Changeset 2614 for GTP/trunk/Lib/Vis/Preprocessing/src

Timestamp:

01/18/08 16:28:30 (16 years ago)

Author:

mattausch

Message:

worked on dynamic objects

Location:

GTP/trunk/Lib/Vis/Preprocessing/src

Files:

• GlRenderer.cpp (modified) (2 diffs)
• Mesh.cpp (modified) (1 diff)
• Mesh.h (modified) (2 diffs)
• MeshKdTree.cpp (modified) (2 diffs)
• Preprocessor.cpp (modified) (9 diffs)
• QtInterface/QtGlRenderer.cpp (modified) (11 diffs)
• QtInterface/QtGlRenderer.h (modified) (6 diffs)
• QtInterface/QtGlViewer.cpp (modified) (2 diffs)
• QtInterface/QtGlViewer.h (modified) (1 diff)
• SamplingStrategy.cpp (modified) (2 diffs)
• ViewCellsManager.cpp (modified) (10 diffs)
• ViewCellsManager.h (modified) (3 diffs)

GTP/trunk/Lib/Vis/Preprocessing/src/GlRenderer.cpp

@@ -368 +368 @@
 
                 Face *face = mesh->mFaces[i];
+                Vector3 normal = mesh->GetNormal(i);
+
+                glNormal3f(normal.x, normal.y, normal.z);
                 for (int j = 0; j < face->mVertexIndices.size(); j++) {
                         glVertex3fv(&mesh->mVertices[face->mVertexIndices[j]].x);
@@ -696 +699 @@
   
   mViewDirection = Normalize(Vector3(sin(dVector.x),
-                                                                         //                                                                      cos(dVector.y),
+                                                                         //     cos(dVector.y),
                                                                          0.0f,
                                                                          cos(dVector.x)));

GTP/trunk/Lib/Vis/Preprocessing/src/Mesh.cpp

@@ -104 +104 @@
                         root->mFaces.push_back(i);
                 
-                cout<<"KD";
+                //cout<<"KD";
+                cout<<"constructed mesh kd tree for " << (int)mFaces.size() << " faces" << endl;
                 
                 mKdTree->Construct();

GTP/trunk/Lib/Vis/Preprocessing/src/Mesh.h

@@ -42 +42 @@
   }
 
-  Face(const VertexIndexContainer &vertices):mVertexIndices(vertices.size()) {
+  Face(const VertexIndexContainer &vertices): mVertexIndices(vertices.size()) {
         for (int i=0;  i < vertices.size(); i++)
           mVertexIndices[i] = vertices[i];
   }
-  
+
+
   ////////////////////////////
 
@@ -178 +179 @@
   int GetId() const { return mId; }
 
-
+  /** Returns normal of specified face.
+  */
   Vector3 GetNormal(const int idx) const;
 

GTP/trunk/Lib/Vis/Preprocessing/src/MeshKdTree.cpp

@@ -147 +147 @@
   vector<int>::const_iterator fi;
   vector<int> objectsFront, objectsBack;
-  
-  for ( fi = leaf->mFaces.begin();
-        fi != leaf->mFaces.end();
-        fi++) {
-    // determine the side of this ray with respect to the plane
-    AxisAlignedBox3 box = mMesh->GetFaceBox(*fi);
-
-    if (box.Max(axis) > position ) 
-      objectsFront.push_back(*fi);
-    
-    if (box.Min(axis) < position )
-      objectsBack.push_back(*fi);
-  }
-  
+
+  for ( fi = leaf->mFaces.begin(); fi != leaf->mFaces.end(); fi++) 
+  {
+          // determine the side of this ray with respect to the plane
+          AxisAlignedBox3 box = mMesh->GetFaceBox(*fi);
+
+          if (box.Max(axis) > position ) 
+                  objectsFront.push_back(*fi);
+
+          if (box.Min(axis) < position )
+                  objectsBack.push_back(*fi);
+  }
+
   MeshKdLeaf *back = new MeshKdLeaf(objectsBack);
   MeshKdLeaf *front = new MeshKdLeaf(objectsFront);
@@ -419 +418 @@
   mRoot = Subdivide(TraversalData(leaf, NULL, GetBox(), 0));
   
+  cout <<  "created " << 
   // remove the allocated array
   delete mSubdivisionCandidates;

