// @(#):$Id$
// Author: Andrei Gheata   30/05/02
// TGeoBoolNode::Contains and parser implemented by Mihaela Gheata

   
/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
#include "TGeoBoolNode.h"

#include "Riostream.h"

#include "TThread.h"
#include "TVirtualPad.h"
#include "TVirtualViewer3D.h"
#include "TBuffer3D.h"
#include "TBuffer3DTypes.h"
#include "TMath.h"
#include "TGeoCompositeShape.h"
#include "TGeoMatrix.h"
#include "TGeoManager.h"

//_____________________________________________________________________________
//  TGeoBoolNode - base class for Boolean operations between two shapes.
//===============
// A Boolean node describes a Boolean operation between 'left' and 'right' 
// shapes positioned with respect to an ARBITRARY reference frame. The boolean
// node is referenced by a mother composite shape and its shape components may
// be primitive but also composite shapes. The later situation leads to a binary
// tree hierarchy. When the parent composite shape is used to create a volume,
// the reference frame of the volume is chosen to match the frame in which 
// node shape components were defined.
//
// The positioned shape components may or may not be disjoint. The specific 
// implementations for Boolean nodes are:
//
//    TGeoUnion - representing the Boolean  union of two positioned shapes
//
//    TGeoSubtraction - representing the Boolean subtraction of two positioned 
//                shapes
// 
//    TGeoIntersection - representing the Boolean intersection of two positioned
//                shapes
//_____________________________________________________________________________

ClassImp(TGeoBoolNode)

//______________________________________________________________________________
TGeoBoolNode::ThreadData_t::ThreadData_t() :
   fSelected(0)
{
   // Constructor.
}

//______________________________________________________________________________
TGeoBoolNode::ThreadData_t::~ThreadData_t()
{
   // Destructor.
}

//______________________________________________________________________________
TGeoBoolNode::ThreadData_t& TGeoBoolNode::GetThreadData() const
{
   Int_t tid = TGeoManager::ThreadId();
/*
   TThread::Lock();
   if (tid >= fThreadSize) {
      Error("GetThreadData", "Thread id=%d bigger than maximum declared thread number %d. \nUse TGeoManager::SetMaxThreads properly !!!",
             tid, fThreadSize);
   }          
   if (tid >= fThreadSize)
   {
      fThreadData.resize(tid + 1);
      fThreadSize = tid + 1;
   }
   if (fThreadData[tid] == 0)
   {
   if (fThreadData[tid] == 0)
      fThreadData[tid] = new ThreadData_t;
   }   
   TThread::UnLock();
*/
   return *fThreadData[tid];
}

//______________________________________________________________________________
void TGeoBoolNode::ClearThreadData() const
{
   TThread::Lock();
   std::vector<ThreadData_t*>::iterator i = fThreadData.begin();
   while (i != fThreadData.end())
   {
      delete *i;
      ++i;
   }
   fThreadData.clear();
   fThreadSize = 0;
   TThread::UnLock();
}

//______________________________________________________________________________
void TGeoBoolNode::CreateThreadData(Int_t nthreads)
{
// Create thread data for n threads max.
   TThread::Lock();
   fThreadData.resize(nthreads);
   fThreadSize = nthreads;
   for (Int_t tid=0; tid<nthreads; tid++) {
      if (fThreadData[tid] == 0) {
         fThreadData[tid] = new ThreadData_t;
      }
   }   
   // Propagate to components
   if (fLeft)  fLeft->CreateThreadData(nthreads);
   if (fRight) fRight->CreateThreadData(nthreads);
   TThread::UnLock();
}

//______________________________________________________________________________
void TGeoBoolNode::SetSelected(Int_t sel)
{
   // Set the selected branch.

   GetThreadData().fSelected = sel;
}

//______________________________________________________________________________
TGeoBoolNode::TGeoBoolNode()
{
// Default constructor
   fLeft     = 0;
   fRight    = 0;
   fLeftMat  = 0;
   fRightMat = 0;
   fNpoints  = 0;
   fPoints   = 0;
   fThreadSize = 0;
   CreateThreadData(1);
}

//______________________________________________________________________________
TGeoBoolNode::TGeoBoolNode(const char *expr1, const char *expr2)
{
// Constructor called by TGeoCompositeShape providing 2 subexpressions for the 2 branches.
   fLeft     = 0;
   fRight    = 0;
   fLeftMat  = 0;
   fRightMat = 0;
   fNpoints  = 0;
   fPoints   = 0;
   fThreadSize = 0;
   CreateThreadData(1);
   if (!MakeBranch(expr1, kTRUE)) {
      return;
   }
   if (!MakeBranch(expr2, kFALSE)) {
      return;
   }
}

//______________________________________________________________________________
TGeoBoolNode::TGeoBoolNode(TGeoShape *left, TGeoShape *right, TGeoMatrix *lmat, TGeoMatrix *rmat)
{
// Constructor providing left and right shapes and matrices (in the Boolean operation).
   fLeft = left;
   fRight = right;
   fLeftMat = lmat;
   fNpoints  = 0;
   fPoints   = 0;
   fThreadSize = 0;
   CreateThreadData(1);
   if (!fLeftMat) fLeftMat = gGeoIdentity;
   else fLeftMat->RegisterYourself();
   fRightMat = rmat;
   if (!fRightMat) fRightMat = gGeoIdentity;
   else fRightMat->RegisterYourself();
   if (!fLeft) {
      Error("ctor", "left shape is NULL");
      return;
   }   
   if (!fRight) {
      Error("ctor", "right shape is NULL");
      return;
   }   
}

//______________________________________________________________________________
TGeoBoolNode::~TGeoBoolNode()
{
// Destructor.
// --- deletion of components handled by TGeoManager class.
   if (fPoints) delete [] fPoints;
   ClearThreadData();
}

//______________________________________________________________________________
Bool_t TGeoBoolNode::MakeBranch(const char *expr, Bool_t left)
{
// Expands the boolean expression either on left or right branch, creating
// component elements (composite shapes and boolean nodes). Returns true on success.
   TString sleft, sright, stransf;
   Int_t boolop = TGeoManager::Parse(expr, sleft, sright, stransf);
   if (boolop<0) {
      Error("MakeBranch", "invalid expression");
      return kFALSE;
   }
   TGeoShape *shape = 0;
   TGeoMatrix *mat;
   TString newshape;

   if (stransf.Length() == 0) {
      mat = gGeoIdentity;
   } else {   
      mat = (TGeoMatrix*)gGeoManager->GetListOfMatrices()->FindObject(stransf.Data());    
   }
   if (!mat) {
      Error("MakeBranch", "transformation %s not found", stransf.Data());
      return kFALSE;
   }
   switch (boolop) {
      case 0:
         // elementary shape
         shape = (TGeoShape*)gGeoManager->GetListOfShapes()->FindObject(sleft.Data()); 
         if (!shape) {
            Error("MakeBranch", "shape %s not found", sleft.Data());
            return kFALSE;
         }
         break;
      case 1:
         // composite shape - union
         newshape = sleft;
         newshape += "+";
         newshape += sright;
         shape = new TGeoCompositeShape(newshape.Data());
         break;
      case 2:
         // composite shape - difference
         newshape = sleft;
         newshape += "-";
         newshape += sright;
         shape = new TGeoCompositeShape(newshape.Data());
         break;
      case 3:
         // composite shape - intersection
         newshape = sleft;
         newshape += "*";
         newshape += sright;
         shape = new TGeoCompositeShape(newshape.Data());
         break;
   }      
   if (boolop && (!shape || !shape->IsValid())) {
      Error("MakeBranch", "Shape %s not valid", newshape.Data());
      if (shape) delete shape;
      return kFALSE;
   }      
   if (left) {
      fLeft = shape;
      fLeftMat = mat;
   } else {
      fRight = shape;
      fRightMat = mat;
   }
   return kTRUE;                  
}

