diff --git a/src/mesh.cpp b/src/mesh.cpp
index 8367d520..55309453 100644
--- a/src/mesh.cpp
+++ b/src/mesh.cpp
@@ -5,11 +5,12 @@
 
 #define MAX_VERTICES_PER_FACE   100
 
-Mesh::Mesh(void *meshlite, int meshId) :
+Mesh::Mesh(void *meshlite, int meshId, bool broken) :
     m_triangleVertices(NULL),
     m_triangleVertexCount(0),
     m_edgeVertices(NULL),
-    m_edgeVertexCount(0)
+    m_edgeVertexCount(0),
+    m_broken(broken)
 {
     int edgeVertexPositionCount = meshlite_get_vertex_count(meshlite, meshId);
     GLfloat *edgeVertexPositions = new GLfloat[edgeVertexPositionCount * 3];
@@ -82,6 +83,11 @@ Mesh::Mesh(void *meshlite, int meshId) :
     float modelR = Theme::white.redF();
     float modelG = Theme::white.greenF();
     float modelB = Theme::white.blueF();
+    if (m_broken) {
+        modelR = 1.0;
+        modelG = 1.0;
+        modelB = 1.0;
+    }
     m_triangleVertexCount = triangleCount * 3;
     m_triangleVertices = new Vertex[m_triangleVertexCount * 3];
     for (int i = 0; i < triangleCount; i++) {
@@ -119,6 +125,11 @@ Mesh::~Mesh()
     m_triangleVertexCount = 0;
 }
 
+void Mesh::setBroken(bool broken)
+{
+    m_broken = broken;
+}
+
 const std::vector<QVector3D> &Mesh::vertices()
 {
     return m_vertices;
diff --git a/src/mesh.h b/src/mesh.h
index fb3a64a6..d8ce90d3 100644
--- a/src/mesh.h
+++ b/src/mesh.h
@@ -24,7 +24,7 @@ typedef struct
 class Mesh
 {
 public:
-    Mesh(void *meshlite, int meshId);
+    Mesh(void *meshlite, int meshId, bool broken=false);
     ~Mesh();
     Vertex *triangleVertices();
     int triangleVertexCount();
@@ -32,6 +32,7 @@ public:
     int edgeVertexCount();
     const std::vector<QVector3D> &vertices();
     const std::vector<std::vector<int>> &faces();
+    void setBroken(bool broken);
 private:
     Vertex *m_triangleVertices;
     int m_triangleVertexCount;
@@ -39,6 +40,7 @@ private:
     int m_edgeVertexCount;
     std::vector<QVector3D> m_vertices;
     std::vector<std::vector<int>> m_faces;
+    bool m_broken;
 };
 
 #endif
diff --git a/src/meshgenerator.cpp b/src/meshgenerator.cpp
index bf0b4b0c..e47bef76 100644
--- a/src/meshgenerator.cpp
+++ b/src/meshgenerator.cpp
@@ -8,6 +8,8 @@
 #include "meshutil.h"
 #include "theme.h"
 
+bool MeshGenerator::enableDebug = false;
+
 MeshGenerator::MeshGenerator(SkeletonSnapshot *snapshot, QThread *thread) :
     m_snapshot(snapshot),
     m_mesh(nullptr),
@@ -75,34 +77,46 @@ QImage *MeshGenerator::takePartPreview(const QString &partId)
 
