From f5a70dfd9e9653cd6245733055bb7505e79a0ee4 Mon Sep 17 00:00:00 2001
From: Jeremy Hu <huxingyi@msn.com>
Date: Fri, 9 Aug 2019 19:56:31 +0930
Subject: [PATCH] Segment UV by normal

---
 src/uvunwrap.cpp                             |  7 +++++++
 thirdparty/simpleuv/simpleuv/chartpacker.h   |  1 +
 thirdparty/simpleuv/simpleuv/meshdatatype.h  |  5 ++++-
 thirdparty/simpleuv/simpleuv/uvunwrapper.cpp | 15 +++++++++++++++
 thirdparty/simpleuv/simpleuv/uvunwrapper.h   |  3 +++
 5 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/uvunwrap.cpp b/src/uvunwrap.cpp
index c1993aed..59544d8e 100644
--- a/src/uvunwrap.cpp
+++ b/src/uvunwrap.cpp
@@ -10,6 +10,7 @@ void uvUnwrap(const Outcome &outcome,
 {
     const auto &choosenVertices = outcome.vertices;
     const auto &choosenTriangles = outcome.triangles;
+    const auto &choosenTriangleNormals = outcome.triangleNormals;
     triangleVertexUvs.resize(choosenTriangles.size(), {
         QVector2D(), QVector2D(), QVector2D()
     });
@@ -32,11 +33,17 @@ void uvUnwrap(const Outcome &outcome,
     for (decltype(choosenTriangles.size()) i = 0; i < choosenTriangles.size(); ++i) {
         const auto &triangle = choosenTriangles[i];
         const auto &sourceNode = triangleSourceNodes[i];
+        const auto &normal = choosenTriangleNormals[i];
         simpleuv::Face f;
         f.indices[0] = triangle[0];
         f.indices[1] = triangle[1];
         f.indices[2] = triangle[2];
         inputMesh.faces.push_back(f);
+        simpleuv::Vector3 n;
+        n.xyz[0] = normal.x();
+        n.xyz[1] = normal.y();
+        n.xyz[2] = normal.z();
+        inputMesh.faceNormals.push_back(n);
         auto findPartitionResult = partIdToPartitionMap.find(sourceNode.first);
         if (findPartitionResult == partIdToPartitionMap.end()) {
             partitionPartUuids.push_back(sourceNode.first);
diff --git a/thirdparty/simpleuv/simpleuv/chartpacker.h b/thirdparty/simpleuv/simpleuv/chartpacker.h
index 732a86e2..fd28edce 100644
--- a/thirdparty/simpleuv/simpleuv/chartpacker.h
+++ b/thirdparty/simpleuv/simpleuv/chartpacker.h
@@ -25,6 +25,7 @@ private:
     size_t m_tryNum = 0;
     float m_textureSizeFactor = 1.0;
     size_t m_maxTryNum = 100;
+    float m_texelSizePerUnit = 1.0f;
 };
 
 }
diff --git a/thirdparty/simpleuv/simpleuv/meshdatatype.h b/thirdparty/simpleuv/simpleuv/meshdatatype.h
index 594fc3ed..e83bd17e 100644
--- a/thirdparty/simpleuv/simpleuv/meshdatatype.h
+++ b/thirdparty/simpleuv/simpleuv/meshdatatype.h
@@ -6,11 +6,13 @@
 namespace simpleuv 
 {
 
-struct Vertex
+struct Vector3
 {
     float xyz[3];
 };
 
