feat: complete mobile UI implementation

project/ui/mobile/virtual_joystick.gd

@@ -0,0 +1,86 @@
+# VirtualJoystick —— continuous left-thumb movement input.
+extends Control
+
+signal axis_changed(axis: Vector2)
+
+const DEAD_ZONE := 0.12
+const KNOB_RADIUS := 29.0
+
+var _touch_index := -1
+var _axis := Vector2.ZERO
+var _knob := Vector2.ZERO
+
+func setup(diameter := 164.0) -> void:
+	custom_minimum_size = Vector2(diameter, diameter)
+	size = Vector2(diameter, diameter)
+	mouse_filter = Control.MOUSE_FILTER_STOP
+	queue_redraw()
+
+func axis() -> Vector2:
+	return _axis
+
+func _gui_input(event: InputEvent) -> void:
+	if event is InputEventScreenTouch:
+		if event.pressed and _touch_index < 0:
+			_touch_index = event.index
+			_update_from_position(event.position)
+		elif not event.pressed and event.index == _touch_index:
+			_touch_index = -1
+			_set_axis(Vector2.ZERO)
+		accept_event()
+		return
+	if event is InputEventScreenDrag and event.index == _touch_index:
+		_update_from_position(event.position)
+		accept_event()
+		return
+	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT:
+		if event.pressed:
+			_touch_index = -2
+			_update_from_position(event.position)
+		else:
+			_touch_index = -1
+			_set_axis(Vector2.ZERO)
+		accept_event()
+		return
+	if event is InputEventMouseMotion and _touch_index == -2:
+		_update_from_position(event.position)
+		accept_event()
+
+func _update_from_position(pos: Vector2) -> void:
+	var center := size * 0.5
+	var radius := maxf(1.0, minf(size.x, size.y) * 0.5 - KNOB_RADIUS - 8.0)
+	var delta := pos - center
+	var raw := delta / radius
+	var magnitude := minf(raw.length(), 1.0)
+	var direction := raw.normalized() if magnitude > 0.001 else Vector2.ZERO
+	var output := direction * magnitude
+	if output.length() < DEAD_ZONE:
+		output = Vector2.ZERO
+	else:
+		output = output.normalized() * ((output.length() - DEAD_ZONE) / (1.0 - DEAD_ZONE))
+	_knob = direction * radius * magnitude
+	_set_axis(output)
+	queue_redraw()
+
+func _set_axis(value: Vector2) -> void:
+	var next := value.limit_length(1.0)
+	if next.is_equal_approx(_axis):
+		return
+	_axis = next
+	axis_changed.emit(_axis)
+	queue_redraw()
+
+func cancel_press() -> void:
+	_touch_index = -1
+	_knob = Vector2.ZERO
+	_set_axis(Vector2.ZERO)
+
+func _draw() -> void:
+	var center := size * 0.5
+	var outer := minf(size.x, size.y) * 0.5 - 5.0
+	if outer <= 0.0:
+		return
+	draw_circle(center, outer, Color(0.025, 0.04, 0.07, 0.38))
+	draw_arc(center, outer, 0.0, TAU, 48, Color(0.72, 0.83, 0.96, 0.42), 2.0)
+	draw_circle(center + _knob, KNOB_RADIUS, Color(0.18, 0.3, 0.48, 0.78))
+	draw_arc(center + _knob, KNOB_RADIUS, 0.0, TAU, 32, Color(0.7, 0.85, 1.0, 0.8), 2.0)