 void MeshGenerator::resolveBoundingBox(QRectF *mainProfile, QRectF *sideProfile)
 {
-    float left = -1;
-    float right = -1;
-    float top = -1;
-    float bottom = -1;
-    float zLeft = -1;
-    float zRight = -1;
+    float left = 0;
+    bool leftFirstTime = true;
+    float right = 0;
+    bool rightFirstTime = true;
+    float top = 0;
+    bool topFirstTime = true;
+    float bottom = 0;
+    bool bottomFirstTime = true;
+    float zLeft = 0;
+    bool zLeftFirstTime = true;
+    float zRight = 0;
+    bool zRightFirstTime = true;
     for (const auto &nodeIt: m_snapshot->nodes) {
         float radius = valueOfKeyInMapOrEmpty(nodeIt.second, "radius").toFloat();
         float x = valueOfKeyInMapOrEmpty(nodeIt.second, "x").toFloat();
         float y = valueOfKeyInMapOrEmpty(nodeIt.second, "y").toFloat();
         float z = valueOfKeyInMapOrEmpty(nodeIt.second, "z").toFloat();
-        if (left < 0 || x - radius < left) {
+        if (leftFirstTime || x - radius < left) {
             left = x - radius;
+            leftFirstTime = false;
         }
-        if (top < 0 || y - radius < top) {
+        if (topFirstTime || y - radius < top) {
             top = y - radius;
+            topFirstTime = false;
         }
-        if (x + radius > right) {
+        if (rightFirstTime > right) {
             right = x + radius;
+            rightFirstTime = false;
         }
-        if (y + radius > bottom) {
+        if (bottomFirstTime > bottom) {
             bottom = y + radius;
+            bottomFirstTime = false;
         }
-        if (zLeft < 0 || z - radius < zLeft) {
+        if (zLeftFirstTime || z - radius < zLeft) {
             zLeft = z - radius;
+            zLeftFirstTime = false;
         }
-        if (z + radius > zRight) {
+        if (zRightFirstTime > zRight) {
             zRight = z + radius;
+            zRightFirstTime = false;
         }
     }
     *mainProfile = QRectF(left, top, right - left, bottom - top);
@@ -117,7 +131,6 @@ void MeshGenerator::process()
     void *meshliteContext = meshlite_create_context();
     std::map<QString, int> partBmeshMap;
     std::map<QString, int> bmeshNodeMap;
-    bool hasSubdiv = false;
     
     QRectF mainProfile, sideProfile;
     resolveBoundingBox(&mainProfile, &sideProfile);
@@ -132,6 +145,8 @@ void MeshGenerator::process()
     
     for (const auto &partIdIt: m_snapshot->partIdList) {
         int bmeshId = meshlite_bmesh_create(meshliteContext);
+        if (MeshGenerator::enableDebug)
+            meshlite_bmesh_enable_debug(meshliteContext, bmeshId, 1);
         partBmeshMap[partIdIt] = bmeshId;
     }
     
@@ -200,39 +215,65 @@ void MeshGenerator::process()
         bmeshNodeMap[nodeIt.first] = bmeshNodeId;
     }
     
-    std::map<QString, int> partMeshMap;
     std::vector<int> meshIds;
+    std::vector<int> subdivMeshIds;
     for (const auto &partIdIt: m_snapshot->partIdList) {
         const auto part = m_snapshot->parts.find(partIdIt);
         int bmeshId = partBmeshMap[partIdIt];
-        int meshId = meshlite_bmesh_generate_mesh(meshliteContext, bmeshId, 0);
-        if (isTrueValueString(part->second["subdived"])) {
-            int subdivedMeshId = subdivMesh(meshliteContext, meshId);
-            if (subdivedMeshId > 0) {
-                meshId = subdivedMeshId;
-                hasSubdiv = true;
-            }
-        }
+        int meshId = meshlite_bmesh_generate_mesh(meshliteContext, bmeshId);
+        bool subdived = isTrueValueString(part->second["subdived"]);
         if (m_requirePartPreviewMap.find(partIdIt) != m_requirePartPreviewMap.end()) {
             ModelOfflineRender *render = m_partPreviewRenderMap[partIdIt];
             int trimedMeshId = meshlite_trim(meshliteContext, meshId, 1);
+            if (subdived) {
+                int subdivedMeshId = subdivMesh(meshliteContext, trimedMeshId);
+                if (subdivedMeshId > 0) {
+                    trimedMeshId = subdivedMeshId;
+                }
+            }
             render->updateMesh(new Mesh(meshliteContext, trimedMeshId));
             QImage *image = new QImage(render->toImage(QSize(Theme::previewImageSize, Theme::previewImageSize)));
             m_partPreviewMap[partIdIt] = image;
         }
-        int triangulatedMeshId = meshlite_triangulate(meshliteContext, meshId);
-        meshIds.push_back(triangulatedMeshId);
+        if (subdived)
+            subdivMeshIds.push_back(meshId);
+        else
+            meshIds.push_back(meshId);
+    }
+    
+    bool broken = false;
+    if (!subdivMeshIds.empty()) {
+        int mergedMeshId = 0;
+        int errorCount = 0;
+        mergedMeshId = unionMeshs(meshliteContext, subdivMeshIds, &errorCount);
+        if (errorCount)
+            broken = true;
+        else if (mergedMeshId > 0)
+            mergedMeshId = meshlite_combine_coplanar_faces(meshliteContext, mergedMeshId);
+        if (mergedMeshId > 0) {
+            int subdivedMeshId = subdivMesh(meshliteContext, mergedMeshId);
+            if (subdivedMeshId > 0)
+                mergedMeshId = subdivedMeshId;
+            else
+                broken = true;
+        }
+        if (mergedMeshId > 0)
+            meshIds.push_back(mergedMeshId);
+        else
+            broken = true;
     }
     
