Fix ball rolling animation (queue_redraw on roll_angle) and realistic marble design (codex)

scripts/ball.gd

@@ -14,7 +14,10 @@ var radius := 40.0
 var home_pos := Vector2.ZERO
 var left_pos := Vector2.ZERO
 var in_motion := false
-var roll_angle := 0.0   # rotazione della biglia durante il rotolamento
+var roll_angle := 0.0:
+	set(v):
+		roll_angle = v
+		queue_redraw()  # aggiorna il disegno a ogni step di rotazione
 var _tween: Tween
 
 
@@ -27,13 +30,47 @@ func _draw() -> void:
 	draw_circle(Vector2(radius * 0.18, radius * 0.22), radius * 0.92, Color(0, 0, 0, 0.16))
 	# luce superiore-sinistra
 	draw_circle(Vector2(-radius * 0.18, -radius * 0.22), radius * 0.92, Color(1, 1, 1, 0.2))
+	# marmorizzazione a vortici che ruota col rotolamento (design realistico)
+	_draw_marbling()
 	# bordo nero spesso (stile china)
 	draw_arc(Vector2.ZERO, radius, 0.0, TAU, 48, Color(0.1, 0.1, 0.1, 0.9), 4.0)
-	# riflesso speculare
+	# riflesso speculare (fisso: la luce non ruota con la superficie)
 	draw_circle(Vector2(-radius * 0.3, -radius * 0.34), radius * 0.16, Color(1, 1, 1, 0.85))
-	# segno che ruota mentre la biglia rotola
-	var spot := Vector2(cos(roll_angle), sin(roll_angle)) * radius * 0.55
-	draw_circle(spot, radius * 0.12, Color(0, 0, 0, 0.28))
+
+
+func _draw_marbling() -> void:
+	# Tre venature curve, irregolari e non simmetriche. Tutta la geometria
+	# superficiale ruota; illuminazione e riflesso vengono invece disegnati dopo.
+	var vein_color: Color = ball_color.darkened(0.42)
+	vein_color.a = 0.20
+	var soft_color: Color = ball_color.darkened(0.28)
+	soft_color.a = 0.12
+	var veins: Array[PackedVector2Array] = [
+		_make_vein(-0.72, -0.22, 0.68, -0.06, 0.15, 0.09),
+		_make_vein(-0.55, 0.34, 0.34, 0.60, -0.13, 0.07),
+		_make_vein(-0.18, -0.64, 0.58, -0.40, -0.10, 0.06),
+	]
+	for i: int in range(veins.size()):
+		var rotated_points := PackedVector2Array()
+		for point: Vector2 in veins[i]:
+			rotated_points.append(point.rotated(roll_angle))
+		var width: float = radius * (0.075 if i == 0 else 0.045)
+		draw_polyline(rotated_points, soft_color, width * 1.9, true)
+		draw_polyline(rotated_points, vein_color, width, true)
+
+
+func _make_vein(x0: float, y0: float, x1: float, y1: float,
+		bend: float, ripple: float) -> PackedVector2Array:
+	var points := PackedVector2Array()
+	var direction := Vector2(x1 - x0, y1 - y0)
+	var normal := direction.normalized().orthogonal()
+	for step: int in range(17):
+		var t: float = float(step) / 16.0
+		var base := Vector2(lerpf(x0, x1, t), lerpf(y0, y1, t))
+		var curve: float = sin(t * PI) * bend
+		var wave: float = sin(t * TAU * 1.35 + x0 * 4.0) * ripple
+		points.append((base + normal * (curve + wave)) * radius)
+	return points
 
 
 func setup(cn: String, c: Color, home: Vector2, left: Vector2, r: float) -> void:
@@ -60,6 +97,7 @@ func reset() -> void:
 		_tween.kill()
 	in_motion = false
 	position = home_pos
+	roll_angle = 0.0
 
 
 ## Lancia la pallina verso sinistra e la fa tornare a casa. `mt` è il tempo
@@ -68,10 +106,10 @@ func launch(mt: float) -> void:
 	in_motion = true
 	if _tween and _tween.is_valid():
 		_tween.kill()
-	var half := maxf(mt * 0.5, 0.01)
+	var half: float = maxf(mt * 0.5, 0.01)
 	# rotazione proporzionale alla distanza percorsa (rotolamento)
-	var dist := home_pos.x - left_pos.x
-	var total_angle := dist / radius
+	var dist: float = home_pos.x - left_pos.x
+	var total_angle: float = dist / radius
 	_tween = create_tween()
 	_tween.tween_property(self, "position", left_pos, half) \
 		.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_IN_OUT)