//______________________________________________________________________________
void TGeoBoolNode::Paint(Option_t * option)
{
// Special schema for feeding the 3D buffers to the painter client.
   TVirtualViewer3D * viewer = gPad->GetViewer3D();
   if (!viewer) return;

   // Components of composite shape hierarchies for local frame viewers are painted 
   // in coordinate frame of the top level composite shape. So we force 
   // conversion to this.  See TGeoPainter::PaintNode for loading of GLMatrix.
   Bool_t localFrame = kFALSE; //viewer->PreferLocalFrame();

   TGeoHMatrix *glmat = (TGeoHMatrix*)TGeoShape::GetTransform();
   TGeoHMatrix mat;
   mat = glmat; // keep a copy

   // Now perform fetch and add of the two components buffers.
   // Note we assume that composite shapes are always completely added
   // so don't bother to get addDaughters flag from viewer->AddObject()

   // Setup matrix and fetch/add the left component buffer
   glmat->Multiply(fLeftMat);
   //fLeft->Paint(option);
   if (TGeoCompositeShape *left = dynamic_cast<TGeoCompositeShape *>(fLeft)) left->PaintComposite(option);
   else {
      const TBuffer3D & leftBuffer = fLeft->GetBuffer3D(TBuffer3D::kAll, localFrame);
      viewer->AddObject(leftBuffer);
   }

   // Setup matrix and fetch/add the right component buffer
   *glmat = &mat;
   glmat->Multiply(fRightMat);
   //fRight->Paint(option);
   if (TGeoCompositeShape *right = dynamic_cast<TGeoCompositeShape *>(fRight)) right->PaintComposite(option);
   else {
      const TBuffer3D & rightBuffer = fRight->GetBuffer3D(TBuffer3D::kAll, localFrame);
      viewer->AddObject(rightBuffer);
   }

   *glmat = &mat;   
}

//_____________________________________________________________________________
void TGeoBoolNode::RegisterMatrices()
{
// Register all matrices of the boolean node and descendents.
   if (!fLeftMat->IsIdentity()) fLeftMat->RegisterYourself();   
   if (!fRightMat->IsIdentity()) fRightMat->RegisterYourself();   
   if (fLeft->IsComposite()) ((TGeoCompositeShape*)fLeft)->GetBoolNode()->RegisterMatrices();
   if (fRight->IsComposite()) ((TGeoCompositeShape*)fRight)->GetBoolNode()->RegisterMatrices();
}

//_____________________________________________________________________________
Bool_t TGeoBoolNode::ReplaceMatrix(TGeoMatrix *mat, TGeoMatrix *newmat)
{
// Replace one of the matrices. Does not work with TGeoIdentity. Returns true
// if replacement was successful.
   if (mat==gGeoIdentity || newmat==gGeoIdentity) {
      Error("ReplaceMatrix", "Matrices should not be gGeoIdentity. Use default matrix constructor to repersent identities.");
      return kFALSE;
   }
   if (!mat || !newmat) {
      Error("ReplaceMatrix", "Matrices should not be null pointers.");
      return kFALSE;
   }
   Bool_t replaced = kFALSE;
   if (fLeftMat == mat) {
      fLeftMat  = newmat;
      replaced = kTRUE;
   }
   if (fRightMat == mat) {
      fRightMat  = newmat;
      replaced = kTRUE;
   }
   return replaced;
}

//_____________________________________________________________________________
void TGeoBoolNode::SavePrimitive(std::ostream &out, Option_t *option /*= ""*/)
{
// Save a primitive as a C++ statement(s) on output stream "out".
   fLeft->SavePrimitive(out,option);
   fRight->SavePrimitive(out,option);
   if (!fLeftMat->IsIdentity()) {
      fLeftMat->RegisterYourself();
      fLeftMat->SavePrimitive(out,option);
   }      
   if (!fRightMat->IsIdentity()) {
      fRightMat->RegisterYourself();
      fRightMat->SavePrimitive(out,option);
   }      
}

//______________________________________________________________________________
void TGeoBoolNode::SetPoints(Double_t *points) const
{
// Fill buffer with shape vertices.
   TGeoBoolNode *bn = (TGeoBoolNode*)this;
   Int_t npoints = bn->GetNpoints();
   memcpy(points, fPoints, 3*npoints*sizeof(Double_t));
}

//______________________________________________________________________________
void TGeoBoolNode::SetPoints(Float_t *points) const
{
// Fill buffer with shape vertices.
   TGeoBoolNode *bn = (TGeoBoolNode*)this;
   Int_t npoints = bn->GetNpoints();
   for (Int_t i=0; i<3*npoints; i++) points[i] = fPoints[i];
}

//______________________________________________________________________________
void TGeoBoolNode::Sizeof3D() const
{
// Register size of this 3D object
   fLeft->Sizeof3D();
   fRight->Sizeof3D();
}

ClassImp(TGeoUnion)

//______________________________________________________________________________
TGeoBoolNode *TGeoUnion::MakeClone() const
{
// Make a clone of this. Pointers are preserved.
   return new TGeoUnion(fLeft, fRight, fLeftMat, fRightMat);
}   

//______________________________________________________________________________
void TGeoUnion::Paint(Option_t *option)
{
// Paint method.
   TVirtualViewer3D *viewer = gPad->GetViewer3D();

   if (!viewer) {
      Error("Paint", "gPad->GetViewer3D() returned 0, cannot work with composite!\n");
      return;
   }

   viewer->AddCompositeOp(TBuffer3D::kCSUnion);

   TGeoBoolNode::Paint(option);
}

//______________________________________________________________________________
TGeoUnion::TGeoUnion()
{
// Default constructor
}

//______________________________________________________________________________
TGeoUnion::TGeoUnion(const char *expr1, const char *expr2)
          :TGeoBoolNode(expr1, expr2)
{
// Constructor
}

//______________________________________________________________________________
TGeoUnion::TGeoUnion(TGeoShape *left, TGeoShape *right, TGeoMatrix *lmat, TGeoMatrix *rmat)
          :TGeoBoolNode(left,right,lmat,rmat)
{
// Constructor providing pointers to components
   if (left->TestShapeBit(TGeoShape::kGeoHalfSpace) || right->TestShapeBit(TGeoShape::kGeoHalfSpace)) {
      Fatal("TGeoUnion", "Unions with a half-space (%s + %s) not allowed", left->GetName(), right->GetName());
   }
}

//______________________________________________________________________________
TGeoUnion::~TGeoUnion()
{
// Destructor
// --- deletion of components handled by TGeoManager class.
}

