From bb2734ba3359d8bc1c9750d708b5fa9b2bac1383 Mon Sep 17 00:00:00 2001
From: Jeremy HU <huxingyi@msn.com>
Date: Wed, 12 Oct 2022 23:30:07 +1100
Subject: [PATCH] Add subdivide face

---
 dust3d/mesh/base_normal.cc       |  2 +-
 dust3d/mesh/mesh_generator.cc    | 14 ++++++++++++++
 dust3d/mesh/mesh_generator.h     |  1 +
 dust3d/mesh/tube_mesh_builder.cc |  6 ++++++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/dust3d/mesh/base_normal.cc b/dust3d/mesh/base_normal.cc
index fbb478a7..cc684ae8 100644
--- a/dust3d/mesh/base_normal.cc
+++ b/dust3d/mesh/base_normal.cc
@@ -89,7 +89,7 @@ Vector3 BaseNormal::calculateTubeBaseNormal(const std::vector<Vector3> &vertices
         size_t h = i - 1;
         // >15 degrees && < 165 degrees
         if (std::abs(Vector3::dotProduct(edgeDirections[h], edgeDirections[i])) < 0.966)
-            baseNormal += Vector3::crossProduct(edgeDirections[h], edgeDirections[i]);
+            baseNormal += Vector3::crossProduct(-edgeDirections[h], edgeDirections[i]);
     }
     if (baseNormal.isZero()) {
         for (size_t h = 0; h + 1 < edgeDirections.size(); ++h) {
diff --git a/dust3d/mesh/mesh_generator.cc b/dust3d/mesh/mesh_generator.cc
index 1736b7dd..768a062b 100644
--- a/dust3d/mesh/mesh_generator.cc
+++ b/dust3d/mesh/mesh_generator.cc
@@ -93,6 +93,18 @@ void MeshGenerator::chamferFace(std::vector<Vector2> *face)
     }
 }
 
+void MeshGenerator::subdivideFace(std::vector<Vector2> *face)
+{
+    auto oldFace = *face;
+    face->resize(oldFace.size() * 2);
+    for (size_t i = 0, n = 0; i < oldFace.size(); ++i) {
+        size_t h = (i + oldFace.size() - 1) % oldFace.size();
+        size_t j = (i + 1) % oldFace.size();
+        (*face)[n++] = oldFace[h] * 0.125 + oldFace[i] * 0.75 + oldFace[j] * 0.125;
+        (*face)[n++] = (oldFace[i] + oldFace[j]) * 0.5;
+    }
+}
+
 bool MeshGenerator::isWatertight(const std::vector<std::vector<size_t>> &faces)
 {
     std::set<std::pair<size_t, size_t>> halfEdges;
@@ -596,6 +608,8 @@ std::unique_ptr<MeshCombiner::Mesh> MeshGenerator::combinePartMesh(const std::st
     cutFaceStringToCutTemplate(cutFaceString, cutTemplate);
     if (chamfered)
         chamferFace(&cutTemplate);
+    if (subdived)
+        subdivideFace(&cutTemplate);
     
     std::string cutRotationString = String::valueOrEmpty(part, "cutRotation");
     if (!cutRotationString.empty()) {
diff --git a/dust3d/mesh/mesh_generator.h b/dust3d/mesh/mesh_generator.h
index 6571d84d..48cd9523 100644
--- a/dust3d/mesh/mesh_generator.h
+++ b/dust3d/mesh/mesh_generator.h
@@ -163,6 +163,7 @@ private:
     bool fetchPartOrderedNodes(const std::string &partIdString, std::vector<MeshNode> *meshNodes, bool *isCircle);
 
     static void chamferFace(std::vector<Vector2> *face);
+    static void subdivideFace(std::vector<Vector2> *face);
     static bool isWatertight(const std::vector<std::vector<size_t>> &faces);
     static void flattenLinks(const std::unordered_map<size_t, size_t> &links,
         std::vector<size_t> *array,
diff --git a/dust3d/mesh/tube_mesh_builder.cc b/dust3d/mesh/tube_mesh_builder.cc
index 16b9fec7..5e613370 100644
--- a/dust3d/mesh/tube_mesh_builder.cc
+++ b/dust3d/mesh/tube_mesh_builder.cc
@@ -20,6 +20,7 @@
  *  SOFTWARE.
  */
 
+#include <algorithm>
 #include <dust3d/mesh/base_normal.h>
 #include <dust3d/mesh/tube_mesh_builder.h>
 
@@ -139,6 +140,11 @@ void TubeMeshBuilder::build()
             });
         }
     }
+    if (!m_isCircle) {
+        m_generatedFaces.emplace_back(cutFaceIndices.back());
+        m_generatedFaces.emplace_back(cutFaceIndices.front());
+        std::reverse(m_generatedFaces.back().begin(), m_generatedFaces.back().end());
+    }
 }
 
 }