Mouse Movement/zh

鼠标移动表示光标在屏幕上的瞬时位移（以像素为单位）： (${\textstyle dx,dy}$)。

在《我的世界》中，鼠标移动代表视角的即时旋转(以角度表示)： (${\textstyle \Delta x,\Delta y}$)。

灵敏度

灵敏度(s)是一个参数，用于改变视角的旋转速度。

可以在“控制”菜单中更改此设置。

• 默认灵敏度为"100%" (${\textstyle s=0.5}$)

• 原版中最低的灵敏度是"0%" (${\textstyle s=0.0}$)
• 原版中最高的灵敏度是"200%" (${\textstyle s=1.0}$)

在1.8中， ${\textstyle \Delta x}$ 计算如下:

$\Delta x=1.2dx\times (0.6s+0.2)^{3}$

${\textstyle \Delta y}$ is obtained in the same way, and is multiplied by -1 if "Invert Mouse" is ON.

With default sensitivity (${\textstyle s=0.5}$), one pixel of mouse movement translates into 0.15° of rotation.

This means that the camera moves in increments of 0.15°: to turn 45°, you would need to move your mouse by 300px.

Furthermore, s isn't technically bounded by [0,1], and can take any value (even negative).

You can manually edit the value of mouseSensitivity in the options.txt file (found in the .minecraft folder)

Be warned that modifying the options.txt file may or may not be allowed on servers.

Remarkable values

Since it's possible to set the sensitivity to any value we want, it might be interesting to adjust the sensitivity to match specific rotation increments.

To get the required sensitivity for the desired increment ${\textstyle \delta }$, we can use the inverse formula:

$s={\frac {{\sqrt[{3}]{\frac {\delta }{1.2}}}-0.2}{0.6}}$

This table lists remarkable increments of rotation, and the corresponding values of s.

${\textstyle \delta }$	s
0°	-0.3333333
0.1°	0.3946504
0.15°	0.5
0.25°	0.6546926
0.5°	0.9115013
1°	1.2350600
45°	5.2452746
180°	8.5221547

Yaw and Pitch

Yaw (horizontal rotation) and pitch (vertical rotation) are floats that keep track of an entity's head rotation.

Facing is the restriction of the yaw to [-180, 180], as it is represented in F3. Pitch is naturally clamped between [-90, 90].

Mouse movement directly modifies the player's yaw and pitch:

/* In EntityRenderer.java */
public void updateMouseMovement(...)
{
    ... //previous code ignored
</div>

    <div lang="en" dir="ltr" class="mw-content-ltr">
float f = this.mc.gameSettings.mouseSensitivity * 0.6F + 0.2F;
    float mult = f * f * f * 8.0F;
    float dX = (float)this.mc.mouseHelper.deltaX * mult;
    float dY = (float)this.mc.mouseHelper.deltaY * mult;
</div>

    <div lang="en" dir="ltr" class="mw-content-ltr">
int i = 1;
    if (this.mc.gameSettings.invertMouse)
        i = -1;
</div>

    <div lang="en" dir="ltr" class="mw-content-ltr">
... //Applies filters if smooth camera
</div>

    <div lang="en" dir="ltr" class="mw-content-ltr">
this.mc.thePlayer.rotateEntity(dX, dY*i);
}
</div>


<div lang="en" dir="ltr" class="mw-content-ltr">
/* In Entity.java */
public void rotateEntity(float dX, float dY)
{
    this.rotationYaw = this.rotationYaw + dX*0.15);
    this.rotationPitch = this.rotationPitch - dY*0.15;
    this.rotationPitch = MathHelper.clamp(this.rotationPitch, -90.0, 90.0);
}

While the pitch is clamped between -90° and 90°, yaw is not restricted between -180° and 180° as would be expected.

This means that yaw is unbounded, which has some unintended consequences if you deliberately turn in one direction for long enough.

By nature of being a float, its precision becomes worse the bigger it gets, to the point where it becomes noticeably jittery at large values.

• When $|yaw|>4194304$ (${\textstyle 2^{22}}$) it can only increase in increments of 0.5°.
• When $|yaw|>8388608$ (${\textstyle 2^{23}}$) it can only increase in increments of 1°.

At some point, yaw can even mess with movement and stop the player in place.

This is because the yaw gets too large to be converted to a proper angle (see Angles).

This phenomenon happens when $|yaw|\geq 11796480=360\times 2^{15}$.

Turning even further can crash the game, when ${\textstyle |yaw|>8.59\times 10^{9}}$