//______________________________________________________________________________
void TGeoUnion::ComputeBBox(Double_t &dx, Double_t &dy, Double_t &dz, Double_t *origin)
{
// Compute bounding box corresponding to a union of two shapes.
   if (((TGeoBBox*)fLeft)->IsNullBox()) fLeft->ComputeBBox();
   if (((TGeoBBox*)fRight)->IsNullBox()) fRight->ComputeBBox();
   Double_t vert[48];
   Double_t pt[3];
   Int_t i;
   Double_t xmin, xmax, ymin, ymax, zmin, zmax;
   xmin = ymin = zmin = TGeoShape::Big();
   xmax = ymax = zmax = -TGeoShape::Big();
   ((TGeoBBox*)fLeft)->SetBoxPoints(&vert[0]);
   ((TGeoBBox*)fRight)->SetBoxPoints(&vert[24]);
   for (i=0; i<8; i++) {
      fLeftMat->LocalToMaster(&vert[3*i], &pt[0]);
      if (pt[0]<xmin) xmin=pt[0];
      if (pt[0]>xmax) xmax=pt[0];
      if (pt[1]<ymin) ymin=pt[1];
      if (pt[1]>ymax) ymax=pt[1];
      if (pt[2]<zmin) zmin=pt[2];
      if (pt[2]>zmax) zmax=pt[2];
   }   
   for (i=8; i<16; i++) {
      fRightMat->LocalToMaster(&vert[3*i], &pt[0]);
      if (pt[0]<xmin) xmin=pt[0];
      if (pt[0]>xmax) xmax=pt[0];
      if (pt[1]<ymin) ymin=pt[1];
      if (pt[1]>ymax) ymax=pt[1];
      if (pt[2]<zmin) zmin=pt[2];
      if (pt[2]>zmax) zmax=pt[2];
   }   
   dx = 0.5*(xmax-xmin);
   origin[0] = 0.5*(xmin+xmax);
   dy = 0.5*(ymax-ymin);
   origin[1] = 0.5*(ymin+ymax);
   dz = 0.5*(zmax-zmin);
   origin[2] = 0.5*(zmin+zmax);
}

//______________________________________________________________________________
Bool_t TGeoUnion::Contains(const Double_t *point) const
{
// Find if a union of two shapes contains a given point
   Double_t local[3];
   fLeftMat->MasterToLocal(point, &local[0]);
   Bool_t inside = fLeft->Contains(&local[0]);
   if (inside) return kTRUE;
   fRightMat->MasterToLocal(point, &local[0]);
   inside = fRight->Contains(&local[0]);
   return inside;
}

//_____________________________________________________________________________
void TGeoUnion::ComputeNormal(const Double_t *point, const Double_t *dir, Double_t *norm)
{
// Normal computation in POINT. The orientation is chosen so that DIR.dot.NORM>0.
   ThreadData_t& td = GetThreadData();
   norm[0] = norm[1] = 0.;
   norm[2] = 1.;
   Double_t local[3];
   Double_t ldir[3], lnorm[3];
   if (td.fSelected == 1) {
      fLeftMat->MasterToLocal(point, local);
      fLeftMat->MasterToLocalVect(dir, ldir);
      fLeft->ComputeNormal(local,ldir,lnorm);
      fLeftMat->LocalToMasterVect(lnorm, norm);
      return;
   }
   if (td.fSelected == 2) {
      fRightMat->MasterToLocal(point, local);
      fRightMat->MasterToLocalVect(dir, ldir);
      fRight->ComputeNormal(local,ldir,lnorm);
      fRightMat->LocalToMasterVect(lnorm, norm);
      return;
   }            
   fLeftMat->MasterToLocal(point, local);
   if (fLeft->Contains(local)) {
      fLeftMat->MasterToLocalVect(dir, ldir);
      fLeft->ComputeNormal(local,ldir,lnorm);
      fLeftMat->LocalToMasterVect(lnorm, norm);
      return;
   }   
   fRightMat->MasterToLocal(point, local);
   if (fRight->Contains(local)) {
      fRightMat->MasterToLocalVect(dir, ldir);
      fRight->ComputeNormal(local,ldir,lnorm);
      fRightMat->LocalToMasterVect(lnorm, norm);
      return;
   }   
   // Propagate forward/backward to see which of the components is intersected first
   local[0] = point[0] + 1E-5*dir[0];
   local[1] = point[1] + 1E-5*dir[1];
   local[2] = point[2] + 1E-5*dir[2];

   if (!Contains(local)) {
      local[0] = point[0] - 1E-5*dir[0];
      local[1] = point[1] - 1E-5*dir[1];
      local[2] = point[2] - 1E-5*dir[2];
      if (!Contains(local)) return;
   }
   ComputeNormal(local,dir,norm);   
}

//______________________________________________________________________________
Int_t TGeoUnion::DistanceToPrimitive(Int_t /*px*/, Int_t /*py*/)
{
// Compute minimum distance to shape vertices.
   return 9999;
}

//______________________________________________________________________________
Double_t TGeoUnion::DistFromInside(const Double_t *point, const Double_t *dir, Int_t iact,
                              Double_t step, Double_t *safe) const
{
// Computes distance from a given point inside the shape to its boundary.
   if (iact<3 && safe) {
      // compute safe distance
      *safe = Safety(point,kTRUE);
      if (iact==0) return TGeoShape::Big();
      if (iact==1 && step<*safe) return TGeoShape::Big();
   }

   Double_t local[3], local1[3], master[3], ldir[3], rdir[3], pushed[3];
   memcpy(master, point, 3*sizeof(Double_t));
   Int_t i;
   TGeoBoolNode *node = (TGeoBoolNode*)this;
   Double_t d1=0., d2=0., snxt=0., eps=0.;
   fLeftMat->MasterToLocalVect(dir, ldir);
   fRightMat->MasterToLocalVect(dir, rdir);
   fLeftMat->MasterToLocal(point, local);
   Bool_t inside1 = fLeft->Contains(local);
   if (inside1) d1 = fLeft->DistFromInside(local, ldir, 3);
   else memcpy(local1, local, 3*sizeof(Double_t));
   fRightMat->MasterToLocal(point, local);
   Bool_t inside2 = fRight->Contains(local);
   if (inside2) d2 = fRight->DistFromInside(local, rdir, 3);
   if (!(inside1 | inside2)) {
   // This is a pathological case when the point is on the boundary
      d1 = fLeft->DistFromOutside(local1, ldir, 3);
      if (d1<1.E-3) {
         eps = d1+TGeoShape::Tolerance();
         for (i=0; i<3; i++) local1[i] += eps*ldir[i];
         inside1 = kTRUE;
         d1 = fLeft->DistFromInside(local1, ldir, 3);
         d1 += eps;
      } else {      
         d2 = fRight->DistFromOutside(local, rdir, 3);
         if (d2<1.E-3) {
           eps = d2+TGeoShape::Tolerance();
           for (i=0; i<3; i++) local[i] += eps*rdir[i];
           inside2 = kTRUE;
           d2 = fRight->DistFromInside(local, rdir, 3);
           d2 += eps;
        }
     }      
   }
   while (inside1 || inside2) {
      if (inside1 && inside2) {
         if (d1<d2) {      
            snxt += d1;
            node->SetSelected(1);
            // propagate to exit of left shape
            inside1 = kFALSE;
            for (i=0; i<3; i++) master[i] += d1*dir[i];
            // check if propagated point is in right shape        
            fRightMat->MasterToLocal(master, local);
            inside2 = fRight->Contains(local);
            if (!inside2) return snxt;
            d2 = fRight->DistFromInside(local, rdir, 3);
            if (d2 < TGeoShape::Tolerance()) return snxt;
         } else {
            snxt += d2;
            node->SetSelected(2);
            // propagate to exit of right shape
            inside2 = kFALSE;
            for (i=0; i<3; i++) master[i] += d2*dir[i];
            // check if propagated point is in left shape        
            fLeftMat->MasterToLocal(master, local);
            inside1 = fLeft->Contains(local);
            if (!inside1) return snxt;
            d1 = fLeft->DistFromInside(local, ldir, 3);
            if (d1 < TGeoShape::Tolerance()) return snxt;
         }
      } 
      if (inside1) {
         snxt += d1;
         node->SetSelected(1);
         // propagate to exit of left shape
         inside1 = kFALSE;
         for (i=0; i<3; i++) {
            master[i] += d1*dir[i];
            pushed[i] = master[i]+(1.+d1)*TGeoShape::Tolerance()*dir[i];
         }   
         // check if propagated point is in right shape        
         fRightMat->MasterToLocal(pushed, local);
         inside2 = fRight->Contains(local);
         if (!inside2) return snxt;
         d2 = fRight->DistFromInside(local, rdir, 3);
         if (d2 < TGeoShape::Tolerance()) return snxt;
         d2 += (1.+d1)*TGeoShape::Tolerance();
      }   
      if (inside2) {
         snxt += d2;
         node->SetSelected(2);
         // propagate to exit of right shape
         inside2 = kFALSE;
         for (i=0; i<3; i++) {
            master[i] += d2*dir[i];
            pushed[i] = master[i]+(1.+d2)*TGeoShape::Tolerance()*dir[i];
         }   
         // check if propagated point is in left shape        
         fLeftMat->MasterToLocal(pushed, local);
         inside1 = fLeft->Contains(local);
         if (!inside1) return snxt;
         d1 = fLeft->DistFromInside(local, ldir, 3);
         if (d1 < TGeoShape::Tolerance()) return snxt;
         d1 += (1.+d2)*TGeoShape::Tolerance();
      }
   }      
   return snxt;
}

