Ceiling Hover/zh

在 1.8 中，这是唯一可用于执行天悬停的设置 (1.8125bc 下面有史莱姆)

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

解释

每当玩家与一个方块（地板或天花板）垂直碰撞时，游戏将应用碰撞物理。

对于几乎每个方块，这只是意味着将玩家的垂直速度设置为 0。

/* in class Block */
public void onVerticalCollision(Entity entityIn)
{
    entityIn.motionY = 0.0D;
}

但有一个例外：粘液块（和 1.12+ 中的床）。

/* in class BlockSlime */
public void onVerticalCollision(Entity entityIn)
{
    if (entityIn.isSneaking())
        super.onVerticalCollision(entityIn);
    else if (entityIn.motionY < 0.0D)
        entityIn.motionY = -entityIn.motionY;
}

• 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 somehow moving at a positive speed (and not sneaking).

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 (even for ceiling collisions...)

Let's review the steps for the 1.8125bc Ceiling Hover setup:

1. Jumping under 1.8125bc applies vertical collision with the block 0.2m below the player (at ground level).
2. If that block is a slime block, then vertical speed won't be set to 0, and the player remains suspended under the ceiling.
3. Repeat step (2) until the player's vertical speed becomes negative due to gravity.

Note: This glitch happens for a few ticks, but with Jump Boost it would take 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 very specific setups to be made use of.