Uploaded March 2023 | Updated September 2026, 1 week ago
Just a video showing a small observation I made today. Simply put, there's some slight but noticeable differences in how jumping into a ceiling works across versions. By "jumping into a ceiling" I just mean the setup shown in the video, where I'm not under a ceiling on one tick, but then on the next tick I try to jump up into one. Interestingly, this differs from
In 1.7.10 and prior, you just jump upwards into the side of the block, without ever colliding vertically with the ceiling.
In 1.8 you do the opposite, not hitting the side of the block at all and instead colliding with the ceiling, moving you underneath it. You also get unconditionally snapped downwards a bit though, which briefly clips you into the ground.
In 1.8.1 you collide the same way as 1.8, but instead of being unconditionally snapped 0.6m downwards, you just get snapped downwards to the floor level that you jumped from.
In 1.14 this was changed again. You still collide with the ceiling like in 1.8.1, but instead of being snapped to ground level, you actually rise up to the ceiling.
I could be wrong, but I assume these discrepancies are just an indirect result of stepping logic(thing that lets you climb slabs/stairs) changing over the versions. If you weren't aware, entities that use their hitbox for collision don't move along a straight line from one position to the next. Instead they move along each axis independently, checking collision along the way. This is why you can seemingly clip through corners if you take them at a less direct angle. You don't actually, you just end up moving around it within the tick. Anyway, in this order of operations vertical movement always gets handled first. This is why prior to 1.8 you just jump straight upwards into the side of the block. It first processes your vertical movement, moving you upwards, and then processes your horizontal movement, which collides with the side of the block, since you're now in the air.
This is actually what made me notice these differences, since I expected the same thing to happen in modern versions. But, in 1.8, Mojang altered the stepping logic to fix MC-3337. To do this they made you consider ceilings that you were moving towards instead of just the ones you were directly under. But I guess in doing so they forgot the ground existed, and so snap you quite far down from where the ceiling was(which is usually in the ground).
I guess in 1.8.1 they decided to remember that floors exist, and so instead of snapping you into the ground, they just snap you directly to the ground. Still kind of weird in the context of jumping into a ceiling since it just negates your vertical movement, but at least you don't get sucked into the ground.
I think the last change to this was then in 1.14, where they again changed stepping. Now instead of snapping you to the ground, you can actually move upwards. This is still how it works now as far as I know, where you jump up into the ceiling and bonk on it.
Initially I just thought there was one difference(1.7.10 vs modern), but when I tried to find the exact version it changed I realized there was quite the evolution, and figured I'd document it.
Just a video showing a small observation I made today. Simply put, there's some slight but noticeable differences in how jumping into a ceiling works across versions. By "jumping into a ceiling" I just mean the setup shown in the video, where I'm not under a ceiling on one tick, but then on the next tick I try to jump up into one. Interestingly, this differs from
In 1.7.10 and prior, you just jump upwards into the side of the block, without ever colliding vertically with the ceiling.
In 1.8 you do the opposite, not hitting the side of the block at all and instead colliding with the ceiling, moving you underneath it. You also get unconditionally snapped downwards a bit though, which briefly clips you into the ground.
In 1.8.1 you collide the same way as 1.8, but instead of being unconditionally snapped 0.6m downwards, you just get snapped downwards to the floor level that you jumped from.
In 1.14 this was changed again. You still collide with the ceiling like in 1.8.1, but instead of being snapped to ground level, you actually rise up to the ceiling.
I could be wrong, but I assume these discrepancies are just an indirect result of stepping logic(thing that lets you climb slabs/stairs) changing over the versions. If you weren't aware, entities that use their hitbox for collision don't move along a straight line from one position to the next. Instead they move along each axis independently, checking collision along the way. This is why you can seemingly clip through corners if you take them at a less direct angle. You don't actually, you just end up moving around it within the tick. Anyway, in this order of operations vertical movement always gets handled first. This is why prior to 1.8 you just jump straight upwards into the side of the block. It first processes your vertical movement, moving you upwards, and then processes your horizontal movement, which collides with the side of the block, since you're now in the air.
This is actually what made me notice these differences, since I expected the same thing to happen in modern versions. But, in 1.8, Mojang altered the stepping logic to fix MC-3337. To do this they made you consider ceilings that you were moving towards instead of just the ones you were directly under. But I guess in doing so they forgot the ground existed, and so snap you quite far down from where the ceiling was(which is usually in the ground).
I guess in 1.8.1 they decided to remember that floors exist, and so instead of snapping you into the ground, they just snap you directly to the ground. Still kind of weird in the context of jumping into a ceiling since it just negates your vertical movement, but at least you don't get sucked into the ground.
I think the last change to this was then in 1.14, where they again changed stepping. Now instead of snapping you to the ground, you can actually move upwards. This is still how it works now as far as I know, where you jump up into the ceiling and bonk on it.
Initially I just thought there was one difference(1.7.10 vs modern), but when I tried to find the exact version it changed I realized there was quite the evolution, and figured I'd document it.
