class_name HudInstrument
extends Control

# Shared base for the HUD's procedural instruments (heading tape, attitude
# indicator, gauges): the exponential-smoothing weight calc and the
# angle-aware lerp helper they all use. Each instrument still owns its own
# _process (smoothing 1-2 distinct fields) and _draw (entirely bespoke).

const SMOOTHING := 12.0


static func lerp_angle_deg(from: float, to: float, weight: float) -> float:
	return rad_to_deg(lerp_angle(deg_to_rad(from), deg_to_rad(to), weight))


# Shortest signed distance from `from` to `to` in degrees, wrapped to
# [-180, 180]. Use this (never a plain subtraction) to decide whether an
# angle that wraps around (heading, roll) has moved enough to redraw —
# a naive delta gives a false-large jump at the 0/360 boundary.
static func angle_delta_deg(from: float, to: float) -> float:
	return wrapf(to - from, -180.0, 180.0)


func _smoothing_weight(delta: float) -> float:
	return 1.0 - exp(-SMOOTHING * delta)  # frame-rate independent


# Procedural draw calls do not automatically consume a Control's theme font;
# resolve it explicitly so every instrument uses the same packaged typeface
# as ordinary Labels instead of ThemeDB's debug-looking fallback.
func hud_font() -> Font:
	var font := get_theme_default_font()
	return font if font else ThemeDB.fallback_font