TGeoCompositeShape.cxx

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// @(#)root/geom:$Id$
// Author: Andrei Gheata   31/01/02

/*************************************************************************
 * 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.             *
 *************************************************************************/

/** \class TGeoCompositeShape
\ingroup Geometry_classes

Class handling Boolean composition of shapes

  Composite shapes are Boolean combination of two or more shape
components. The supported boolean operations are union (+), intersection (*)
and subtraction. Composite shapes derive from the base TGeoShape class,
therefore providing all shape features : computation of bounding box, finding
if a given point is inside or outside the combination, as well as computing the
distance to entering/exiting. It can be directly used for creating volumes or
used in the definition of other composite shapes.

  Composite shapes are provided in order to complement and extend the set of
basic shape primitives. They have a binary tree internal structure, therefore
all shape-related geometry queries are signals propagated from top level down
to the final leaves, while the provided answers are assembled and interpreted
back at top. This CSG hierarchy is effective for small number of components,
while performance drops dramatically for large structures. Building a complete
geometry in this style is virtually possible but highly not recommended.

### Structure of composite shapes

  A composite shape can always be regarded as the result of a Boolean operation
between only two shape components. All information identifying these two
components as well as their positions with respect to the frame of the composite
is represented by an object called Boolean node. A composite shape just have
a pointer to such a Boolean node. Since the shape components may also be
composites, they will also contain binary Boolean nodes branching other two
shapes in the hierarchy. Any such branch ends-up when the final leaves are no
longer composite shapes, but basic primitives.

\image html geom_booltree.png

  Suppose that A, B, C and D represent basic shapes, we will illustrate
how the internal representation of few combinations look like. We do this
only for the sake of understanding how to create them in a proper way, since
the user interface for this purpose is in fact very simple. We will ignore
for the time being the positioning of components. The definition of a composite
shape takes an expression where the identifiers are shape names. The
expression is parsed and decomposed in 2 sub-expressions and the top-level
Boolean operator.

#### A+B+C

  This represent the union of A, B and C. Both union operators are at the
same level. Since:

~~~ {.cpp}
       A+B+C = (A+B)+C = A+(B+C)
~~~

the first (+) is taken as separator, hence the expression split:

~~~ {.cpp}
       A and B+C
~~~

A Boolean node of type TGeoUnion("A", "B+C") is created. This tries to replace
the 2 expressions by actual pointers to corresponding shapes.
The first expression (A) contains no operators therefore is interpreted as
representing a shape. The shape named "A" is searched into the list of shapes
handled by the manager class and stored as the "left" shape in the Boolean
union node. Since the second expression is not yet fully decomposed, the "right"
shape in the combination is created as a new composite shape. This will split
at its turn B+C into B and C and create a TGeoUnion("B","C"). The B and C
identifiers will be looked for and replaced by the pointers to the actual shapes
into the new node. Finally, the composite "A+B+C" will be represented as:

~~~ {.cpp}
                A
               |
  [A+B+C] = (+)             B
               |           |
                [B+C] = (+)
                           |
                            C
~~~

where [] is a composite shape, (+) is a Boolean node of type union and A, B,
C are pointers to the corresponding shapes.
  Building this composite shapes takes the following line :

~~~ {.cpp}
     TGeoCompositeShape *cs1 = new TGeoCompositeShape("CS1", "A+B+C");
~~~

#### (A+B)-(C+D)
  This expression means: subtract the union of C and D from the union of A and
B. The usage of parenthesis to force operator precedence is always recommended.
The representation of the corresponding composite shape looks like:

~~~ {.cpp}
                                  A
                                 |
                      [A+B] = (+)
                     |           |
  [(A+B)-(C+D)] = (-)           C B
                     |         |
                      [C+D]=(+)
                               |
                                D
~~~

~~~ {.cpp}
     TGeoCompositeShape *cs2 = new TGeoCompositeShape("CS2", "(A+B)-(C+D)");
~~~

  Building composite shapes as in the 2 examples above is not always quite
useful since we were using un-positioned shapes. When supplying just shape
names as identifiers, the created boolean nodes will assume that the shapes
are positioned with an identity transformation with respect to the frame of
the created composite. In order to provide some positioning of the combination
components, we have to attach after each shape identifier the name of an
existing transformation, separated by a colon. Obviously all transformations
created for this purpose have to be objects with unique names in order to be
properly substituted during parsing.
  Let's look at the code implementing the second example :

~~~ {.cpp}
     TGeoTranslation *t1 = new TGeoTranslation("t1",0,0,-20);
     TGeoTranslation *t2 = new TGeoTranslation("t2",0,0, 20);
     TGeoRotation *r1 = new TGeoRotation("r1"); // transformations need names
     r1->SetAngles(90,30,90,120,0,0); // rotation with 30 degrees about Z
     TGeoTube *a = new TGeoTube(0, 10,20);
     a->SetName("A");                 // shapes need names too
     TGeoTube *b = new TGeoTube(0, 20,20);
     b->SetName("B");
     TGeoBBox *c = new TGeoBBox(10,10,50);
     c->SetName("C");
     TGeoBBox *d = new TGeoBBox(50,10,10);
     d->SetName("D");

     TGeoCompositeShape *cs;
     cs = new TGeoCompositeShape("CS", "(A:t1+B:t2)-(C+D:r1)");
~~~

