Polish world, shop, and artwork presentation

tests/shoreline_ribbon_validation.gd

@@ -0,0 +1,97 @@
+extends SceneTree
+
+const ShorelineMesh: ArrayMesh = preload(
+	"res://world/generated/shorelines/starter_ocean_shoreline.tres"
+)
+const GEOMETRY_EPSILON := 0.0001
+const CROSSING_NEIGHBORHOOD := 32
+
+
+func _initialize() -> void:
+	call_deferred("_run")
+
+
+func _run() -> void:
+	assert(ShorelineMesh.get_surface_count() == 1)
+	var arrays := ShorelineMesh.surface_get_arrays(0)
+	var vertices := arrays[Mesh.ARRAY_VERTEX] as PackedVector3Array
+	var indices := arrays[Mesh.ARRAY_INDEX] as PackedInt32Array
+	assert(not vertices.is_empty())
+	assert(vertices.size() % 2 == 0)
+	assert(indices.size() == vertices.size() * 3)
+	var point_count := vertices.size() / 2
+	var land_edge := PackedVector2Array()
+	var water_edge := PackedVector2Array()
+	for index: int in point_count:
+		var land := vertices[index * 2]
+		var water := vertices[index * 2 + 1]
+		land_edge.append(Vector2(land.x, land.z))
+		water_edge.append(Vector2(water.x, water.z))
+		var ribbon_width := land.distance_to(water)
+		assert(ribbon_width >= 0.34)
+		assert(ribbon_width <= 1.5)
+	var crossing_count := (
+		_count_local_crossings(water_edge)
+		+ _count_local_crossings(land_edge)
+	)
+	if crossing_count > 0:
+		push_error(
+			"Shoreline ribbon contains %d local edge crossings."
+			% crossing_count
+		)
+		quit(1)
+		return
+	print("Shoreline ribbon validation: PASS")
+	quit()
+
+
+func _count_local_crossings(points: PackedVector2Array) -> int:
+	var crossing_count := 0
+	for first: int in points.size():
+		var first_next := (first + 1) % points.size()
+		var checked_neighbors := mini(
+			CROSSING_NEIGHBORHOOD,
+			points.size() - 2,
+		)
+		for offset: int in range(2, checked_neighbors + 1):
+			var second := (first + offset) % points.size()
+			var second_next := (second + 1) % points.size()
+			if second_next == first:
+				continue
+			if _segments_cross(
+				points[first],
+				points[first_next],
+				points[second],
+				points[second_next],
+			):
+				crossing_count += 1
+	return crossing_count
+
+
+func _segments_cross(
+	a: Vector2,
+	b: Vector2,
+	c: Vector2,
+	d: Vector2,
+) -> bool:
+	if (
+		maxf(a.x, b.x) < minf(c.x, d.x) - GEOMETRY_EPSILON
+		or maxf(c.x, d.x) < minf(a.x, b.x) - GEOMETRY_EPSILON
+		or maxf(a.y, b.y) < minf(c.y, d.y) - GEOMETRY_EPSILON
+		or maxf(c.y, d.y) < minf(a.y, b.y) - GEOMETRY_EPSILON
+	):
+		return false
+	var first_direction := b - a
+	var second_direction := d - c
+	var denominator := first_direction.cross(second_direction)
+	if absf(denominator) <= GEOMETRY_EPSILON:
+		return false
+	var offset := c - a
+	var first_amount := offset.cross(second_direction) / denominator
+	var second_amount := offset.cross(first_direction) / denominator
+	return (
+		first_amount > GEOMETRY_EPSILON
+		and first_amount < 1.0 - GEOMETRY_EPSILON
+		and second_amount > GEOMETRY_EPSILON
+		and second_amount < 1.0 - GEOMETRY_EPSILON
+	)