first commit

scripts/track.gd

@@ -0,0 +1,61 @@
+extends Node3D
+## Baut aus 2D-Stuetzpunkten eine geschlossene Gleisschleife inkl. Optik.
+
+const Mat = preload("res://scripts/mat.gd")
+const Deco = preload("res://scripts/deco.gd")
+
+const BALLAST := Color("d98d4a")
+const SLEEPER := Color("5e4130")
+const RAIL := Color("9a9da2")
+const STEP := 1.2
+
+var path: Path3D
+
+func build(points: PackedVector2Array) -> void:
+	path = Path3D.new()
+	path.name = "TrackPath"
+	var c := Curve3D.new()
+	var n := points.size()
+	# Catmull-Rom Tangenten -> weiche, geschlossene Schleife.
+	for i in n + 1:
+		var idx := i % n
+		var prev := points[(idx - 1 + n) % n]
+		var nxt := points[(idx + 1) % n]
+		var t := (nxt - prev) / 6.0
+		var p := points[idx]
+		c.add_point(Vector3(p.x, 0, p.y), Vector3(-t.x, 0, -t.y), Vector3(t.x, 0, t.y))
+	path.curve = c
+	add_child(path)
+	_build_visuals()
+
+func length() -> float:
+	return path.curve.get_baked_length()
+
+func sample(offset: float) -> Transform3D:
+	return path.curve.sample_baked_with_rotation(fposmod(offset, length()), true, true)
+
+func _build_visuals() -> void:
+	var count := int(length() / STEP)
+	var xf: Array[Transform3D] = []
+	for i in count:
+		xf.append(sample(i * STEP))
+
+	_multi(Deco.box(Vector3(2.7, 0.16, STEP * 1.12)), BALLAST, xf, [Vector3(0, 0.08, 0)])
+	_multi(Deco.box(Vector3(2.1, 0.09, 0.34)), SLEEPER, xf, [Vector3(0, 0.20, 0)])
+	_multi(Deco.box(Vector3(0.09, 0.11, STEP * 1.08)), RAIL, xf,
+		[Vector3(-0.62, 0.29, 0), Vector3(0.62, 0.29, 0)])
+
+func _multi(mesh: Mesh, color: Color, xf: Array[Transform3D], offsets: Array) -> void:
+	var mm := MultiMesh.new()
+	mm.transform_format = MultiMesh.TRANSFORM_3D
+	mm.mesh = mesh
+	mm.instance_count = xf.size() * offsets.size()
+	var i := 0
+	for t in xf:
+		for o in offsets:
+			mm.set_instance_transform(i, t.translated_local(o))
+			i += 1
+	var mmi := MultiMeshInstance3D.new()
+	mmi.multimesh = mm
+	mmi.material_override = Mat.flat(color)
+	add_child(mmi)