Ceiling Hover



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Ceiling Hover is a glitch that makes the player "hover" over a bouncy block (slime, or beds since 1.12) under very specific conditions. The glitch can be performed by jumping under a ceiling such that the block 2.001b below the ceiling has bouncing properties.

Explanation
Whenever the Player collides with a block (ex: ceiling), the game will apply collision physics.

For almost every block, that just means setting the Player's vertical speed to 0.

There is one exception: Slime Blocks (and Beds in 1.12+).


 * If the Player is sneaking, it's treated as a regular collision (Vertical motion is set to 0)
 * Otherwise, it checks if the Player's speed is negative, then inverts it.

Note that nothing would happen if the Player is neither sneaking or moving at negative speed.

In fact, that's exactly what happens with this glitch.

When the game detects a vertical collision, it will consider the block 0.2m under the Player's position to apply collision physics (yes, even for ceiling collisions...)

With a ceiling collision, that generally concerns a block of air. But for ceilings less than 2b tall, the block considered is 1 block lower.

Let's review the steps for the 1.8 Ceiling Hover setup:
 * 1) Jumping under 1.8125bc applies vertical collision with the block on the ground.
 * 2) If the ground block is a slime block, then vertical speed won't be changed, and the Player remains at ceiling level.
 * 3) Repeat step (2) until the Player's speed becomes negative due to gravity.

Note: This glitch happens for 6 ticks, but with Jump Boost it would take even longer. Ceiling Hover can be interrupted at any time by sneaking.

Consequences
This glitch is pretty insignificant: it isn't game-breaking in any way, and requires a very specific setup to perform.