Lower absorption effect with different particle settings / visibility replenishes all hearts of higher amplifier effect

Confirmed for

• 16w38a

Please link to this comment in the description

The following is based on a decompiled version of Minecraft 1.10 using MCP 9.30.

This happens because the method net.minecraft.entity.EntityLivingBase.addPotionEffect(PotionEffect) calls the method net.minecraft.entity.EntityLivingBase.onChangedPotionEffect(PotionEffect, boolean) always with true as second argument, which determines if the attribtues should be re-applied. This should probably be only true if the amplifier of the new applied potion effect is the same or higher than the existing one. The method net.minecraft.potion.PotionEffect.combine(PotionEffect) could be probably changed to return that.

Note: This would mean that a normal golden apple would not add any absoprtion hearts, which might be hard to fix.

Fixed or is blocked by MC-128682.

Seems fixed in 1.13.1.

Pretty weird, I am able to reproduce the bug described here and the one described in MC-128682 in 20w18a, even though they describe the opposite behavior.

It's about time this get fixed. It can seriously ruin PvP fights.

I tested this bug in 1.12.2, 1.13.2, 1.16.1, and 20w30a. The current title (“Absorption replenishes hearts even if effect isn’t actually applied due to lower amplifier”) is accurate for 1.12.2, but it is not accurate for later versions. In the later versions, this effect can not be reproduced using merely an enchanted golden apple and a regular golden apple; commands are required.

Status effects (at least in later versions) contain tags called “Ambient”, “ShowIcon”, and “ShowParticles”. Ambient is used by beacons to make the particles less conspicuous. ShowIcon determines whether or not the icon for the status effects appears in the upper right corner of the screen. ShowParticles determines whether or not the player emits particles from the status effect. The current effects that a player has, including the values of these tags for each effect, can be seen by running

/data get entity @p ActiveEffects

The effect command can not directly specify the values of the Ambient, ShowIcon, and ShowParticles tags for the effect it gives, but it can indirectly specify them via the hideParticles parameter (at the end of the command). Specifying true for the hideParticles parameter cause the ShowIcon and ShowParticles tags to be set to false in the resulting effect. The default values of Ambient, ShowIcon, and ShowParticles (that are used by a golden apple) are false, true, & true, respectively.

In the versions after 1.12.2, the gold hearts of the higher amplifier absorption will only be replenished if at least one of Ambient, ShowIcon, or ShowParticles has a different value between the higher amplifier absorption and the lower amplifier absorption. For example, if you change the commands in the current reproduction steps of this report to have “false” for the hideParticles parameter instead of “true”, then you will not be able to reproduce this bug because the Ambient, ShowIcon, and ShowParticles tags of the absorption given by the command will match the Ambient, ShowIcon, and ShowParticles tags of the absorption given by the golden apple.

Even though the effect command can’t directly specify the values of Ambient, ShowIcon, and ShowParticles, they can be directly specified using custom potions. This allowed me to test each of the 3 tags individually to ensure that this bug can be reproduced using any of the 3 tags. I’ll upload a test world that contains command blocks that give custom potions, in case anyone wants to test this bug for themself.

TL;DR In versions after 1.12.2, this bug can’t occur in a normal survival world. Also, @unknown, the behavior I described above is the reason that you were able to reproduce both MC-88694 and MC-128682 in 20w18a.

Thank you for your detailed analysis! I have updated the report to describe what you mentioned. Please let us know if you think the report could be improved further.

Can confirm in 21w03a.

Can confirm in 21w05b.

Can confirm in 21w06a.

Can confirm in 21w07a.

Video attached.

Can confirm in 1.16.5 and 21w08b.

Can confirm in 21w11a.

Can confirm in 22w14a
pine1needle states that you need to use commands.
Since I believe 1.18 that is no longer the case and using enchanted golden apples and normal apples works again. This means the particle effect does not matter anymore. I would give a code analysis as to why it works now, although I don't have the time, so instead, I will link to a working fix that has an explanation as to how the fix works. FIX

The short reason is just, they run onRemoved & onApplied using the wrong effect strength, and can be easily fixed by just moving around the calls.

I would like to add that this works for all effects in the game, not just absorption. Absorption was the only one noticed due to the golden apples.
Modded Status Effects, new status effects, and absorption are all affected by this bug. Any status effect that does something special in onRemoved or onApplied

An interesting thing to point out:
Marcono1234 said — Note: This would mean that a normal golden apple would not add any absoprtion hearts, which might be hard to fix.
This is actually how it works currently, seems his fix was implemented.

Can confirm in 1.19.