Walking on blocks less than 1 block tall placed on ice, slime blocks or honey blocks acts like walking on ice, slime block or honey blocks directly

This may or may not be a bug and either way it probably shouldn't be fixed given the number of uses that have come up for this feature since the reintroduction of silk touch on ice. Just like BUD switches it would be rather unfortunate to have this removed.

I don't know what uses sciguyryan is talking about. All I know is that when I built a slab-road across an icy lake, I slip around on the slabs. I think this should be fixed.

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Ice speedways. Plain and simple. They are a good feature.

This was a single-player game.
Logging out/back in did not help.
Closing the program and restarting it did not help.
I have been able to reproduce this in 1.4.4. I have not tried it in the 1.4.5 pre-release.

Also, it is possible to slide as if you were on ice when standing on the edge of a half-slab next to ice. (see screenshot)

@Anon Ymus:
Can confirm this for Minecraft 1.4.5 when sneaking on slabs next to ice blocks.

Why did you have to post this? It is awesome for making ice runs

I reported it because it's a bug. It's entirely up to Mojang if they fix this bug or turn it into a feature.
To make ice runs, you can just use ice blocks without slabs too, it makes no difference.

See MC-12834 for the code that causes this to happen and a fix.

Actually, while I agree this probably shouldn't be possible, it does make a difference to put something above it. I've seen people put trap doors above ice to create smaller space. When jumping rapidly while sprinting through it, you go even faster than just having ice. Just pointing that out.

Louis: that rapid jumping behavior with trapdoors was fixed around 1.4 I think. I had a parkour type map that used it and had to update it to remove that particular jump.

Confirmed for 14w21b

guys give up already... this has been in the game since 1.4.2 and it's nearly 1.8 already. i think mojang have unofficially decided to keep this in. perhaps we will see confirmation some time soon.

"Open" and "Closed: Won't Fix" aren't the same thing.

Confirmed for 14w27b

Confirmed for 14w29b

Confirmed for 14w30a, 14w30b, 14w30c

Please do not mark unreleased versions as affected. You do not have access to this yet.

Still an issue in 14w32a

Still an issue in 1.8-pre1 and 1.8-pre2

Still an issue in Minecraft 1.8-pre3 and 1.8

Still an issue in Minecraft 1.8.1

Still an issue in 15w31a, 15w31b

Still in 15w38a and below

Still in 15w42a and below

Original reporter is inactive, giving ticket to @unknown.

Thanks. Will take care of this ticket.

Confirmed for 15w43c.

Confirmed in 15w47c. In addition to ice & slimeblocks, packed ice will also cause strange behavior.

Relates to MC-1133. In fact, they are basically the same bug. The game calculates effects based simply on the block below the player's center, not what they are actually standing on.

Resolved MC-1133 to this ticket.

I would argue that they are slightly different; MC-1133 is about x/z position while this ticket is about vertical position. The two don't always occur at the same time and I think it is conceivable that one could be fixed while the other stays the same.

While there could be 2 different fixes, they are both caused by the same basic issue. It would probably make more sense to combine them, then if one is fixed without the other just reopen the one that wasn't fixed.

They are NOT caused by the same basic issue. This one is caused by the incorrect order of operations (floor, then -1, rather than -1, then ceil). That issue is caused by the use of a single point check rather than checking all four corners of the player's hitbox.

I guess there's multiple ways these problems can be looked at (and fixed). Reopening.

Probably Intended

No, it's not, else this would've been resolved back during 1.4 development, give me 1 reason why this would bs intended

Confirmed for 15w49a

This bug was affected minecraft version 1.0.0 or older.

@unknown: The tracker wasn't available untill 1.4, older versions cannot be added as they don't exist on the tracker and onlycurrent versions can be selected
Also 1.0.0 is outdated

Confirmed for 1.9-pre3

Confirmed for 1.9.1-pre3.

Confirmed for 1.9.3-pre3.

Confirmed for 1.9.4.

Confirmed for 16w20a.

Confirmed for 16w21a.

Confirmed for 16w21b.

Confirmed for 1.10-pre1.

Confirmed for 1.10-pre2.

Confirmed for 1.10.1.

Confirmed for 1.10.2.

Confirmed for 17w17b

Confirmed for 1.12-pre5.

Can confirm for 1.12.1.

Affects 18w16a

Can confirm in 1.13-pre3.

Affect 1.13.1

Affects 18w46a

Affects 18w47a and 18w47b

Affects 18w48a

Affects 18w48b, can I request ownership of the ticket?

Affects 18w49a

Affects 18w50a

I think this bug is actually kind of a feature, because you can use it so widely e.g. for superspeed sprinting tunnels through the nether. It would be a shame if this gets fixed, even though it makes no sense that you could slip on half slabs if there is ice under them.

Affects 1.14.3

Occurs on Farmland and Grass Path as well.

related to MC-1133

Should be 'won't fix' in my opinion. This bug allows greater player creativity since you can place slabs on ice rather than having ice itself aid in ice based speed tunnels. Doesn't allow for anything more, and is a quirk that adds to the possibilities in the game.

Wow, took you guys a veeery loooong time to decide this is WAI. But still, good to know this is a feature now 🙂

According to MC-163952 this is no longer WAI but FIXED instead, at least for the case of soulsand and ice (MC-6451)

Considering you don't even have physical contact with those blocks yet their properties (which rely on physical contact) still apply, it's a no-brainer that it was a bug to begin with. The only reason I can see for this being intended is if the code is set to detect a player in the block space above those blocks, as opposed to being physically on top of the block itself. In that sense the code would be working exactly as it was designed to, despite it not being an intuitive or reasonable design.

I included the relevant code way back in 2013 (I have no reason to believe that it has substantially changed since). The code floors the player's position values to integers, then subtracts 1 from Y. This works fine if the player is standing anywhere within the XY bounds of the block, and directly on top of it, but as soon as the player is any amount above the block (including jumping and flying) the results change.

I at the time suggested subtracting 1/16th (instead of 1), then flooring, which will always result in the same block if the player is walking on top of a half slab or similar, and would also work for carpets (which are 1/16th thick). Using a smaller value (eg. epsilon) further minimizes the amount above the block could be and get the wrong block (although there are few blocks in Minecraft that do not have size deltas less than 1/16th, only a pressure plate (depressed) does, but it doesn't have collision).