GTP/trunk/Lib/Vis/Preprocessing/src/Preprocessor.cpp

@@ -186 +186 @@
         int numTriangles;
 
+        const int t = 500000;
         inStream.read(reinterpret_cast<char *>(&numTriangles), sizeof(int));
         root->mGeometry.reserve(numTriangles);
@@ -209 +210 @@
                 root->mGeometry.push_back(obj);
                 
-                if ((i ++) % 500000 == 499999)
+                if ((i ++) % t == t)
                          cout<<"\r"<<i<<"/"<<numTriangles<<"\r";
         }
@@ -1179 +1180 @@
         // !!!!!!!!!!!!!!!! VH no sorting
         if ( 
-            rays.size() > 10000
+                rays.size() > 10000
                 )
-          {
-          mRayCaster->SortRays(rays);
-          cout<<"Rays sorted in "<<TimeDiff(t1, GetTime())<<" ms."<<endl;
-        }
+        {
+                mRayCaster->SortRays(rays);
+                cout<<"Rays sorted in "<<TimeDiff(t1, GetTime())<<" ms."<<endl;
+        }
+
+        int numTransformed = 0;
 
 
@@ -1208 +1211 @@
 
                 static Ray hRay;
-
                 VssRayContainer::iterator vit, vit_end = vssRays.end();
 
@@ -1219 +1221 @@
 
                         bool foundIntersect = false;
+
                         for (tit = mDynamicObjects.begin(); tit != tit_end; ++ tit)
                         {
                                 TransformedMeshInstance *tmi = *tit;
-                                if (tmi->CastRay(hRay)) //cout << "z"; else cout<< "r";
+
+                                float maxT, minT;
+        
+                                // test with bounding box
+                                if (tmi->GetBox().GetMinMaxT(hRay, &minT, &maxT))
                                 {
-                                        cout << "i: " << Intersectable::GetTypeName(hRay.intersections[0].mObject);
-                                        foundIntersect = true;
+                                        if (tmi->CastRay(hRay)) //cout << "z"; else cout<< "r";
+                                        {
+                                                //cout << "i: " << Intersectable::GetTypeName(hRay.intersections[0].mObject);
+                                                foundIntersect = true;
+                                        }
                                 }
                         }
 
+                        //if (foundIntersect)   cout << "x: " << Intersectable::GetTypeName(hRay.intersections[0].mObject);
+
                         if (foundIntersect)
-                                cout << "x: " << Intersectable::GetTypeName(hRay.intersections[0].mObject);
-
-                        if (foundIntersect)
+                        {
+                                ++ numTransformed;
                                 // write new results back into vssRay
                                 vssRay->Init(hRay);
-
-                        if (foundIntersect)
-                                cout << "y : " << Intersectable::GetTypeName(vssRay->mTerminationObject);
+                        }
 
                         hRay.intersections.clear();
@@ -1258 +1267 @@
 
         }
-        
-        //      cerr<<"Determining PVS objects"<<endl;
+        //cout << "numDummy: " << numTransformed << endl;       
+        //cerr<<"Determining PVS objects"<<endl;
         DeterminePvsObjects(vssRays);
         //      cerr<<"done."<<endl;
@@ -1620 +1629 @@
         cout << "loading " << numTriangles << " triangles into mesh" << endl;
 
-        int i = 0, j = 0;
-
         Mesh *mesh = new Mesh(numTriangles * 3, numTriangles);
 
-        const int t = 500000;
-        while (1)
+        const int t = 1000;
+        for (int j = 0, i = 0; j < numTriangles; ++ j, i += 3)
         {
                 Triangle3 tri;
@@ -1633 +1640 @@
                 inStream.read(reinterpret_cast<char *>(&mesh->mVertices[i + 2]), sizeof(Vector3));
 
-                
-                mesh->mVertices[i].x += 20;
+                /*mesh->mVertices[i].x += 20;
                 mesh->mVertices[i + 1].x += 20;
                 mesh->mVertices[i + 2].x += 20;
@@ -1641 +1647 @@
                 mesh->mVertices[i + 1].z -= 10;
                 mesh->mVertices[i + 2].z -= 10;
-
-                mesh->mVertices[i] *= 50;
-                mesh->mVertices[i + 1] *= 50;
-                mesh->mVertices[i + 2] *= 50;
+*/
+                mesh->mVertices[i] *= 100;
+                mesh->mVertices[i + 1] *= 100;
+                mesh->mVertices[i + 2] *= 100;
 
                 mesh->AddFace(new Face(i + 0, i + 1, i + 2));
 
