Problem with reading arrow NBT, also weird entity behavior.

[theishiopian]

I'm trying to get the potion effect attached to a tipped arrow upon impact, but I'm running into two weird, possibly related issues. The first is that all arrows, tipped are not, turn into tipped arrows when fired, with regular arrows giving off blue particles. Second, the nbt tag is completely blank when I read it. 

 

Code:

https://pastebin.com/9ezTvh70

[V0idWa1k3r]

17 minutes ago, theishiopian said:

The first is that all arrows, tipped are not, turn into tipped arrows when fired, with regular arrows giving off blue particles.

https://bugs.mojang.com/browse/MC-107941

 

18 minutes ago, theishiopian said:

Second, the nbt tag is completely blank when I read it. 

You are doing everything you could do completely wrong. First of all Entity#readEntityFromNBT deserializes the entity in question from the NBT provided. The NBT won't change, since the entity is reading from it, not writing into it. Finally you don't need to mess with NBT at all. Check if the arrow is an instance of EntityTippedArrow(hint: you are already doing it), cast it to one and obtain the potion effect from said arrow. Use reflection if you have to.

[theishiopian]

I tried using reflection initially, but it didnt work when the mod was built.

Additionally, when checking whether the arrow is an instance of EntityTippedArrow, it always returns true, regardless of whether the arrow is tipped or not.

[Cadiboo]

6 minutes ago, theishiopian said:

I tried using reflection initially, but it didnt work when the mod was built.

Additionally, when checking whether the arrow is an instance of EntityTippedArrow, it always returns true, regardless of whether the arrow is tipped or not.

use ReflectionHelper

[V0idWa1k3r]

7 minutes ago, theishiopian said:

I tried using reflection initially, but it didnt work when the mod was built.

Then you likely didn't provide the SRG name. Minecraft is obfuscated. It means that the field/class/method names in the compiled game differ from those in the source code. Use ReflectionHelper - it gives you methods which take multiple names for the thing you are searching for. Provide both the MCP(deobfuscated) name and SRG(obfuscated-ish). It's actually a bit more complex(there are three levels of names, Notch, SRG, MCP), you can ask for more if you'd like to know more. You can get the SRG names from mcpbot or from %user_folder%\.gradle\caches\minecraft\de\oceanlabs\mcp\mcp_snapshot\%snapshot_data%\%game_version%\srgs

 

11 minutes ago, theishiopian said:

Additionally, when checking whether the arrow is an instance of EntityTippedArrow, it always returns true, regardless of whether the arrow is tipped or not.

It's because technically all arrows apart from spectral ones are TippedArrows.

[theishiopian]

net/minecraft/entity/EntityAreaEffectCloud.func_184484_a(Lnet/minecraft/potion/PotionType;)V=|p_184484_1_

is this the one for the potion type field? Forgive my noobishness, this is a lot to take in at once.

[V0idWa1k3r]

4 minutes ago, theishiopian said:

is this the one for the potion type field?

No, it's not and you can see that yourself:

• It's called func_XXXXX. Why would a field be named func?
• It's owner class is net/minecraft/entity/EntityAreaEffectCloud. AreaEffectCloud != EntityTippedArrow

[theishiopian]

ok, well what does a field look like in here? all there are are inits and funcs.

[V0idWa1k3r]

5 minutes ago, theishiopian said:

ok, well what does a field look like in here?

field_XXXXX. The line will also start with the letters FD(FielD) For example, the ones you are interested in:

FD: net/minecraft/entity/projectile/EntityTippedArrow/potion net/minecraft/entity/projectile/EntityTippedArrow/field_184560_g
FD: net/minecraft/entity/projectile/EntityTippedArrow/customPotionEffects net/minecraft/entity/projectile/EntityTippedArrow/field_184561_h

 

[theishiopian]

Theres nothing in the srg.exc that looks like that. Am I looking in the wrong place?

EDIT: looks like I need to look in the srg files themselves. I feel like a moron now.

Edited November 25, 2018 by theishiopian
Im dum

[theishiopian]

Question regarding ReflectionHelper.findField: the method doesnt seem to take an obfuscated name. Do I put it in the top anyways? It looked like it could take multiple names.

[V0idWa1k3r]

ReflectionHelper.findField takes in a class and an array of field names. That array contains all names to look up the field by. That would be the MCP and the SRG names.

[theishiopian]

Ok, that makes a lot more sense. Just searching it by potion didnt work, as expected, so i'll try the mcp names and srgs and such. Thank you for being so patient with me, this is very informative.

[theishiopian]

ok, using both the obfuscated name and de-obfuscated name works perfectly. Thank you so much!