+typedef Vector3 Vertex;
+
 struct Face
 {
     size_t indices[3];
@@ -30,6 +32,7 @@ struct Mesh
 {
     std::vector<Vertex> vertices;
     std::vector<Face> faces;
+    std::vector<Vector3> faceNormals;
     std::vector<int> facePartitions;
 };
 
diff --git a/thirdparty/simpleuv/simpleuv/uvunwrapper.cpp b/thirdparty/simpleuv/simpleuv/uvunwrapper.cpp
index 1beccd30..d14d50af 100644
--- a/thirdparty/simpleuv/simpleuv/uvunwrapper.cpp
+++ b/thirdparty/simpleuv/simpleuv/uvunwrapper.cpp
@@ -8,6 +8,7 @@
 #include <simpleuv/chartpacker.h>
 #include <simpleuv/triangulate.h>
 #include <QDebug>
+#include <QVector3D>
 
 namespace simpleuv 
 {
@@ -60,6 +61,7 @@ void UvUnwrapper::splitPartitionToIslands(const std::vector<size_t> &group, std:
 {
     std::map<std::pair<size_t, size_t>, size_t> edgeToFaceMap;
     buildEdgeToFaceMap(group, edgeToFaceMap);
+    bool segmentByNormal = !m_mesh.faceNormals.empty() && m_segmentByNormal;
     
     std::unordered_set<size_t> processedFaces;
     std::queue<size_t> waitFaces;
@@ -79,6 +81,12 @@ void UvUnwrapper::splitPartitionToIslands(const std::vector<size_t> &group, std:
                 auto findOppositeFaceResult = edgeToFaceMap.find({face.indices[j], face.indices[i]});
                 if (findOppositeFaceResult == edgeToFaceMap.end())
                     continue;
+                if (segmentByNormal) {
+                    if (dotProduct(m_mesh.faceNormals[findOppositeFaceResult->second],
+                            m_mesh.faceNormals[index]) < m_segmentDotProductThreshold) {
+                        continue;
+                    }
+                }
                 waitFaces.push(findOppositeFaceResult->second);
             }
             island.push_back(index);
@@ -98,6 +106,13 @@ double UvUnwrapper::distanceBetweenVertices(const Vertex &first, const Vertex &s
     return std::sqrt(x*x + y*y + z*z);
 }
 
+double UvUnwrapper::dotProduct(const Vertex &first, const Vertex &second)
+{
+    const QVector3D &firstVector = QVector3D(first.xyz[0], first.xyz[1], first.xyz[2]);
+    const QVector3D &secondVector = QVector3D(second.xyz[0], second.xyz[1], second.xyz[2]);
+    return QVector3D::dotProduct(firstVector, secondVector);
+}
+
 void UvUnwrapper::calculateFaceTextureBoundingBox(const std::vector<FaceTextureCoords> &faceTextureCoords,
         float &left, float &top, float &right, float &bottom)
 {
diff --git a/thirdparty/simpleuv/simpleuv/uvunwrapper.h b/thirdparty/simpleuv/simpleuv/uvunwrapper.h
index 546390bc..ab01b222 100644
--- a/thirdparty/simpleuv/simpleuv/uvunwrapper.h
+++ b/thirdparty/simpleuv/simpleuv/uvunwrapper.h
@@ -37,6 +37,7 @@ private:
     void buildEdgeToFaceMap(const std::vector<size_t> &group, std::map<std::pair<size_t, size_t>, size_t> &edgeToFaceMap);
     void buildEdgeToFaceMap(const std::vector<Face> &faces, std::map<std::pair<size_t, size_t>, size_t> &edgeToFaceMap);
     double distanceBetweenVertices(const Vertex &first, const Vertex &second);
+    double dotProduct(const Vertex &first, const Vertex &second);
     void triangulateRing(const std::vector<Vertex> &verticies,
         std::vector<Face> &faces, const std::vector<size_t> &ring);
     void calculateFaceTextureBoundingBox(const std::vector<FaceTextureCoords> &faceTextureCoords,
@@ -49,6 +50,8 @@ private:
     std::vector<std::pair<float, float>> m_chartSizes;
     std::vector<QRectF> m_chartRects;
     std::vector<int> m_chartSourcePartitions;
+    bool m_segmentByNormal = true;
+    float m_segmentDotProductThreshold = 0.00;
 };
 
 }