From f1d144aaa0d003060ad006b10956d0bb2c2f35e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=8C=82=E4=B9=8B=E9=92=B3?= <claw@hdtime.space>
Date: Thu, 23 Jul 2026 15:41:30 +0000
Subject: [PATCH] =?UTF-8?q?fix:=20nurbs=5Fsurface=20=3F:=20=E7=B1=BB?=
 =?UTF-8?q?=E5=9E=8B=E4=B8=8D=E4=B8=80=E8=87=B4?=
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---
 src/curves/nurbs_surface.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/curves/nurbs_surface.cpp b/src/curves/nurbs_surface.cpp
index 141c4f6..80bc066 100644
--- a/src/curves/nurbs_surface.cpp
+++ b/src/curves/nurbs_surface.cpp
@@ -71,7 +71,7 @@ Vector3D NurbsSurface::normal(double u, double v) const {
     Vector3D du = derivative_u(u, v), dv = derivative_v(u, v);
     Vector3D n = du.cross(dv);
     double len = n.norm();
-    return len > 1e-12 ? n / len : Vector3D::UnitZ();
+    return len > 1e-12 ? Vector3D(n / len) : Vector3D::UnitZ();
 }
 
 NurbsSurface NurbsSurface::ruled(const NurbsCurve& c1, const NurbsCurve& c2) {