class_name Block
extends AnimatableBody2D
## One arc-shaped segment of a ring around the core.

var indestructible := false
var color := Params.COLOR_BLUE
var _polygon := PackedVector2Array()


func _init(inner: float, outer: float, begin: float, end: float, is_indestructible: bool) -> void:
	sync_to_physics = false
	collision_layer = Params.LAYER_BLOCKS
	collision_mask = 0
	indestructible = is_indestructible

	# Leave a ~1px gap between neighbouring segments.
	begin += 1.0 / outer
	end -= 1.0 / outer
	var steps := maxi(2, int((end - begin) * sqrt(outer) / 1.5))
	var outer_arc := _arc(outer, begin, end, steps)
	# The drawn shape stops 2px short of the inner radius to leave a gap between rings.
	_polygon = outer_arc + _arc(inner + 2.0, end, begin, steps)

	var collision := CollisionPolygon2D.new()
	collision.polygon = outer_arc + _arc(inner, end, begin, steps)
	add_child(collision)

	if indestructible:
		color = Params.COLOR_ORANGE
	else:
		color = Color8(
			int(102 * (randf() / 5.0 + 0.5)),
			int(217 * (randf() / 5.0 + 0.5)),
			int(239 * (randf() / 5.0 + 0.5)))


func destroy() -> void:
	collision_layer = 0
	queue_free()


func _draw() -> void:
	draw_colored_polygon(_polygon, color)
	# Polygons have no antialiasing of their own; a smooth outline softens the edge.
	var outline := _polygon.duplicate()
	outline.append(_polygon[0])
	draw_polyline(outline, color, 1.0, true)


static func _arc(radius: float, from: float, to: float, steps: int) -> PackedVector2Array:
	var points := PackedVector2Array()
	for i in steps + 1:
		var angle := lerpf(from, to, float(i) / steps)
		points.append(Vector2(sin(angle), cos(angle)) * radius)
	return points