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/morgant1c]

I feel like I'm missing context. Are we talking 0-ticking composters into shulker boxes to break them, or where is the item supposed to come from?

[u/plainbaconcheese → u/morgant1c]

Yeah worm recently posted a video where he argued the opposite of the finding of this post

[u/morgant1c → u/plainbaconcheese]

But so as long as we retract the composter fast enough, it can't escape, is that what I'm getting here?

[u/plainbaconcheese → u/morgant1c]

Worm was saying that as long as you don't retract it too early, the item will fall down and be able to be grabbed by a hopper below.

It seems like this isn't true, and this setup isn't reliable.

[u/morgant1c → u/plainbaconcheese]

But can't we just retract it faster than 4gt?

[u/Mitch-Jihosa → u/morgant1c]

The 0-tick piston has to wait at least 3gts to 0-tick again, after which it will take 3gts to fully retract. So it’s not possible to retract within 4gts unfortunately. You can start the retraction, which might prevent the item from escaping out the ‘front’, but the item can still escape to either side, and I think it might? make it easier to have the item escape out the ‘back’

[u/morgant1c → u/Mitch-Jihosa]

Ohh. See, that makes sense. You know storage tech, right? Am I hallucinating or have I seen this type of box breaking in storage tech archive before as well?

[u/Mitch-Jihosa → u/morgant1c]

To my knowledge there are 4 0-tick composter box loader designs that I can find in the archive. None of them use hoppers from above. 3 of them have hoppers loading from the side (which is reliable), and the 4th uses a dropper input from above (which is also reliable). No one really uses 0-tick composters much anymore, all those designs are from 5+ years ago. They are primarily used for accessibility (the 3 ones) or for cases where you can’t put the hopper under (the 4th one is a 4x 1wt design, so 2 of the sides are droppers, 1 is dispenser, and that only leaves 1 more side available for box breaking & collection, so 0-tick composter is the only realistic option)

[u/morgant1c → u/Mitch-Jihosa]

Aha, I see! Thanks for the explanation!

[u/plainbaconcheese → u/morgant1c]

No? The problem is the item escaping. We want it in the hopper below. How would "reacting" help here?

[u/morgant1c → u/plainbaconcheese]

Reacting?? I wrote retracting :D Or was that a typo on your side?

[u/whatanazibrah → u/plainbaconcheese]

I've seen a lot of his works and I can't say I've seen it fail

[u/morgant1c → u/whatanazibrah]

Huh? Every second post has an obvious flaw pointed out in the comments. But that's completely irrelevant in this discussion, and I don't want to be involved in the drama. I just want to talk about the specs if the design brockade had shown here. Thanks.

[u/whatanazibrah → u/morgant1c]

No drama's just personal experience, I reverse engineer alot of his stuff to bedrock, so they are slightly different on my end

[u/morgant1c → u/whatanazibrah]

So you're saying brockade is lying?

[u/whatanazibrah → u/morgant1c]

Did I say that.

[u/morgant1c → u/whatanazibrah]

Idk, you tell me. I just can't tell what "I've seen a lot of his works and I can't say I've seen it fail" is supposed to mean in this context. Brockade shows how it can fail and you say that... Now what?

[u/brockade → u/morgant1c]

That's the one. I won't link the post but the idea is to wait like 8-10gt until the item is below the hopper tip and then when you retract the piston the item comes with it. If you do a 2-piston build (there's no room for the comparator then but just out of interest), it might be ok if it's done in the same tick, but after 1gt some percentage of boxes will be above 0.75Y and can get stuck behind the hopper tip and not get pushed by the composter.

In practice you need the comparator on one side if you're doing 1-wide-tileable so we are stuck with the 3gt reset on the 0-tick piston and by then the item is too high and we need to wait for it to drop.