The bug
I shot a regular arrow on the ground and reloaded my world, the arrow now has particles as if it's a tipped arrow, yet when I pick up the arrow it gives a regular arrow.
Code analysis
Based on 1.11.2 decompiled using MCP 9.35 rc1
The Color tag is only written if the arrow has a custom color. The problem is that the game calls the method net.minecraft.entity.projectile.EntityTippedArrow.refreshColor() when an arrow without Color tag is loaded. This method sets the color to the water color.
This could be fixed by always writing the Color tag to make sure tipped water arrows keep their particles as well. Additionally the check if the Color tag exists when reading the NBT data can be removed then.
Linked issues
is duplicated by 41
MC-107969
No gravity arrows
Resolved
MC-111533
Arrow has water potion when summoned or updated
Resolved
MC-111730
Arrows turn into potion arrows with no effect when unloaded
Resolved
MC-111804
Normal arrows look into arrows of water breathing after relogging
Resolved
MC-112036
Arrows with NoAI tag gain a blue particle effect
Resolved
relates to 3
Attachments
Comments 23
Back in 16w50a. Possibly related to MC-108943.
Easy fix to summon arrow with no particles!!!
summon arrow ~ ~ ~ {Color:-1}
If you set the color value to -1 the particles are invisible, no worries anymore 😃
They can fix this bug by giving it that value as default
There's a more specific bit of code at the root of this bug. (Basing this off the source of 1.12.2.) When writing an arrow entity to NBT (i.e. on save or when modifying the data), it only writes the color tag if its fixedColor property is true. This property is only set in the setFixedColor and refreshColor methods, the latter of which sets the color to the default blue. This means that for normal arrows, it's false by default, and will never be written to NBT data; so when it reloads, the color tag isn't there, and it's refreshed to blue.
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The fix to this is quite simple, and requires only two small changes. In the tipped arrow entity's setPotionEffect method, instead of setting the color directly on the data manager, it should call setFixedColor to do this, which will then set the boolean flag properly and allow -1 to be written with the arrow's NBT, fixing the issue for bow-fired arrows.
The second change is to fix the issue for dispenser-fired arrows. In the registerDispenserBehaviors method of the Bootstrap class, when it registers the arrow behaviors for normal arrows, it just needs to call entitytippedarrow.setFixedColor(-1) somewhere between creating the entity and returning it. (The method is currently private, as is the flag, so this would need to actually call a new setter or just make the setFixedColor method public.)
Those small changes should fix this long-standing bug for good 🙂
Erik Broes
Simply summoning an arrow also gives it particules, and without having to reload the world.