Movement Formulas

The Player's movement can be accurately calculated with sequences.

The following formulas come from analyzing the game's source code.

Because this field is so extensive, we're only considering standard movement, and ignoring mechanics specific to certain blocks.

You will find further documentation of movement physics in these articles:


 * Soulsand
 * Ladders and Vines
 * Slime Blocks
 * Cobwebs

Jump Formula:

 * $$V\displaystyle _{Y}(0) = 0.42$$
 * $$V\displaystyle _{Y}(t) = \left (V_{Y}(t-1) - \underset{gravity}{0.08} \right ) \times \underset{drag}{0.98}$$


 * If $ \left | V\displaystyle _{Y}(t) \right | < 0.005 $,  $V\displaystyle _{Y}(t)$  is set to 0 instead.


 * In 1.9+, it's compared to 0.003 instead.

Notes:

 * $ V\displaystyle _{Y}(0)$ corresponds to the initial jump motion.
 * $ V\displaystyle _{Y}(0)$ is increased by 0.1 per level of Jump Boost
 * Terminal velocity is -3.92 b/t
 * When the Player collides vertically with a block, $V\displaystyle _{Y}(t)$ is set to 0.

Vertical Position:

 * To get the position on a given tick, you simply need to sum $V\displaystyle _{Y}$


 * $Y(n) = \sum_{t=0}^{n} V_{Y}(t)$

Airtime:

 * The airtime of a jump is the number of ticks between jumping and landing.


 * It also corresponds to the period (in ticks) of that jump's cycle when performed repeatedly.


 * Airtime is linked to the notion of Tiers.


 * {| class="wikitable"

!Description !Airtime
 * Flat Jump
 * 12 t
 * 3bc Jump
 * 11 t
 * +0.5 Jump
 * 10 t
 * +1 Jump
 * 9 t
 * 2.5bc Jump
 * 6 t
 * 2bc Jump
 * 3 t
 * 1.8125bc Jump
 * 2 t
 * }
 * 2bc Jump
 * 3 t
 * 1.8125bc Jump
 * 2 t
 * }
 * 2 t
 * }

Horizontal Movement
Horizontal Movement is a bit more complex than Vertical Movement, as it relies on many more factors: Player Actions, Direction, and Ground Slipperiness.

On every tick, the game does these steps:
 * 1) Acceleration is added to the Player's speed.
 * 2) The Player is moved (new position = position + velocity).
 * 3) The Player's velocity is reduced to simulate air resistance.

We'll start by introducing Multipliers in an effort to make formulas more readable.

Multipliers

 * Movement Multiplier (See 45° Strafe)


 * $$M(t) = \begin{Bmatrix}1.3 & \textrm{Sprinting} \\ 1.0 & \textrm{Walking}\\ 0.3 & \textrm{Sneaking}\\ 0.0 & \textrm{Stopping} \end{Bmatrix} \times \begin{Bmatrix}0.98 & \textrm{Default}\\ 1.0 & \textrm{45° Strafe} \\ 0.98 \sqrt{2} & \textrm{45° Sneak} \end{Bmatrix}$$


 * Effects Multiplier (See Status Effects)


 * $$E(t) = (\underset{Decreases \; by \; 15\% \; per \; level \; of \; Slowness}{\underset{Increases \; by \; 20\% \; per \; level \; of \; Speed}{\underbrace{\left ( 1 + 0.2\times Speed \right ) \: \times\: \left ( 1 - 0.15\times Slowness \right )}}} \geq 0$$


 * Slipperiness Multiplier (See Slipperiness)


 * $$S(t) = \begin{Bmatrix}0.6 & \textrm{Default}\\ 0.8 & \textrm{Slime}\\ 0.98& \textrm{Ice} \\ 1.0 & \textrm{Airborne} \end{Bmatrix}$$

Linear Formulas

 * These simplified formulas only apply to linear movement (no change in direction).


 * While this condition might seem very restrictive, these formulas are very useful to analyze conventional jumps and momentum.


 * We'll later expand on these formulas by including angles.


