From 5930b5c09d1a4a86773ba2cdfbf9c7138ba5afe4 Mon Sep 17 00:00:00 2001
From: Emmett Lalish <elalish@gmail.com>
Date: Thu, 2 Nov 2023 12:35:44 -0700
Subject: [PATCH] Fix NaN halfedgeTangents (#588)

fixed CreateTangents
---
 src/manifold/src/smoothing.cpp |  9 ++++++---
 test/sdf_test.cpp              | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/src/manifold/src/smoothing.cpp b/src/manifold/src/smoothing.cpp
index 8272eb0d3..77924baac 100644
--- a/src/manifold/src/smoothing.cpp
+++ b/src/manifold/src/smoothing.cpp
@@ -196,10 +196,13 @@ struct SmoothBezier {
     const glm::vec3 edgeNormal =
         (triNormal[edge.face] + triNormal[halfedge[edge.pairedHalfedge].face]) /
         2.0f;
-    glm::vec3 dir = glm::normalize(glm::cross(glm::cross(edgeNormal, edgeVec),
-                                              vertNormal[edge.startVert]));
+    glm::vec3 dir = SafeNormalize(glm::cross(glm::cross(edgeNormal, edgeVec),
+                                             vertNormal[edge.startVert]));
 
-    const float weight = glm::abs(glm::dot(dir, glm::normalize(edgeVec)));
+    float weight = glm::abs(glm::dot(dir, SafeNormalize(edgeVec)));
+    if (weight == 0) {
+      weight = 1;
+    }
     // Quadratic weighted bezier for circular interpolation
     const glm::vec4 bz2 =
         weight *
diff --git a/test/sdf_test.cpp b/test/sdf_test.cpp
index 00f486250..23257ec3c 100644
--- a/test/sdf_test.cpp
+++ b/test/sdf_test.cpp
@@ -115,3 +115,21 @@ TEST(SDF, Resize) {
   EXPECT_EQ(layers.Status(), Manifold::Error::NoError);
   EXPECT_EQ(layers.Genus(), -8);
 }
+
+TEST(SDF, SineSurface) {
+  Mesh surface(LevelSet(
+      [](glm::vec3 p) {
+        float mid = glm::sin(p.x) + glm::sin(p.y);
+        return (p.z > mid - 0.5 && p.z < mid + 0.5) ? 1 : 0;
+      },
+      {glm::vec3(-4 * glm::pi<float>()), glm::vec3(4 * glm::pi<float>())}, 1));
+  Manifold smoothed = Manifold::Smooth(surface).Refine(2);
+
+  EXPECT_EQ(smoothed.Status(), Manifold::Error::NoError);
+  EXPECT_EQ(smoothed.Genus(), -2);
+
+#ifdef MANIFOLD_EXPORT
+  if (options.exportModels)
+    ExportMesh("sinesurface.glb", smoothed.GetMeshGL(), {});
+#endif
+}
\ No newline at end of file