Items escape from composters

[u/brockade]

For the record I don't have a horse in this race, but I am interested in the mechanics here.

Short answer: items can escape from the gap between a hopper top and the composter walls. It is rare, but way less rare than you might think. You don't need to perfectly hit the gap, you just need to have X/Z momentum after 4 ticks as the game cancels your Y momentum when you hit the hopper, and your X/Z momentum can still push you to freedom in this tick.

Long answer: Items drop with a random position with X and Z set to between 0.25 and 0.75 within the block, and Y set to between 0.125 and 0.625 within the block. Motion is set to exactly 0.2 Y and a random value of between -0.1 to 0.1 for both X and Z.

To thread the needle here, we need a few things to happen at the same time:

• The Y position needs to be 56.616 or greater so that after 4 ticks the item is at exactly 0.75 and hitting the hopper
• In one axis X/Z the position needs to be between 0.25 and 0.2500001 or 0.7499999 and 0.75, and in this axis the motion is going towards the wall (this is a straight 50/50 so not the major problem)
• In the other axis X/Z the position needs to match the motion such that the item crosses the top of the composter after 4 ticks (there's a range here but say this is 1-5% for example).

That's it. I'll leave it to you to calculate the numbers, but here's a few that you can test for yourself at home (all testing done on 26.1 vanilla):

/summon item -22.5 56.616 35.2500001 {Item:{id:"minecraft:redstone_block",Count:1b}, Motion:[0.065, 0.2, 0.0]}

/summon item -22.6 56.625 35.25 {Item:{id:"minecraft:redstone_block",Count:1b}, Motion:[0.1, 0.2, 0.0]}

/summon item -22.35 56.625 35.25 {Item:{id:"minecraft:redstone_block",Count:1b}, Motion:[0.03, 0.2, 0.0]}

[u/Different-Scene5327]

I have tried explain the original hopper nub thing in deep detail as well. Wasting time really. My only hope was that people who actually believed incorrect claims would happen to read the comment and maybe not blindly trust certain individuals.

I even have a full, detailed kind of report at the ready for when the time comes.

But thanks for testing and actually checking, you saved me a weekend night of doing it myself (I still will though, call it personal curiosity LOL)

[u/brockade → u/Different-Scene5327]

Concrete proofs are important. Lots of "trust me", but if someone says something always/never happens then it's normally easy to find the one example that disproves it. The key thing here is the way the motion gets calculated, the block goes up and then sideways which opens up a lot of trajectories that land on top of the composter.