 * Ground Speed:


 * $$V(t) = \underset{Inertia}{\underbrace{\underset{ }{V(t-1) \times S(t-1) \times 0.91 }}} \: + \: \underset{Acceleration}{\underbrace{0.1 \times M(t) \times E(t) \times \left (\frac{0.6}{S(t)}  \right )^{3}}} $$


 * Jump Speed:


 * $$V(t) = \underset{Inertia}{\underbrace{\underset{ }{V(t-1) \times S(t-1) \times 0.91 }}} \: + \: \underset{Acceleration}{\underbrace{0.1 \times M(t) \times E(t) \times \left (\frac{0.6}{S(t)}  \right )^{3}}} + \underset{Sprintjump \; Boost}{\underbrace{\begin{Bmatrix}0.2 & \textrm{Sprinting}\\ 0.0   & \textrm{Else}\end{Bmatrix} }}$$


 * Air Speed:


 * $$V(t) = \underset{Inertia}{\underbrace{\underset{ }{V(t-1) \times S(t-1) \times 0.91 }}} \: + \: \underset{Acceleration}{\underbrace{\underset{ }{0.02 \times M(t)}}} $$

Complete Formulas

 * Let's introduce two more variables:
 * $ D(t) $, The player's Direction in degrees (defined by their inputs and rotation)
 * $ F(t) $, The player's Facing in degrees (defined by their rotation)

In reality, angles aren't as simple as that, as there are a limited number of significant angles (see Facing and Angles).

For the purpose of simplicity, we'll assume $ D(t) $ and $ F(t) $  are not affected by yaw-to-angle conversion.


 * Ground Speed:


 * $$V\displaystyle _{X}(t) = \underset{ }{V\displaystyle _{X}(t-1) \times S(t-1) \times 0.91 } \: + \: 0.1 \times M(t) \times E(t) \times \left (\frac{0.6}{S(t)}  \right )^{3} \times \sin (D(t)) $$
 * $$V\displaystyle _{Z}(t) = \underset{Inertia}{\underbrace{\underset{ }{V\displaystyle _{Z}(t-1) \times S(t-1) \times 0.91 }}} \: + \: \underset{Acceleration}{\underbrace{0.1 \times M(t) \times E(t) \times \left (\frac{0.6}{S(t)}  \right )^{3}}} \times \cos (D(t)) $$


 * Jump Speed:


 * $$V\displaystyle _{X}(t) = \underset{ }{V\displaystyle _{X}(t-1) \times S(t-1) \times 0.91 } \: + \: 0.1 \times M(t) \times E(t) \times \left (\frac{0.6}{S(t)}  \right )^{3} \times \sin (D(t)) + \begin{Bmatrix} 0.2 & \textrm{Sprinting}\\ 0.0 & \textrm{Else}\end{Bmatrix} \times \sin (F(t)) $$
 * $$V\displaystyle _{Z}(t) = \underset{Inertia}{\underbrace{\underset{ }{V\displaystyle _{Z}(t-1) \times S(t-1) \times 0.91 }}} \: + \: \underset{Acceleration}{\underbrace{0.1 \times M(t) \times E(t) \times \left (\frac{0.6}{S(t)}  \right )^{3}}} \times \cos (D(t)) + \underset{Sprintjump \; Boost }{\underbrace{\begin{Bmatrix} 0.2 & \textrm{Sprinting}\\ 0.0 & \textrm{Else}\end{Bmatrix} \times \cos (F(t))}} $$


 * Air Speed:


 * $$V\displaystyle _{X}(t) = \underset{ }{V\displaystyle _{X}(t-1) \times S(t-1) \times 0.91 } \: + \: 0.02 \times M(t) \times \sin (D(t)) $$
 * $$V\displaystyle _{Z}(t) = \underset{Inertia}{\underbrace{\underset{ }{V\displaystyle _{Z}(t-1) \times S(t-1) \times 0.91 }}} \: + \: \underset{Acceleration}{\underbrace{\underset{}{0.02 \times M(t)}}} \times \cos (D(t)) $$

Stopping Conditions

 * Horizontal speed is set to 0 if the Player hits a wall, or if the speed is considered to be negligible.


 * Wall Collision:


 * If the player hits a X-facing wall, then $V\displaystyle _{X}(t)$ is set to 0 and the Player is placed against the wall.
 * If the player hits a Z-facing wall, then $V\displaystyle _{Z}(t)$ is set to 0 and the Player is placed against the wall.


 * Negligible Speed:


 * If $ \left | V\displaystyle _{X}(t) \right | < 0.005 $ after applying inertia,   $ V\displaystyle_{X}(t)$  is set to 0.
 * If $ \left | V\displaystyle _{Z}(t) \right | < 0.005 $ after applying inertia,   $ V\displaystyle_{Z}(t)$  is set to 0.


 * In 1.9+, they are compared to 0.003 instead.