//______________________________________________________________________________
Double_t TGeoUnion::DistFromOutside(const Double_t *point, const Double_t *dir, Int_t iact,
                              Double_t step, Double_t *safe) const
{
// Compute distance from a given outside point to the shape.
   if (iact<3 && safe) {
      // compute safe distance
      *safe = Safety(point,kFALSE);
      if (iact==0) return TGeoShape::Big();
      if (iact==1 && step<*safe) return TGeoShape::Big();
   }
   TGeoBoolNode *node = (TGeoBoolNode*)this;
   Double_t local[3], ldir[3], rdir[3];
   Double_t d1, d2, snxt;
   fLeftMat->MasterToLocal(point, &local[0]);
   fLeftMat->MasterToLocalVect(dir, &ldir[0]);
   fRightMat->MasterToLocalVect(dir, &rdir[0]);
   d1 = fLeft->DistFromOutside(&local[0], &ldir[0], iact, step, safe);
   fRightMat->MasterToLocal(point, &local[0]);
   d2 = fRight->DistFromOutside(&local[0], &rdir[0], iact, step, safe);
   if (d1<d2) {
      snxt = d1;
      node->SetSelected(1);
   } else {
      snxt = d2;
      node->SetSelected(2);
   }      
   return snxt;
}

//______________________________________________________________________________
Int_t TGeoUnion::GetNpoints()
{
// Returns number of vertices for the composite shape described by this union.
   Int_t itot=0;
   Double_t point[3];
   Double_t tolerance = TGeoShape::Tolerance();
   if (fNpoints) return fNpoints;
   // Local points for the left shape
   Int_t nleft = fLeft->GetNmeshVertices();
   Double_t *points1 = new Double_t[3*nleft];
   fLeft->SetPoints(points1);
   // Local points for the right shape
   Int_t nright = fRight->GetNmeshVertices();
   Double_t *points2 = new Double_t[3*nright];
   fRight->SetPoints(points2);
   Double_t *points = new Double_t[3*(nleft+nright)];
   for (Int_t i=0; i<nleft; i++) {
      if (TMath::Abs(points1[3*i])<tolerance && TMath::Abs(points1[3*i+1])<tolerance) continue;
      fLeftMat->LocalToMaster(&points1[3*i], &points[3*itot]);
      fRightMat->MasterToLocal(&points[3*itot], point);
      if (!fRight->Contains(point)) itot++;
   }
   for (Int_t i=0; i<nright; i++) {
      if (TMath::Abs(points2[3*i])<tolerance && TMath::Abs(points2[3*i+1])<tolerance) continue;
      fRightMat->LocalToMaster(&points2[3*i], &points[3*itot]);
      fLeftMat->MasterToLocal(&points[3*itot], point);
      if (!fLeft->Contains(point)) itot++;
   }
   fNpoints = itot;
   fPoints = new Double_t[3*fNpoints];
   memcpy(fPoints, points, 3*fNpoints*sizeof(Double_t));
   delete [] points1;
   delete [] points2;
   delete [] points;
   return fNpoints;         
}

//______________________________________________________________________________
Double_t TGeoUnion::Safety(const Double_t *point, Bool_t in) const
{
// Compute safety distance for a union node;
   Double_t local1[3], local2[3];
   fLeftMat->MasterToLocal(point,local1);
   Bool_t in1 = fLeft->Contains(local1);
   fRightMat->MasterToLocal(point,local2);
   Bool_t in2 = fRight->Contains(local2);
   Bool_t intrue = in1 | in2;
   if (intrue^in) return 0.0;
   Double_t saf1 = fLeft->Safety(local1, in1);
   Double_t saf2 = fRight->Safety(local2, in2);
   if (in1 && in2) return TMath::Min(saf1, saf2);
   if (in1)        return saf1;
   if (in2)        return saf2;
   return TMath::Min(saf1,saf2);
}   

//_____________________________________________________________________________
void TGeoUnion::SavePrimitive(std::ostream &out, Option_t *option /*= ""*/)
{
// Save a primitive as a C++ statement(s) on output stream "out".
   TGeoBoolNode::SavePrimitive(out,option);
   out << "   pBoolNode = new TGeoUnion(";
   out << fLeft->GetPointerName() << ",";
   out << fRight->GetPointerName() << ",";
   if (!fLeftMat->IsIdentity()) out << fLeftMat->GetPointerName() << ",";
   else                         out << "0,";
   if (!fRightMat->IsIdentity()) out << fRightMat->GetPointerName() << ");" << std::endl;
   else                         out << "0);" << std::endl;
}   

//______________________________________________________________________________
void TGeoUnion::Sizeof3D() const
{
// Register 3D size of this shape.
   TGeoBoolNode::Sizeof3D();
}
   

ClassImp(TGeoSubtraction)

//______________________________________________________________________________
TGeoBoolNode *TGeoSubtraction::MakeClone() const
{
// Make a clone of this. Pointers are preserved.
   return new TGeoSubtraction(fLeft, fRight, fLeftMat, fRightMat);
}

//______________________________________________________________________________
void TGeoSubtraction::Paint(Option_t *option)
{
// Paint method.
   TVirtualViewer3D *viewer = gPad->GetViewer3D();

   if (!viewer) {
      Error("Paint", "gPad->GetViewer3D() returned 0, cannot work with composite!\n");
      return;
   }

   viewer->AddCompositeOp(TBuffer3D::kCSDifference);

   TGeoBoolNode::Paint(option);
}

//______________________________________________________________________________
TGeoSubtraction::TGeoSubtraction()
{
// Default constructor
}

//______________________________________________________________________________
TGeoSubtraction::TGeoSubtraction(const char *expr1, const char *expr2)
          :TGeoBoolNode(expr1, expr2)
{
// Constructor
}