     int mergedMeshId = 0;
     if (meshIds.size() > 1) {
-        mergedMeshId = unionMeshs(meshliteContext, meshIds);
+        int errorCount = 0;
+        mergedMeshId = unionMeshs(meshliteContext, meshIds, &errorCount);
+        if (errorCount)
+            broken = true;
+        else if (mergedMeshId > 0)
+            mergedMeshId = meshlite_combine_coplanar_faces(meshliteContext, mergedMeshId);
     } else if (meshIds.size() > 0) {
         mergedMeshId = meshIds[0];
     }
-    if (mergedMeshId > 0 && !hasSubdiv) {
-        mergedMeshId = meshlite_combine_coplanar_faces(meshliteContext, mergedMeshId);
-    }
     
     if (mergedMeshId > 0) {
         if (m_requirePreview) {
@@ -241,7 +282,7 @@ void MeshGenerator::process()
             m_preview = image;
         }
         int trimedMeshId = meshlite_trim(meshliteContext, mergedMeshId, 1);
-        m_mesh = new Mesh(meshliteContext, trimedMeshId);
+        m_mesh = new Mesh(meshliteContext, trimedMeshId, broken);
     }
     
     if (m_previewRender) {
diff --git a/src/meshgenerator.h b/src/meshgenerator.h
index 42f9a8e5..0699c019 100644
--- a/src/meshgenerator.h
+++ b/src/meshgenerator.h
@@ -37,6 +37,7 @@ private:
     QThread *m_thread;
 private:
     void resolveBoundingBox(QRectF *mainProfile, QRectF *sideProfile);
+    static bool enableDebug;
 };
 
 #endif
diff --git a/src/meshutil.cpp b/src/meshutil.cpp
index 72f5ba04..7cfd4458 100644
--- a/src/meshutil.cpp
+++ b/src/meshutil.cpp
@@ -139,7 +139,7 @@ ExactMesh *unionCgalMeshs(ExactMesh *first, ExactMesh *second)
 
 #endif
 
-int unionMeshs(void *meshliteContext, const std::vector<int> &meshIds)
+int unionMeshs(void *meshliteContext, const std::vector<int> &meshIds, int *errorCount)
 {
 #if USE_CGAL == 1
     CGAL::set_error_behaviour(CGAL::THROW_EXCEPTION);
@@ -158,14 +158,13 @@ int unionMeshs(void *meshliteContext, const std::vector<int> &meshIds)
             try {
                 unionedExternalMesh = unionCgalMeshs(mergedExternalMesh, externalMeshs[i]);
             } catch (...) {
-                // ignore;
+                if (errorCount)
+                    (*errorCount)++;
             }
             delete externalMeshs[i];
             if (unionedExternalMesh) {
                 delete mergedExternalMesh;
                 mergedExternalMesh = unionedExternalMesh;
-            } else {
-                // TOOD:
             }
         }
         if (mergedExternalMesh) {
@@ -199,7 +198,7 @@ int subdivMesh(void *meshliteContext, int meshId)
 //    return makeMeshliteMeshFromCgal<SimpleKernel>(meshliteContext, simpleMesh);
 //#else
     if (0 == meshlite_is_triangulated_manifold(meshliteContext, triangulatedMeshId)) {
-        return meshId;
+        return 0;
     }
     return meshlite_subdivide(meshliteContext, meshId);
 //#endif
diff --git a/src/meshutil.h b/src/meshutil.h
index f4ef67ee..a2cfcd46 100644
--- a/src/meshutil.h
+++ b/src/meshutil.h
@@ -3,7 +3,7 @@
 #include <vector>
 
 int mergeMeshs(void *meshliteContext, const std::vector<int> &meshIds);
-int unionMeshs(void *meshliteContext, const std::vector<int> &meshIds);
+int unionMeshs(void *meshliteContext, const std::vector<int> &meshIds, int *errorCount=0);
 int subdivMesh(void *meshliteContext, int meshId);
 
 #endif