-                // end of file reached
-                if (inStream.eof())
-                        break;
-
-                i += 3;
-                if (((j ++) % t) == (t - 1))
+                if ((j % t) == (t - 1))
                          cout<<"\r"<<i<<"/"<<numTriangles<<"\r";
         }
-        
-        if (j != numTriangles)
-        {
-                cout << "warning: triangle size does not match with loaded triangle size" << endl;
-                return false;
-        }
+
+        cout << "loaded " << numTriangles << " triangles" << endl;
 
         mesh->Preprocess();
-        cout << "loaded " << numTriangles << " triangles" << endl;
+
+        cout << "finished preprocessing" << endl;
 
         return mesh;

GTP/trunk/Lib/Vis/Preprocessing/src/QtInterface/QtGlRenderer.cpp

@@ -386 +386 @@
         for (dit = mDynamicObjects.begin(); dit != dit_end; ++ dit)
         {
+                //cerr << "here45\n****"<<endl;
                 RenderIntersectable(*dit);
         }
@@ -659 +660 @@
         int diffy = -(mousePoint.y - y);
 
+        const float t = 1.0f;
+
         if (e->modifiers() & Qt::ControlModifier) 
         {
@@ -664 +667 @@
                 mViewPoint.x += (x-mousePoint.x)*MOVE_SENSITIVITY / 2.0;
         } 
-        else 
+        else if (e->modifiers() & Qt::AltModifier)
+        {
+                if (mCurrentDynamicObjectIdx >= 0)
+                {
+                        Matrix4x4 tm;
+                        TransformedMeshInstance *tmi;
+
+                        switch (mTrafoType)
+                        {
+                        case 0:
+                                {
+                                        const Vector3 transl(diffx, 0, diffy);
+                                        tmi = mViewCellsManager->GetPreprocessor()->mDynamicObjects[mCurrentDynamicObjectIdx];
+                                        tm = TranslationMatrix(transl);
+                                }
+                                break;
+                        case 1:
+                                {
+                                        float scalef = 1.0f + 0.01f * (diffx + diffy);
+                                        if (scalef < 0.9) scalef = 0.9f;
+                                        else if (scalef > 1.1f) scalef = 1.1f;
+                                        tmi = mViewCellsManager->GetPreprocessor()->mDynamicObjects[mCurrentDynamicObjectIdx];
+                                        tm = ScaleMatrix(scalef, scalef, scalef);
+                                }
+                                break;
+                        case 2:
+                                {
+                                        tmi = mViewCellsManager->GetPreprocessor()->mDynamicObjects[mCurrentDynamicObjectIdx];
+                                        tm = RotationXMatrix(diffx) * RotationYMatrix(diffy);
+                                }
+                                break;
+                        default:
+                                cerr << "not implemented" << endl;
+                        }
+
+                        tmi->ApplyWorldTransform(tm);
+                        updateGL();
+                }
+        }
+        else
         {
                 mViewPoint += mViewDirection*((mousePoint.y - y)*MOVE_SENSITIVITY);
@@ -889 +931 @@
         mShowWeightedTriangles = false;
         mShowDistribution = 15;
+        mCurrentDynamicObjectIdx = -1;
 
         mSpatialFilterSize = 0.01;
         mPvsSize = 0;
         mRayVisualizationMethod = 0;
+        mTrafoType = 0;
+
         mRenderError = 0.0f;
         mShowRays = false;
@@ -950 +995 @@
         connect(mControlWidget, SIGNAL(SetShowDistribution4(bool)), this, SLOT(SetShowDistribution4(bool)));
 
-
         connect(mControlWidget, SIGNAL(SetShowRays(bool)), this, SLOT(SetShowRays(bool)));
 
