Blip/ja

Blipとは、通常とは異なる高さに着地することで、より高くジャンプできる仕組みである.

Steppingが落下中に適用されることで発生する.

1.8では3種類のblipがある:


 * 「通常のBlip」: 壁際に着地することでブロックの側面に乗り上げられるもの（仕様）.
 * Blip-Up: 低い壁の真横に着地することで、判定を悪用し空中に着地できるもの.
 * Wall Blip: 天井付きのX方向の壁の横に着地するもの（blip-upと同じ効果）.

Blip-Up
https://youtu.be/BjNbUP5-4wo

プレイヤーの着地時、ゲームは壁の当たり判定をチェックし、プレイヤーが周囲の壁に上れるかを確認する. この時、通常のsteppingと同じ処理が行われる.


 * プレイヤーのバウンディングボックスをリセットする
 * バウンディングボックスを上に動かす（最大0.6b）
 * バウンディングボックスを水平方向に動かす（X→Z）
 * バウンディングボックスを下に動かす（最大0.6b）

この手順は、プレイヤーが低い障害物を乗り越えられるようにする目的がある. しかし、steppingの適用が、バウンディングボックスがtick開始時のプレイヤーの位置にリセットされた後に行われるという致命的な欠陥がある. tick開始時のプレイヤーの位置が空中だった場合、stepping手順の開始は本来あるべき位置よりも高い位置で行われてしまう. この時、プレイヤーのバウンディングボックスは十分に下がりきらず、空中で停止してしまうことがある. こうして発生するバグはBlip-Upと呼ばれる.

このバグにより、プレイヤーは地面よりも上に「着地」できるため、通常よりも高くジャンプできる.

必要条件:

 * （落下/ジャンプで）垂直方向の速度がマイナスなこと
 * 比較的低い壁（カーペット/スイレンの葉など）の真横に着地すること - 着地判定tickのプレイヤーの位置よりも低い必要がある.

セットアップ:
blip-upのセットアップ時の原則は、開始地点からの低い方の地面と高い方の地面のtierを同じにすること.
 * blip-upの効果は、一般的に落下速度が速いほど大きくなる.
 * 着地判定tickでのプレイヤーと地面の距離ができるだけ大きくなるよう慎重に調整する必要がある.
 * 得られる高さは0bから3.92b（終端速度）の間. 壁が高いほど、セットアップの効果は小さくなる.

シンプルなセットアップの例:
 * +1.5bのセットアップ
 * +1.75bのセットアップ

Wall Blip
Wall Blips were discovered much later than Blip-Ups, due to the precise setup and conditions they require.

This blip variant happen due to the same quirks of the code concerning collisions, but are trickier to understand and perform.

https://youtu.be/vueSpP-P53U

The role of the wall is to trigger the stepping mechanic (even though the wall itself cannot be stepped onto) The role of the ceiling is to redirect the player in a different route, in an attempt to exploit the "best of 2 routes" procedure.

必要条件:

 * The ceiling must be at least 1.8b above the ground, and at most 0.6b above the player's head on the landing tick.
 * The wall must be X-facing (in order to direct the initial route inside the hole)
 * The player must have position and velocity such that the redirected route goes further horizontally than the initial route.

This last requirement is a bit confusing, so let's illustrate it with a diagram and formula:



On the landing tick, if $(v_X,v_Z)$ is the player's velocity, and $(\delta_X,\delta_Z)$  is the offset between the player and the corner of the wall, the requirement is:

$$\sqrt{\delta_X^2 + v_Z^2} > \sqrt{v_X^2 + \delta_Z^2}$$

連続Blip


Blip-Ups and Wall Blips can be performed repeatedly on the same setup to gain more and more height.

This trick cannot be stacked to reach unlimited heights: eventually, the player is high enough that the jump takes one more tick to land, thereby losing most of the height gained.

連続Blip-Up
Each consecutive blip-up adds an extra 0.104 height, with occasional height losses every 1-4 jumps.


 * You can only blip once on 3 snow layers (4px) -> +0.104
 * You can chain up to 2 blips on a trapdoor (3px) -> +0.208
 * You can chain up to 3 blips on a carpet* (1px) -> +0.312
 * You can chain up to 4 blips on a lilypad (0.25 px) -> +0.416

You can chain 4 blip-ups on a carpet if you start from the lower part of the blip, but at the cost of some initial height (+0.353 total).

The player will eventually reach a height lower than the top surface, thereby losing all their progress. In that sense, chained blip-ups are cyclic.

pa_O1dmuLe8

連続Wall Blip
Wall Blips can be chained in the same way as Blip-ups.

Unlike chained blip-ups, wall blips can be chained indefinitely, and it's possible to create artificially difficult jumps.

1.8より前:

 * Up until version 1.7.10, a bug prevented entities from walking onto a step under a ceiling.  Blips worked before 1.8, but could behave a bit differently in some setups due to this bug.


 * 1.8.0 is slightly different from 1.8.1+ (always lowers the bounding box by 0.6b, even when a ceiling was encountered) This difference generally has no effect on blips, but it does affect Jump-Cancelling (makes grinding impossible in 1.8.0)

1.9以降:
Because you jump higher in 1.9+ (1.252 compared to 1.249), blips are slightly affected but the mechanic still behaves the same.

For chained blips in 1.9+, each consecutive blip adds 0.121 to your initial Y position (instead of 0.104)


 * You can only blip once on 3 snow layers -> +0.121
 * You can chain up to 2 blips on a repeater -> +0.242
 * You can chain up to 3 blips on a carpet -> +0.363
 * You can no longer chain 4 blips on a lilypad or carpet.

1.14以降:
Blip-ups and Wall blips are patched. "Normal" blips still works, suggesting it's an intended mechanic.


 * Instead of lowering the bounding box by a maximum of 0.6m, the game now lowers it until it reaches the player's height minus their vertical speed.


 * This introduces a new glitch called Blip-Down, where the player can land below ground level under the right conditions. To perform a blip-down, the player must land on the edge of a block, collide with a steppable wall, while moving outwards to ensure the stepping region doesn't encounter any ground.

1.15以降:
Blipping now cancels fall damage in some cases. (patched in 1.16)