Struct Deadzone

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pub struct Deadzone { /* private fields */ }

Expand description

A radial dead region around stick centre, with the scaled response the literature settles on.

Three games on the PSoXide demo disc had grown one of these and they did not agree. hl-psx tests x*x + y*y against a squared radius. VoXide gates each axis separately, which makes its dead region a square: a stick pushed gently along a diagonal clears the threshold on one axis and not the other, so the input snaps to a cardinal instead of going where it was pushed. Sutphin’s write-up calls that the axial dead zone and its snapping is the classic complaint about it.

A stick’s centre drift is radial, so the region that ignores it is a circle, and Deadzone::scaled is the scaled-radial form: remapped so the first real reading starts from zero rather than jumping to the boundary magnitude. That is the recommended default. Deadzone::gate is the plain radial one, kept because the games being replaced were tuned against it.

This is for two-axis input. A single-axis control is a different question and a scalar threshold is right for it: NitroXide steers on the left stick’s X alone, and folding Y into the test there would let noise on an axis it does not read enable steering. See Deadzone::is_outside_axis.

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impl Deadzone

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pub const fn new(radius: i16) -> Self

A dead region of radius counts around centre. Typical radii are 12 to 30 of the 127 counts a healthy stick reaches. A negative radius is no dead region (zero): the squared test would otherwise treat it as its absolute value while scaled divided by a zero length.

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pub const fn with_outer(self, outer: i16) -> Self

Treat any deflection at or beyond outer as full scale.

A worn stick often cannot reach its corners, so without this the player simply never gets full input. Sutphin recommends exposing it as a setting for anything where magnitude matters.

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pub const fn radius(self) -> i16

The inner radius this was built with.

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pub const fn is_outside(self, x: i16, y: i16) -> bool

Is this reading real input rather than centre drift?

Strictly outside, matching the boundary behaviour of the games this replaces.

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pub const fn gate(self, x: i16, y: i16) -> Option<(i16, i16)>

The reading unchanged if it is real input, or None inside the dead region. The plain radial form: direction is preserved, but magnitude jumps from zero to the boundary the moment it is crossed.

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pub fn scaled(self, x: i16, y: i16) -> Option<(i16, i16)>

Scaled radial: None inside the dead region, otherwise the reading with its magnitude remapped from the dead edge onto full scale, keeping direction.

The result is clamped to STICK_FULL per axis. Without that a full diagonal, which is 179 counts long rather than 127, remaps to 138 on each axis and hands the game 9% more than it believes the stick can produce.

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