+        connect(mControlWidget, SIGNAL(SetTranslation(bool)), this, SLOT(SetTranslation(bool)));
+        connect(mControlWidget, SIGNAL(SetRotation(bool)), this, SLOT(SetRotation(bool)));
+        connect(mControlWidget, SIGNAL(SetScale(bool)), this, SLOT(SetScale(bool)));
+        
         // setting the size here
         resize(800, 600);
@@ -1009 +1057 @@
 void QtGlRendererWidget::LoadObject()
 {
-        string filename("../data/bunny.bn");
+        string filename("../data/teapot.bn");
         
         cout << "Loading model << " << filename << endl;
+
+        ++ mCurrentDynamicObjectIdx;
 
         if (mViewCellsManager->GetPreprocessor()->LoadDynamicGeometry(filename))
@@ -1587 +1637 @@
         
         rb1 = new QRadioButton("random colors", parent);
-        rb1->setText("wireframe");
+        rb1->setText("random");
         connect(rb1, SIGNAL(toggled(bool)), SIGNAL(SetShowWireFrame(bool)));
 
@@ -1627 +1677 @@
 
 
+QGroupBox *QtRendererControlWidget::CreateTrafoPanel(QWidget *parent)
+{
+        QRadioButton *rb1, *rb2, *rb3;
+        
+        rb1 = new QRadioButton("translation", parent);
+        rb1->setText("translation");
+        connect(rb1, SIGNAL(toggled(bool)), SIGNAL(SetTranslation(bool)));
+
+        // Create a check box to be in the group box
+        rb2 = new QRadioButton("scale", parent);
+        rb2->setText("scale");
+        //vl->addWidget(rb1);
+        connect(rb2, SIGNAL(toggled(bool)), SIGNAL(SetScale(bool)));
+
+        rb3 = new QRadioButton("rotation", parent);
+        rb3->setText("rotation");
+        connect(rb3, SIGNAL(toggled(bool)), SIGNAL(SetRotation(bool)));
+    
+        QVBoxLayout *vbox2 = new QVBoxLayout;
+        QGroupBox *groupBox = new QGroupBox("Trafo types");
+
+        vbox2->addWidget(rb1);
+        vbox2->addWidget(rb2);
+        vbox2->addWidget(rb3);
+        
+        rb1->setChecked(true);
+
+        vbox2->addStretch(1);
+        groupBox->setLayout(vbox2);
+
+        return groupBox;
+}
+
+
 
 QGroupBox *QtRendererControlWidget::CreateRenderCostPanel(QWidget *parent)
@@ -1646 +1730 @@
 
         QGroupBox *groupBox = new QGroupBox("Render cost options");
-
         QVBoxLayout *vbox2 = new QVBoxLayout;
     
@@ -1857 +1940 @@
         QGroupBox *groupBox3 = CreateRayVisualizationPanel(hbox);
         vh->addWidget(groupBox3, 0, 0);
+
+        QGroupBox *groupBox4 = CreateTrafoPanel(hbox);
+        vh->addWidget(groupBox4, 0, 0);
 
         //////////////////////////////////
@@ -2032 +2118 @@
         cb->setChecked(false);
         connect(cb, SIGNAL(toggled(bool)), SIGNAL(StoreStatistics()));*/
+
         if (0) 
         {

GTP/trunk/Lib/Vis/Preprocessing/src/QtInterface/QtGlRenderer.h

@@ -91 +91 @@
 
   QGroupBox *CreateVisualizationPanel(QWidget *parent);
+  QGroupBox *CreateTrafoPanel(QWidget *parent);
 
   public slots:
@@ -156 +157 @@
   void SetShowDistribution3(bool);
   void SetShowDistribution4(bool);
+
+  void SetTranslation(bool);
+  void SetRotation(bool);
+  void SetScale(bool);
 };
 
@@ -204 +209 @@
         int mShowDistribution;
 
+        int mCurrentDynamicObjectIdx;
+
         // some statistics
         int mPvsSize;
@@ -214 +221 @@
 
         int mRayVisualizationMethod;
+        int mTrafoType;
 
         QtRendererControlWidget *mControlWidget;
@@ -267 +275 @@
         virtual int GetHeight() const { return height(); }
 
-        // virtual void
-        //  SetupProjection(const int w, const int h, const float angle = 70.0f);
-
         virtual void
                 SetupCameraProjection(const int w, const int h, const float angle = 70.0f);
@@ -479 +484 @@
                 mRayVisualizationMethod = 3;
         }
-        
+
+        void SetTranslation(bool b)
+        {
+                mTrafoType = 0;
+        }
+
+        void SetScale(bool b)
+        {
+                mTrafoType = 1;
+        }
+        
+        void SetRotation(bool b)
+        {
+                mTrafoType = 2;
+        }
+
         void SetShowDistribution1(bool b)
         {

