Good morning.
Pressing the crouch-button on any chest type with any trapdoor type over it, standing in the trapdoor and trying to move off the chest in any direction will make you fall off. This has been tested on multiplayer servers too.
Trying to crouch off a chest without a trapdoor over it makes it act like a block and wont make you fall off.
My theory is that the trapdoor is trying to push the player off the chest and because the chest has a smaller hitbox, it succeeds.
This bug can be re-created for testing by the images attached with this post.
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migrated
migrated
Please do not mark unreleased versions as affected.
You don't have access to them yet.
Jack McKalling
Also happens on the wide edge of anvils, but not on the narrow edge. So the bug probably happens for any edge that is not aligned to the block grid, not just chests.
Does not happen for glass blocks, which is transparent, so the transparency of the chest has nothing to do with it.
Jack McKalling
Confirmed for 19w02a
Jack McKalling
Confirmed for 19w03a
Jack McKalling
Confirmed for 19w03b
Jack McKalling
Confirmed for 19w03c
migrated
Please make a list of all affected blocks, I did some testing on my own and the chorus flower and plant is the same case, as well as the grindstone, the the fence gate, and the brewingstand. together with these, is also your already pubished affected blocks, the cheast, the ender cheast and the anvil
Jack McKalling
Comfirmed for 19w04a
Jack McKalling
Confirmed for 19w04b and 19w05a
Jack McKalling
Comfirmed for 19w06a
Jack McKalling
Confirmed for 19w07a
Jack McKalling
Confirmed for 19w09a
Jack McKalling
Confirmed for 19w11a
Jack McKalling
Confirmed for 19w11b
Jack McKalling
Confirmed for 19w12a
Jack McKalling
Confirmed for 19w12b
Jack McKalling
Confirmed for 19w13a
Jack McKalling
Confirmed for 19w13b
Jack McKalling
Changed in 19w14a.
It is not possible anymore to be standing inside a trapdoor, as it will force you in the swimming position (even if there is no water around). This can be observed by noticing you fit under the 1-block height, and using the F5 third person camera mode shows the still-standing swimming animation.
Although in this position it is not possible to sneak walk off a chest etc. anymore, this is still bugged. You're not supposed to enter swimming mode on dry land.
muzikbike
Testing discovered MC-147266
Jack McKalling
If you're supposed to be pushed into "swimming" mode by a closing trapdoor, albeit either crawling or swimming, either way, this bug would then not be reproducible anymore.
violine1101
Resolved as "Cannot Reproduce", as it is no longer possible to stand inside of a trapdoor as of 1.14.
migrated
This is actually incorrect for your lower half (I understand crawling is activated with a trapdoor in your head half). In 19w39a (which I assume is carried over from 1.14.4), place a trapdoor on the lower segment of a block, with a solid block underneath. Open the trapdoor so it faces up. Stand in the trapdoor's place. Close the trapdoor. The player does not clip upward above the trapdoor. Walk out of the block: you notice you do not fall the short distance.
You were standing inside of a trapdoor.
as https://twitter.com/henrikkniberg/status/1113084315615793152 explains, the reason for this I suppose is that these crawl checks only occur on the head half, not the feet half. Regardless, the whole process comes across as very hacky and I don't know if Mojang would prefer all these mechanics to remain static forever.
On further investigation, making your feet to stand inside a trapdoor (as described above) prevents another trapdoor above it from triggering crawling. Thus you can be standing inside 2 trapdoors at the same time. Again, just trying to point out that these crawl mechanics are simply not fully grown. Helpful, yes, but not really something to leave alone.