//______________________________________________________________________________
TGeoSubtraction::TGeoSubtraction(TGeoShape *left, TGeoShape *right, TGeoMatrix *lmat, TGeoMatrix *rmat)
                :TGeoBoolNode(left,right,lmat,rmat)
{
// Constructor providing pointers to components
   if (left->TestShapeBit(TGeoShape::kGeoHalfSpace)) {
      Fatal("TGeoSubstraction", "Substractions from a half-space (%s) not allowed", left->GetName());
   }
}

//______________________________________________________________________________
TGeoSubtraction::~TGeoSubtraction()
{
// Destructor
// --- deletion of components handled by TGeoManager class.
}

//______________________________________________________________________________
void TGeoSubtraction::ComputeBBox(Double_t &dx, Double_t &dy, Double_t &dz, Double_t *origin)
{
// Compute bounding box corresponding to a subtraction of two shapes.
   TGeoBBox *box = (TGeoBBox*)fLeft;
   if (box->IsNullBox()) fLeft->ComputeBBox();
   Double_t vert[24];
   Double_t pt[3];
   Int_t i;
   Double_t xmin, xmax, ymin, ymax, zmin, zmax;
   xmin = ymin = zmin = TGeoShape::Big();
   xmax = ymax = zmax = -TGeoShape::Big();
   box->SetBoxPoints(&vert[0]);
   for (i=0; i<8; i++) {
      fLeftMat->LocalToMaster(&vert[3*i], &pt[0]);
      if (pt[0]<xmin) xmin=pt[0];
      if (pt[0]>xmax) xmax=pt[0];
      if (pt[1]<ymin) ymin=pt[1];
      if (pt[1]>ymax) ymax=pt[1];
      if (pt[2]<zmin) zmin=pt[2];
      if (pt[2]>zmax) zmax=pt[2];
   }   
   dx = 0.5*(xmax-xmin);
   origin[0] = 0.5*(xmin+xmax);
   dy = 0.5*(ymax-ymin);
   origin[1] = 0.5*(ymin+ymax);
   dz = 0.5*(zmax-zmin);
   origin[2] = 0.5*(zmin+zmax);
}   

//_____________________________________________________________________________
void TGeoSubtraction::ComputeNormal(const Double_t *point, const Double_t *dir, Double_t *norm)
{
// Normal computation in POINT. The orientation is chosen so that DIR.dot.NORM>0.
   ThreadData_t& td = GetThreadData();
   norm[0] = norm[1] = 0.;
   norm[2] = 1.;
   Double_t local[3], ldir[3], lnorm[3];
   if (td.fSelected == 1) {
      fLeftMat->MasterToLocal(point, local);
      fLeftMat->MasterToLocalVect(dir, ldir);
      fLeft->ComputeNormal(local,ldir,lnorm);
      fLeftMat->LocalToMasterVect(lnorm, norm);
      return;
   }
   if (td.fSelected == 2) {
      fRightMat->MasterToLocal(point, local);
      fRightMat->MasterToLocalVect(dir, ldir);
      fRight->ComputeNormal(local,ldir,lnorm);
      fRightMat->LocalToMasterVect(lnorm, norm);
      return;
   }
   fRightMat->MasterToLocal(point,local);
   if (fRight->Contains(local)) {
      fRightMat->MasterToLocalVect(dir,ldir);
      fRight->ComputeNormal(local,ldir, lnorm);
      fRightMat->LocalToMasterVect(lnorm,norm);
      return;
   }   
   fLeftMat->MasterToLocal(point,local);
   if (!fLeft->Contains(local)) {
      fLeftMat->MasterToLocalVect(dir,ldir);
      fLeft->ComputeNormal(local,ldir, lnorm);
      fLeftMat->LocalToMasterVect(lnorm,norm);
      return;
   }
   // point is inside left shape, but not inside the right
   local[0] = point[0]+1E-5*dir[0];
   local[1] = point[1]+1E-5*dir[1];
   local[2] = point[2]+1E-5*dir[2];
   if (Contains(local)) {
      local[0] = point[0]-1E-5*dir[0];
      local[1] = point[1]-1E-5*dir[1];
      local[2] = point[2]-1E-5*dir[2];
      if (Contains(local)) return;
   }  
   ComputeNormal(local,dir,norm);
}

//______________________________________________________________________________
Bool_t TGeoSubtraction::Contains(const Double_t *point) const
{
// Find if a subtraction of two shapes contains a given point
   Double_t local[3];
   fLeftMat->MasterToLocal(point, &local[0]);
   Bool_t inside = fLeft->Contains(&local[0]);
   if (!inside) return kFALSE;
   fRightMat->MasterToLocal(point, &local[0]);
   inside = !fRight->Contains(&local[0]);
   return inside;
}

//______________________________________________________________________________
Int_t TGeoSubtraction::DistanceToPrimitive(Int_t /*px*/, Int_t /*py*/)
{
// Compute minimum distance to shape vertices
   return 9999;
}

//______________________________________________________________________________
Double_t TGeoSubtraction::DistFromInside(const Double_t *point, const Double_t *dir, Int_t iact,
                              Double_t step, Double_t *safe) const
{
// Compute distance from a given point inside to the shape boundary.
   if (iact<3 && safe) {
      // compute safe distance
      *safe = Safety(point,kTRUE);
      if (iact==0) return TGeoShape::Big();
      if (iact==1 && step<*safe) return TGeoShape::Big();
   }
   TGeoBoolNode *node = (TGeoBoolNode*)this;
   Double_t local[3], ldir[3], rdir[3];
   Double_t d1, d2, snxt=0.;
   fLeftMat->MasterToLocal(point, &local[0]);
   fLeftMat->MasterToLocalVect(dir, &ldir[0]);
   fRightMat->MasterToLocalVect(dir, &rdir[0]);
   d1 = fLeft->DistFromInside(&local[0], &ldir[0], iact, step, safe);
   fRightMat->MasterToLocal(point, &local[0]);
   d2 = fRight->DistFromOutside(&local[0], &rdir[0], iact, step, safe);
   if (d1<d2) {
      snxt = d1;
      node->SetSelected(1);
   } else {
      snxt = d2;
      node->SetSelected(2);
   }      
   return snxt;
}   

//______________________________________________________________________________
Double_t TGeoSubtraction::DistFromOutside(const Double_t *point, const Double_t *dir, Int_t iact,
                              Double_t step, Double_t *safe) const
{
// Compute distance from a given point outside to the shape.
   if (iact<3 && safe) {
      // compute safe distance
      *safe = Safety(point,kFALSE);
      if (iact==0) return TGeoShape::Big();
      if (iact==1 && step<*safe) return TGeoShape::Big();
   }
   TGeoBoolNode *node = (TGeoBoolNode*)this;
   Double_t local[3], master[3], ldir[3], rdir[3];
   memcpy(&master[0], point, 3*sizeof(Double_t));
   Int_t i;
   Double_t d1, d2, snxt=0.;
   fRightMat->MasterToLocal(point, &local[0]);
   fLeftMat->MasterToLocalVect(dir, &ldir[0]);
   fRightMat->MasterToLocalVect(dir, &rdir[0]);
   // check if inside '-'
   Bool_t inside = fRight->Contains(&local[0]);
   Double_t epsil = 0.;
   while (1) {
      if (inside) {
         // propagate to outside of '-'
         node->SetSelected(2);
         d1 = fRight->DistFromInside(&local[0], &rdir[0], iact, step, safe);
         snxt += d1+epsil;
         for (i=0; i<3; i++) master[i] += (d1+1E-8)*dir[i];
         epsil = 1.E-8;
         // now master outside '-'; check if inside '+'
         fLeftMat->MasterToLocal(&master[0], &local[0]);
         if (fLeft->Contains(&local[0])) return snxt;
      } 
      // master outside '-' and outside '+' ;  find distances to both
      node->SetSelected(1);
      fLeftMat->MasterToLocal(&master[0], &local[0]);
      d2 = fLeft->DistFromOutside(&local[0], &ldir[0], iact, step, safe);
      if (d2>1E20) return TGeoShape::Big();
      