GTP/trunk/Lib/Vis/Preprocessing/src/QtInterface/QtGlViewer.cpp

@@ -242 +242 @@
 QtGlViewer::mouseMoveEvent(QMouseEvent *event)
 {
-  int dx = event->x() - lastPos.x();
-  int dy = event->y() - lastPos.y();  
-  
-  if (event->modifiers() & Qt::CTRL)
-                {
-                        scale = scale*(1.0f - dy/(float)height());
-                        if (scale < 0.01f)
-                                scale = 0.01f;
-                        updateGL();
-                }
-  else {
+        int dx = event->x() - lastPos.x();
+        int dy = event->y() - lastPos.y();  
+
+        if (event->modifiers() & Qt::CTRL)
+        {
+                scale = scale*(1.0f - dy/(float)height());
+                if (scale < 0.01f)
+                        scale = 0.01f;
+                updateGL();
+        }
+        else
+        {
                 float W = width();
                 float H = height();
@@ -259 +260 @@
                 int y = event->y();
                 int lastY = lastPos.y();
-        
+
                 float quat[4];
                 trackball(quat,
-                                  (2.0 * lastX - W) / W,
-                                  (H - 2.0 * lastY) / H,
-                                  (2.0 * x - W) / W,
-                                  (H - 2.0 * y) / H
-                                  );
+                        (2.0 * lastX - W) / W,
+                        (H - 2.0 * lastY) / H,
+                        (2.0 * x - W) / W,
+                        (H - 2.0 * y) / H
+                        );
 
                 add_quats(quat, manipulatorLastQuat, manipulatorLastQuat);
-  }
-  
-  lastPos = event->pos();
-  updateGL();
-}
-
-void QtGlViewer::timerEvent(QTimerEvent *event) 
-{
-        update();
-}
-
-
-}
-
+        }
+
+        lastPos = event->pos();
+        updateGL();
+}
+
+        void QtGlViewer::timerEvent(QTimerEvent *event) 
+        {
+                update();
+        }
+
+
+}
+

GTP/trunk/Lib/Vis/Preprocessing/src/QtInterface/QtGlViewer.h

@@ -58 +58 @@
         float scale;
         QPoint lastPos;
-
 };
 

GTP/trunk/Lib/Vis/Preprocessing/src/SamplingStrategy.cpp

@@ -584 +584 @@
         }
 
+
         for(; it != vssRays.end(); ++it) 
         {
                 VssRay *ray = *it;
 
-                //cout << " here4 " << ray->GetDir();
+                //if (ray->mTerminationObject->Type() == Intersectable::TRANSFORMED_MESH_INSTANCE)
+                //      cout << "found transofrmed mesh instance: " << Intersectable::GetTypeName(ray->mTerminationObject) << " " << endl;
 
                 for (i=0; i < mDistributions.size()-1; i++) 
@@ -596 +598 @@
                 }
 
-                float contribution =
-                        mPreprocessor.mViewCellsManager->ComputeSampleContribution(*ray,
-                        true,
-                        false);
+                const float contribution =
+                        mPreprocessor.mViewCellsManager->ComputeSampleContribution(*ray, true, false);
 
                 mDistributions[i]->mContribution += contribution;

GTP/trunk/Lib/Vis/Preprocessing/src/ViewCellsManager.cpp

@@ -2407 +2407 @@
                                                                                                    Intersectable *obj,
                                                                                                    const Vector3 &pt,
-                                                                                                   const bool addSamplesToPvs)
+                                                                                                   bool addSamplesToPvs)
 {
         // check if we are outside of view space
@@ -2424 +2424 @@
         if (addSamplesToPvs) 
         {
+                //if (obj->Type() == Intersectable::TRANSFORMED_MESH_INSTANCE)cout << "here12 " << endl;
+
                 hasAbsContribution = viewCell->GetPvs().AddSampleDirtyCheck(obj, ray.mPdf);
                 //hasAbsContribution = viewCell->GetPvs().AddSample(obj,ray.mPdf);
@@ -2437 +2439 @@
                         viewCell->GetPvs().GetSampleContribution(obj, ray.mPdf, relContribution);
         }
-
-        //cout << "here6: " << ray.GetDir() << " ";
 
