I'm playing around with custom spawners for a combat arena in an adventure map. I noticed that my mobs drop items they have equipped, even if their respective drop chance is set to 0.
I've added the schematics file for a mob spawner, of which the mobs are affected by this issue.
The mob spawned is a PigZombie wearing a pumpkin on its head and a torch with fire aspect 2 in its hand.
They also have a healing potion in their chest slot with dropchance 0.6, which can't be seen. All the other dropchances are 0.
Two potion effects have been applied: weakness and invisibility.
I've seen them drop the healing potions, as intended, but the enchanted torch as well.
I've seen them drop their pumpkin when I started messing around with the spawner, but not (yet?) in the version I've attached.
Other info:
I did not notice this in the 1.4.3 PRE.
Mob command
/summon bat ~ ~1 ~ {NoAI:1b,ArmorItems:[{id:"stone",Count:1b},{id:"dirt",Count:1b},{id:"grass_block",Count:1b},{id:"glass",Count:1b}],HandItems:[{id:"white_wool",Count:1b},{}],ArmorDropChances:[0f,0f,0f,0f],HandDropChances:[0f,0f]}Looting command
/give @p minecraft:stick{Enchantments:[{id:sharpness,lvl:32767},{id:looting,lvl:32767}]}Code analysis by @unknown can be found in this comment.
As of 1.11, this affects Vex swords, since they have a HandDropChance of 0 on the mainhand.
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Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
Confirmed for
1.8.4
Used commands
/summon Bat ~ ~1 ~ {NoAI:1,Equipment:[{id:stone,Count:1},{id:dirt,Count:1},{id:grass,Count:1},{id:glass,Count:1},{id:wool,Count:1}],DropChances:[0f,0f,0f,0f,0f]}
/give @p stick 1 0 {ench:[{id:16,lvl:32767},{id:21,lvl:32767}]}Confirmed for
16w05b
Please add these commands
Mob command
/summon Bat ~ ~1 ~ {NoAI:1b,ArmorItems:[{id:"stone",Count:1b},{id:"dirt",Count:1b},{id:"grass",Count:1b},{id:"glass",Count:1b}],HandItems:[{id:"wool",Count:1b},{}],ArmorDropChances:[0f,0f,0f,0f],HandDropChances:[0f,0f]}Looting command
/give @p stick 1 0 {ench:[{id:16,lvl:32767},{id:21,lvl:32767}]}Please link to this comment in the description
The following is based on decompiled version of Minecraft 1.9 using MCP 9.24 beta. All method and class names are the names used in the decompiled version.
The reason why this happens is because the method net.minecraft.entity.EntityLiving.dropEquipment(boolean, int) is only testing if this.rand.nextFloat() - (float)lootingModifier * 0.01F) < d0 (d0 being the drop chance). This means if the looting enchantment is 100 or higher, items will be dropped.
Edit: As said in MC-114715 this calculation defeats the purpose of really rare drops, for example 0.000001% suddenly becomes 1.000001%. It might be better to solve this by multiplying the randomly generated value.
It may happen with a looting enchantment :
this.rand.nextFloat() - (float)par2 * 0.01F < this.equipmentDropChances[var3]
par2 is the looting bonus coefficient, so the item can be drop.
If you want to be sure that the item wont spawn : set the drop chance to -2.
(The issue work as intended)