      fRightMat->MasterToLocal(&master[0], &local[0]);
      d1 = fRight->DistFromOutside(&local[0], &rdir[0], iact, step, safe);
      if (d2<d1-TGeoShape::Tolerance()) {
         snxt += d2+epsil;
         return snxt;
      }   
      // propagate to '-'
      snxt += d1+epsil;
      for (i=0; i<3; i++) master[i] += (d1+1E-8)*dir[i];
      epsil = 1.E-8;
      // now inside '-' and not inside '+'
      fRightMat->MasterToLocal(&master[0], &local[0]);
      inside = kTRUE;
   }
}

//______________________________________________________________________________
Int_t TGeoSubtraction::GetNpoints()
{
// Returns number of vertices for the composite shape described by this subtraction.
   Int_t itot=0;
   Double_t point[3];
   Double_t tolerance = TGeoShape::Tolerance();
   if (fNpoints) return fNpoints;
   Int_t nleft = fLeft->GetNmeshVertices();
   Int_t nright = fRight->GetNmeshVertices();
   Double_t *points = new Double_t[3*(nleft+nright)];
   Double_t *points1 = new Double_t[3*nleft];
   fLeft->SetPoints(points1);
   for (Int_t i=0; i<nleft; i++) {
      if (TMath::Abs(points1[3*i])<tolerance && TMath::Abs(points1[3*i+1])<tolerance) continue;
      fLeftMat->LocalToMaster(&points1[3*i], &points[3*itot]);
      fRightMat->MasterToLocal(&points[3*itot], point);
      if (!fRight->Contains(point)) itot++;
   }
   Double_t *points2 = new Double_t[3*nright];
   fRight->SetPoints(points2);
   for (Int_t i=0; i<nright; i++) {
      if (TMath::Abs(points2[3*i])<tolerance && TMath::Abs(points2[3*i+1])<tolerance) continue;
      fRightMat->LocalToMaster(&points2[3*i], &points[3*itot]);
      fLeftMat->MasterToLocal(&points[3*itot], point);
      if (fLeft->Contains(point)) itot++;
   }
   fNpoints = itot;
   fPoints = new Double_t[3*fNpoints];
   memcpy(fPoints, points, 3*fNpoints*sizeof(Double_t));
   delete [] points1;
   delete [] points2;
   delete [] points;
   return fNpoints;         
}

//______________________________________________________________________________
Double_t TGeoSubtraction::Safety(const Double_t *point, Bool_t in) const
{
// Compute safety distance for a union node;
   Double_t local1[3], local2[3];
   fLeftMat->MasterToLocal(point,local1);
   Bool_t in1 = fLeft->Contains(local1);
   fRightMat->MasterToLocal(point,local2);
   Bool_t in2 = fRight->Contains(local2);
   Bool_t intrue = in1 && (!in2);
   if (in^intrue) return 0.0;
   Double_t saf1 = fLeft->Safety(local1, in1);
   Double_t saf2 = fRight->Safety(local2, in2);
   if (in1 && in2) return saf2;
   if (in1)        return TMath::Min(saf1,saf2);
   if (in2)        return TMath::Max(saf1,saf2);
   return saf1;
}   

//_____________________________________________________________________________
void TGeoSubtraction::SavePrimitive(std::ostream &out, Option_t *option /*= ""*/)
{
// Save a primitive as a C++ statement(s) on output stream "out".
   TGeoBoolNode::SavePrimitive(out,option);
   out << "   pBoolNode = new TGeoSubtraction(";
   out << fLeft->GetPointerName() << ",";
   out << fRight->GetPointerName() << ",";
   if (!fLeftMat->IsIdentity()) out << fLeftMat->GetPointerName() << ",";
   else                         out << "0,";
   if (!fRightMat->IsIdentity()) out << fRightMat->GetPointerName() << ");" << std::endl;
   else                         out << "0);" << std::endl;
}   

//______________________________________________________________________________
void TGeoSubtraction::Sizeof3D() const
{
// Register 3D size of this shape.
   TGeoBoolNode::Sizeof3D();
}

ClassImp(TGeoIntersection)

//______________________________________________________________________________
TGeoBoolNode *TGeoIntersection::MakeClone() const
{
// Make a clone of this. Pointers are preserved.
   return new TGeoIntersection(fLeft, fRight, fLeftMat, fRightMat);
}

//______________________________________________________________________________
void TGeoIntersection::Paint(Option_t *option)
{
// Paint method.
   TVirtualViewer3D *viewer = gPad->GetViewer3D();

   if (!viewer) {
      Error("Paint", "gPad->GetViewer3D() returned 0, cannot work with composite!\n");
      return;
   }

   viewer->AddCompositeOp(TBuffer3D::kCSIntersection);

   TGeoBoolNode::Paint(option);
}

//______________________________________________________________________________
TGeoIntersection::TGeoIntersection()
{
// Default constructor
}

//______________________________________________________________________________
TGeoIntersection::TGeoIntersection(const char *expr1, const char *expr2)
          :TGeoBoolNode(expr1, expr2)
{
// Constructor
}

//______________________________________________________________________________
TGeoIntersection::TGeoIntersection(TGeoShape *left, TGeoShape *right, TGeoMatrix *lmat, TGeoMatrix *rmat)
                 :TGeoBoolNode(left,right,lmat,rmat)
{
// Constructor providing pointers to components
   Bool_t hs1 = (fLeft->TestShapeBit(TGeoShape::kGeoHalfSpace))?kTRUE:kFALSE;
   Bool_t hs2 = (fRight->TestShapeBit(TGeoShape::kGeoHalfSpace))?kTRUE:kFALSE;
   if (hs1 && hs2) Fatal("ctor", "cannot intersect two half-spaces: %s * %s", left->GetName(), right->GetName());
}

//______________________________________________________________________________
TGeoIntersection::~TGeoIntersection()
{
// Destructor
// --- deletion of components handled by TGeoManager class.
}