         // $$ clear the relative contribution as it is currently not correct anyway
@@ -2483 +2483 @@
 
 void
-ViewCellsManager::DeterminePvsObjects(
-                                                                          VssRayContainer &rays,
-                                                                          const bool useHitObjects)
+ViewCellsManager::DeterminePvsObjects(VssRayContainer &rays,
+                                                                          bool useHitObjects)
 {
         if (!useHitObjects) 
@@ -2498 +2497 @@
                         // set only the termination object
                         vssRay->mTerminationObject = GetIntersectable(*vssRay, true);
+                        
+                        if (vssRay->mTerminationObject->Type() == Intersectable::TRANSFORMED_MESH_INSTANCE)     
+                                cout << "r";
+
 #if 0
-                  if (vssRay->mTerminationObject == NULL) {
-                        cerr<<"Error in DeterminePvsObjects - termination object maps to NULL!"<<endl;
-                  }
+                  if (vssRay->mTerminationObject == NULL)
+                          cerr<<"Error in DeterminePvsObjects - termination object maps to NULL!"<<endl;
 #endif
                 }
         }
-  
 }
 
@@ -2547 +2548 @@
 float
 ViewCellsManager::ComputeSampleContribution(VssRay &ray,
-                                                                                        const bool addRays,
-                                                                                        const bool storeViewCells,
-                                                                                        const bool useHitObjects)
+                                                                                        bool addRays,
+                                                                                        bool storeViewCells,
+                                                                                        bool useHitObjects)
 {
         ray.mPvsContribution = 0;
@@ -2595 +2596 @@
                 // traverse the view space subdivision
                 CastLineSegment(origin, termination, viewCells);
-
                 lastVssRay = &ray;
         }
@@ -2631 +2631 @@
         pvsTimer.Entry();
 #endif
-        
+        //if (terminationObj->Type() == Intersectable::TRANSFORMED_MESH_INSTANCE)
+        //      cout << "found tmi: " << Intersectable::GetTypeName(terminationObj) << " " << viewCells.size() << endl;
         bool contri = false;
         ViewCellContainer::const_iterator it = viewCells.begin();
@@ -2638 +2639 @@
         {
                 if (ComputeViewCellContribution(*it, 
-                                                ray, 
-                                                                        terminationObj, 
-                                                                        ray.mTermination, 
-                                                                        addRays))
+                                                    ray, 
+                                                                                terminationObj, 
+                                                                                ray.mTermination, 
+                                                                                addRays))
                 {
                         contri = true;
@@ -3166 +3167 @@
 void ViewCellsManager::MergeViewCellsRecursivly(ObjectPvs &pvs, 
                                                                                                 const ViewCellContainer &viewCells, 
-                                                                                                const int leftIdx, 
-                                                                                                const int rightIdx) const
+                                                                                                int leftIdx, 
+                                                                                                int rightIdx) const
 {
         if (leftIdx == rightIdx)

GTP/trunk/Lib/Vis/Preprocessing/src/ViewCellsManager.h

@@ -206 +206 @@
         */
         virtual float ComputeSampleContribution(VssRay &ray, 
-                                                                                        const bool addContributions,
-                                                                                        const bool storeViewCells,
-                                                                                        const bool useHitObject = false);
+                                                                                        bool addContributions,
+                                                                                        bool storeViewCells,
+                                                                                        bool useHitObject = false);
         /** Compute sample contribution only for current view cell.
         */
@@ -388 +388 @@
         */
         void DeterminePvsObjects(VssRayContainer &rays,
-                                                         const bool useHitObjects = false);
+                                                         bool useHitObjects = false);
         /** Sets validity of view cell
         */
@@ -640 +640 @@
                                                                          Intersectable *obj,
                                                                          const Vector3 &pt,
-                                                                         const bool addRays);
+                                                                         bool addRays);
 
         void MergeViewCellsRecursivly(ObjectPvs &pvs, 
                                                                   const ViewCellContainer &viewCells, 
-                                                                  const int leftIdx, 
-                                                                  const int rightIdx) const;
+                                                                  int leftIdx, 
+                                                                  int rightIdx) const;
+
         /** Intersects box with the tree and returns the number of intersected boxes.
                 @returns number of view cells found