ジャンプ

Jumping is an essential mechanic that is quite self-explanatory.

発動

ジャンプするには、その前のtickで地面に立っている必要がある。ブロック縁からでも1tick走って（例:ずらし）ジャンプできるのはこのためである。

ジャンプキーを押し続けていると、10tick（0.5秒）ごとに1回ジャンプできる。

• 各ジャンプの高さが0.75b以上の場合、ジャンプキーを押し続けるのは最適ではない（結果: ブロックを積み上げる時は押し直しの方が速い）。
• Releasing jump resets the cooldown, making the player able to jump again on the next tick.

When a jump is initiated, the player's vertical speed is set to 0.42. On every following tick, it is decreased by 0.08 (gravity), then multiplied by 0.98 (drag).

• When the player hits a ceiling, their vertical speed is set to 0 and they immediately start falling.
• When the player hits the ground, their vertical speed is set to 0 and the onGround flag is set as true.

Jumping in water or lava makes the player move upward.

ジャンプの高さ

1.8以前はジャンプの最高点は1.249b。1.9で約0.003b上昇し、1.252bの高さまでジャンプできるようになった。

平らな地面では、1ジャンプの長さは12tick（0.6秒）。

速度

When combined with Sprinting, jumping adds 0.2 units of acceleration towards the player's facing.

In air, the player accelerates less quickly (only 20% of the base acceleration value), but conserves more speed (91% every tick, instead of 54.6%).

Therefore, sprint-jumping is a very efficient way to build and conserve speed.

ソースコード

The following snippets of code deal with how jump is activated.

/* From EntityLivingBase.java, stripped of irrelevant code */
public void onLivingUpdate()
{
    if (this.jumpTicks > 0)
        --this.jumpTicks;
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    <div lang="en" dir="ltr" class="mw-content-ltr">
if (this.isJumping)
    {
        if (this.isInWater())
            this.handleJumpWater(); //motionY += 0.04
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        <div lang="en" dir="ltr" class="mw-content-ltr">
else if (this.isInLava())
            this.handleJumpLava();  //motionY += 0.04
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        else if (this.onGround && this.jumpTicks == 0)
        {
                this.jump();
                this.jumpTicks = 10;
        }
    }

    <div lang="en" dir="ltr" class="mw-content-ltr">
//releasing the jump key resets the 10 tick cooldown.
    else
        this.jumpTicks = 0;
}
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<div lang="en" dir="ltr" class="mw-content-ltr">
/* From EntityLivingBase.java */
protected void jump()
{
    this.motionY = 0.42; //Initial speed
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//apply jump boost
    if (this.isPotionActive(Potion.jump))
        this.motionY += (this.getActivePotionEffect(Potion.jump).getAmplifier() + 1) * 0.1F;
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    <div lang="en" dir="ltr" class="mw-content-ltr">
//apply sprintjump boost
    if (this.isSprinting())
    {
        float f = this.rotationYaw * 0.017453292F; //multiply by pi/180 to convert to radians
        this.motionX -= MathHelper.sin(f) * 0.2F;
        this.motionZ += MathHelper.cos(f) * 0.2F;
    }
}