//______________________________________________________________________________
void TGeoIntersection::ComputeBBox(Double_t &dx, Double_t &dy, Double_t &dz, Double_t *origin)
{
// Compute bounding box corresponding to a intersection of two shapes.
   Bool_t hs1 = (fLeft->TestShapeBit(TGeoShape::kGeoHalfSpace))?kTRUE:kFALSE;
   Bool_t hs2 = (fRight->TestShapeBit(TGeoShape::kGeoHalfSpace))?kTRUE:kFALSE;
   Double_t vert[48];
   Double_t pt[3];
   Int_t i;
   Double_t xmin1, xmax1, ymin1, ymax1, zmin1, zmax1;
   Double_t xmin2, xmax2, ymin2, ymax2, zmin2, zmax2;
   xmin1 = ymin1 = zmin1 = xmin2 = ymin2 = zmin2 = TGeoShape::Big();
   xmax1 = ymax1 = zmax1 = xmax2 = ymax2 = zmax2 =  -TGeoShape::Big();
   if (!hs1) {
      if (((TGeoBBox*)fLeft)->IsNullBox()) fLeft->ComputeBBox();
      ((TGeoBBox*)fLeft)->SetBoxPoints(&vert[0]);
      for (i=0; i<8; i++) {
         fLeftMat->LocalToMaster(&vert[3*i], &pt[0]);
         if (pt[0]<xmin1) xmin1=pt[0];
         if (pt[0]>xmax1) xmax1=pt[0];
         if (pt[1]<ymin1) ymin1=pt[1];
         if (pt[1]>ymax1) ymax1=pt[1];
         if (pt[2]<zmin1) zmin1=pt[2];
         if (pt[2]>zmax1) zmax1=pt[2];
      }   
   }   
   if (!hs2) {
      if (((TGeoBBox*)fRight)->IsNullBox()) fRight->ComputeBBox();
      ((TGeoBBox*)fRight)->SetBoxPoints(&vert[24]);
      for (i=8; i<16; i++) {
         fRightMat->LocalToMaster(&vert[3*i], &pt[0]);
         if (pt[0]<xmin2) xmin2=pt[0];
         if (pt[0]>xmax2) xmax2=pt[0];
         if (pt[1]<ymin2) ymin2=pt[1];
         if (pt[1]>ymax2) ymax2=pt[1];
         if (pt[2]<zmin2) zmin2=pt[2];
         if (pt[2]>zmax2) zmax2=pt[2];
      }
   }      
   if (hs1) {
      dx = 0.5*(xmax2-xmin2);
      origin[0] = 0.5*(xmax2+xmin2);   
      dy = 0.5*(ymax2-ymin2);
      origin[1] = 0.5*(ymax2+ymin2);   
      dz = 0.5*(zmax2-zmin2);
      origin[2] = 0.5*(zmax2+zmin2);   
      return;
   }            
   if (hs2) {
      dx = 0.5*(xmax1-xmin1);
      origin[0] = 0.5*(xmax1+xmin1);   
      dy = 0.5*(ymax1-ymin1);
      origin[1] = 0.5*(ymax1+ymin1);   
      dz = 0.5*(zmax1-zmin1);
      origin[2] = 0.5*(zmax1+zmin1);   
      return;
   }   
   Double_t sort[4];
   Int_t isort[4];
   sort[0] = xmin1;
   sort[1] = xmax1;
   sort[2] = xmin2;
   sort[3] = xmax2;
   TMath::Sort(4, &sort[0], &isort[0], kFALSE);
   if (isort[1]%2) {
      Warning("ComputeBBox", "shapes %s and %s do not intersect", fLeft->GetName(), fRight->GetName());
      dx = dy = dz = 0;
      memset(origin, 0, 3*sizeof(Double_t));
      return;
   }
   dx = 0.5*(sort[isort[2]]-sort[isort[1]]);
   origin[0] = 0.5*(sort[isort[1]]+sort[isort[2]]);   
   sort[0] = ymin1;
   sort[1] = ymax1;
   sort[2] = ymin2;
   sort[3] = ymax2;
   TMath::Sort(4, &sort[0], &isort[0], kFALSE);
   if (isort[1]%2) {
      Warning("ComputeBBox", "shapes %s and %s do not intersect", fLeft->GetName(), fRight->GetName());
      dx = dy = dz = 0;
      memset(origin, 0, 3*sizeof(Double_t));
      return;
   }
   dy = 0.5*(sort[isort[2]]-sort[isort[1]]);
   origin[1] = 0.5*(sort[isort[1]]+sort[isort[2]]);   
   sort[0] = zmin1;
   sort[1] = zmax1;
   sort[2] = zmin2;
   sort[3] = zmax2;
   TMath::Sort(4, &sort[0], &isort[0], kFALSE);
   if (isort[1]%2) {
      Warning("ComputeBBox", "shapes %s and %s do not intersect", fLeft->GetName(), fRight->GetName());
      dx = dy = dz = 0;
      memset(origin, 0, 3*sizeof(Double_t));
      return;
   }
   dz = 0.5*(sort[isort[2]]-sort[isort[1]]);
   origin[2] = 0.5*(sort[isort[1]]+sort[isort[2]]);   
}   

//_____________________________________________________________________________
void TGeoIntersection::ComputeNormal(const Double_t *point, const Double_t *dir, Double_t *norm)
{
// Normal computation in POINT. The orientation is chosen so that DIR.dot.NORM>0.
   ThreadData_t& td = GetThreadData();
   Double_t local[3], ldir[3], lnorm[3];
   norm[0] = norm[1] = 0.;
   norm[2] = 1.;
   if (td.fSelected == 1) {
      fLeftMat->MasterToLocal(point, local);
      fLeftMat->MasterToLocalVect(dir, ldir);
      fLeft->ComputeNormal(local,ldir,lnorm);
      fLeftMat->LocalToMasterVect(lnorm, norm);
      return;
   }
   if (td.fSelected == 2) {
      fRightMat->MasterToLocal(point, local);
      fRightMat->MasterToLocalVect(dir, ldir);
      fRight->ComputeNormal(local,ldir,lnorm);
      fRightMat->LocalToMasterVect(lnorm, norm);
      return;
   }            
   fLeftMat->MasterToLocal(point,local);
   if (!fLeft->Contains(local)) {
      fLeftMat->MasterToLocalVect(dir,ldir);
      fLeft->ComputeNormal(local,ldir,lnorm);
      fLeftMat->LocalToMasterVect(lnorm,norm);
      return;
   }
   fRightMat->MasterToLocal(point,local);
   if (!fRight->Contains(local)) {
      fRightMat->MasterToLocalVect(dir,ldir);
      fRight->ComputeNormal(local,ldir,lnorm);
      fRightMat->LocalToMasterVect(lnorm,norm);
      return;
   }
   // point is inside intersection.
   local[0] = point[0] + 1E-5*dir[0];   
   local[1] = point[1] + 1E-5*dir[1];   
   local[2] = point[2] + 1E-5*dir[2];
   if (Contains(local)) {
      local[0] = point[0] - 1E-5*dir[0];   
      local[1] = point[1] - 1E-5*dir[1];   
      local[2] = point[2] - 1E-5*dir[2];
      if (Contains(local)) return;
   }
   ComputeNormal(local,dir,norm);   
}

//______________________________________________________________________________
Bool_t TGeoIntersection::Contains(const Double_t *point) const
{
// Find if a intersection of two shapes contains a given point
   Double_t local[3];
   fLeftMat->MasterToLocal(point, &local[0]);
   Bool_t inside = fLeft->Contains(&local[0]);
   if (!inside) return kFALSE;
   fRightMat->MasterToLocal(point, &local[0]);
   inside = fRight->Contains(&local[0]);
   return inside;
}

//______________________________________________________________________________
Int_t TGeoIntersection::DistanceToPrimitive(Int_t /*px*/, Int_t /*py*/)
{
// Compute minimum distance to shape vertices
   return 9999;
}

