spigot-5f38d38-18fbb24]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_65]
Caused by: java.lang.IllegalArgumentException: Modifier is already applied on this attribute!
    at net.minecraft.server.v1_8_R3.AttributeModifiable.b(SourceFile:87) ~[spigot.jar:git-Spigot-5f38d38-18fbb24]
    at me.xenthos.main.ListenerClass.onEntityDamage(ListenerClass.java:34) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_65]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_65]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_65]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_65]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot.jar:git-Spigot-5f38d38-18fbb24]
    ... 21 more

 

You still apply the modofier, delette ot, ypu don't need anything after setting the value of the generic attribute

 

@mcdorli SOLVED. Thank you!