//______________________________________________________________________________
Double_t TGeoIntersection::DistFromInside(const Double_t *point, const Double_t *dir, Int_t iact,
                              Double_t step, Double_t *safe) const
{
// Compute distance from a given point inside to the shape boundary.
   if (iact<3 && safe) {
      // compute safe distance
      *safe = Safety(point,kTRUE);
      if (iact==0) return TGeoShape::Big();
      if (iact==1 && step<*safe) return TGeoShape::Big();
   }
   TGeoBoolNode *node = (TGeoBoolNode*)this;
   Double_t local[3], ldir[3], rdir[3];
   Double_t d1, d2, snxt=0.;
   fLeftMat->MasterToLocal(point, &local[0]);
   fLeftMat->MasterToLocalVect(dir, &ldir[0]);
   fRightMat->MasterToLocalVect(dir, &rdir[0]);
   d1 = fLeft->DistFromInside(&local[0], &ldir[0], iact, step, safe);
   fRightMat->MasterToLocal(point, &local[0]);
   d2 = fRight->DistFromInside(&local[0], &rdir[0], iact, step, safe);
   if (d1<d2) {
      snxt = d1;
      node->SetSelected(1);
   } else {
      snxt = d2;
      node->SetSelected(2);
   }      
   return snxt;
}   

//______________________________________________________________________________
Double_t TGeoIntersection::DistFromOutside(const Double_t *point, const Double_t *dir, Int_t iact,
                              Double_t step, Double_t *safe) const
{
// Compute distance from a given point outside to the shape.
   Double_t tol = TGeoShape::Tolerance();
   if (iact<3 && safe) {
      // compute safe distance
      *safe = Safety(point,kFALSE);
      if (iact==0) return TGeoShape::Big();
      if (iact==1 && step<*safe) return TGeoShape::Big();
   }
   TGeoBoolNode *node = (TGeoBoolNode*)this;
   Double_t lpt[3], rpt[3], master[3], ldir[3], rdir[3];
   memcpy(master, point, 3*sizeof(Double_t));
   Int_t i;
   Double_t d1 = 0.;
   Double_t d2 = 0.;
   fLeftMat->MasterToLocal(point, lpt);
   fRightMat->MasterToLocal(point, rpt);
   fLeftMat->MasterToLocalVect(dir, ldir);
   fRightMat->MasterToLocalVect(dir, rdir);
   Bool_t inleft = fLeft->Contains(lpt);
   Bool_t inright = fRight->Contains(rpt);
   node->SetSelected(0);
   Double_t snext = 0.0;
   if (inleft && inright) {
      // It is vey likely to have a numerical issue and the point should
      // be logically outside one of the shapes
      d1 = fLeft->DistFromInside(lpt,ldir,3);
      d2 = fRight->DistFromInside(rpt,rdir,3);
      if (d1<1.E-3) inleft = kFALSE;
      if (d2<1.E-3) inright = kFALSE;
      if (inleft && inright) return snext;
   }   

   while (1) {
      d1 = d2 = 0;
      if (!inleft)  {
         d1 = fLeft->DistFromOutside(lpt,ldir,3);
         d1 = TMath::Max(d1,tol);
         if (d1>1E20) return TGeoShape::Big();
      }
      if (!inright) {  
         d2 = fRight->DistFromOutside(rpt,rdir,3);
         d2 = TMath::Max(d2,tol);
         if (d2>1E20) return TGeoShape::Big();
      }
   
      if (d1>d2) {
         // propagate to left shape
         snext += d1;
         node->SetSelected(1);
         inleft = kTRUE;
         for (i=0; i<3; i++) master[i] += d1*dir[i];
         fRightMat->MasterToLocal(master,rpt);
         // Push rpt to avoid a bad boundary condition
         for (i=0; i<3; i++) rpt[i] += tol*rdir[i];
         // check if propagated point is inside right shape
         inright = fRight->Contains(rpt);
         if (inright) return snext;
         // here inleft=true, inright=false         
      } else {
         // propagate to right shape
         snext += d2;
         node->SetSelected(2);
         inright = kTRUE;
         for (i=0; i<3; i++) master[i] += d2*dir[i];
         fLeftMat->MasterToLocal(master,lpt);
         // Push lpt to avoid a bad boundary condition
         for (i=0; i<3; i++) lpt[i] += tol*ldir[i];
         // check if propagated point is inside left shape
         inleft = fLeft->Contains(lpt);
         if (inleft) return snext;
         // here inleft=false, inright=true
      }            
   }   
   return snext;
}      

//______________________________________________________________________________
Int_t TGeoIntersection::GetNpoints()
{
// Returns number of vertices for the composite shape described by this intersection.
   Int_t itot=0;
   Double_t point[3];
   Double_t tolerance = TGeoShape::Tolerance();
   if (fNpoints) return fNpoints;
   Int_t nleft = fLeft->GetNmeshVertices();
   Int_t nright = fRight->GetNmeshVertices();
   Double_t *points = new Double_t[3*(nleft+nright)];
   Double_t *points1 = new Double_t[3*nleft];
   fLeft->SetPoints(points1);
   for (Int_t i=0; i<nleft; i++) {
      if (TMath::Abs(points1[3*i])<tolerance && TMath::Abs(points1[3*i+1])<tolerance) continue;
      fLeftMat->LocalToMaster(&points1[3*i], &points[3*itot]);
      fRightMat->MasterToLocal(&points[3*itot], point);
      if (fRight->Contains(point)) itot++;
   }
   Double_t *points2 = new Double_t[3*nright];
   fRight->SetPoints(points2);
   for (Int_t i=0; i<nright; i++) {
      if (TMath::Abs(points2[3*i])<tolerance && TMath::Abs(points2[3*i+1])<tolerance) continue;
      fRightMat->LocalToMaster(&points2[3*i], &points[3*itot]);
      fLeftMat->MasterToLocal(&points[3*itot], point);
      if (fLeft->Contains(point)) itot++;
   }
   fNpoints = itot;
   fPoints = new Double_t[3*fNpoints];
   memcpy(fPoints, points, 3*fNpoints*sizeof(Double_t));
   delete [] points1;
   delete [] points2;
   delete [] points;
   return fNpoints;         
}

//______________________________________________________________________________
Double_t TGeoIntersection::Safety(const Double_t *point, Bool_t in) const
{
// Compute safety distance for a union node;
   Double_t local1[3], local2[3];
   fLeftMat->MasterToLocal(point,local1);
   Bool_t in1 = fLeft->Contains(local1);
   fRightMat->MasterToLocal(point,local2);
   Bool_t in2 = fRight->Contains(local2);
   Bool_t intrue = in1 & in2;
   if (in^intrue) return 0.0;
   Double_t saf1 = fLeft->Safety(local1, in1);
   Double_t saf2 = fRight->Safety(local2, in2);
   if (in1 && in2) return TMath::Min(saf1, saf2);
   if (in1)        return saf2;
   if (in2)        return saf1;
   return TMath::Max(saf1,saf2);
}   

//_____________________________________________________________________________
void TGeoIntersection::SavePrimitive(std::ostream &out, Option_t *option /*= ""*/)
{
// Save a primitive as a C++ statement(s) on output stream "out".
   TGeoBoolNode::SavePrimitive(out,option);
   out << "   pBoolNode = new TGeoIntersection(";
   out << fLeft->GetPointerName() << ",";
   out << fRight->GetPointerName() << ",";
   if (!fLeftMat->IsIdentity()) out << fLeftMat->GetPointerName() << ",";
   else                         out << "0,";
   if (!fRightMat->IsIdentity()) out << fRightMat->GetPointerName() << ");" << std::endl;
   else                         out << "0);" << std::endl;
}   

//______________________________________________________________________________
void TGeoIntersection::Sizeof3D() const
{
// Register 3D size of this shape.
   TGeoBoolNode::Sizeof3D();
}