  The newly created composite looks like 2 cylinders of different radii sitting
one on top of the other and having 2 rectangular holes : a longitudinal one
along Z axis corresponding to C and an other one in the XY plane due to D.
  One should have in mind that the same shape or matrix identifier can be
used many times in the same expression. For instance:

~~~ {.cpp}
     (A:t1-A:t2)*B:t1
~~~

is a valid expression. Expressions that cannot be parsed or identifiers that
cannot be substituted by existing objects generate error messages.
  Composite shapes can be subsequently used for defining volumes. Moreover,
these volumes may have daughters but these have to obey overlapping/extruding
rules (see TGeoVolume). Volumes created based on composite shapes cannot be
divided. Visualization of such volumes is currently not implemented.
*/

#include "Riostream.h"
#include "TRandom3.h"

#include "TGeoManager.h"
#include "TGeoMatrix.h"
#include "TGeoBoolNode.h"
#include "TVirtualGeoPainter.h"

#include "TVirtualPad.h"
#include "TVirtualViewer3D.h"
#include "TBuffer3D.h"
#include "TBuffer3DTypes.h"

#include "TGeoCompositeShape.h"
ClassImp(TGeoCompositeShape)

////////////////////////////////////////////////////////////////////////////////
/// Needed just for cleanup.

void TGeoCompositeShape::ClearThreadData() const
{
   if (fNode) fNode->ClearThreadData();
}

////////////////////////////////////////////////////////////////////////////////
/// Needed just for cleanup.

void TGeoCompositeShape::CreateThreadData(Int_t nthreads)
{
   if (fNode) fNode->CreateThreadData(nthreads);
}

////////////////////////////////////////////////////////////////////////////////
/// Default constructor

TGeoCompositeShape::TGeoCompositeShape()
                   :TGeoBBox(0, 0, 0)
{
   SetShapeBit(TGeoShape::kGeoComb);
   fNode  = 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Default constructor

TGeoCompositeShape::TGeoCompositeShape(const char *name, const char *expression)
                   :TGeoBBox(0, 0, 0)
{
   SetShapeBit(TGeoShape::kGeoComb);
   SetName(name);
   fNode  = 0;
   MakeNode(expression);
   if (!fNode) {
      Error("ctor", "Composite %s: cannot parse expression: %s", name, expression);
      return;
   }
   ComputeBBox();
}

////////////////////////////////////////////////////////////////////////////////
/// Default constructor

TGeoCompositeShape::TGeoCompositeShape(const char *expression)
                   :TGeoBBox(0, 0, 0)
{
   SetShapeBit(TGeoShape::kGeoComb);
   fNode  = 0;
   MakeNode(expression);
   if (!fNode) {
      TString message = TString::Format("Composite (no name) could not parse expression %s", expression);
      Error("ctor", "%s", message.Data());
      return;
   }
   ComputeBBox();
}

////////////////////////////////////////////////////////////////////////////////
/// Constructor with a Boolean node

TGeoCompositeShape::TGeoCompositeShape(const char *name, TGeoBoolNode *node)
                   :TGeoBBox(0,0,0)
{
   SetName(name);
   fNode = node;
   if (!fNode) {
      Error("ctor", "Composite shape %s has null node", name);
      return;
   }
   ComputeBBox();
}

////////////////////////////////////////////////////////////////////////////////
/// destructor

TGeoCompositeShape::~TGeoCompositeShape()
{
   if (fNode) delete fNode;
}

////////////////////////////////////////////////////////////////////////////////
/// Computes capacity of this shape [length^3] by sampling with 1% error.

Double_t TGeoCompositeShape::Capacity() const
{
   Double_t pt[3];
   if (!gRandom) gRandom = new TRandom3();
   Double_t vbox = 8*fDX*fDY*fDZ; // cm3
   Int_t igen=0;
   Int_t iin = 0;
   while (iin<10000) {
      pt[0] = fOrigin[0]-fDX+2*fDX*gRandom->Rndm();
      pt[1] = fOrigin[1]-fDY+2*fDY*gRandom->Rndm();
      pt[2] = fOrigin[2]-fDZ+2*fDZ*gRandom->Rndm();
      igen++;
      if (Contains(pt)) iin++;
   }
   Double_t capacity = iin*vbox/igen;
   return capacity;
}

////////////////////////////////////////////////////////////////////////////////
/// compute bounding box of the sphere

void TGeoCompositeShape::ComputeBBox()
{
   if(fNode) fNode->ComputeBBox(fDX, fDY, fDZ, fOrigin);
}

////////////////////////////////////////////////////////////////////////////////
/// Computes normal vector in POINT to the composite shape.

void TGeoCompositeShape::ComputeNormal(const Double_t *point, const Double_t *dir, Double_t *norm)
{
   if (fNode) fNode->ComputeNormal(point,dir,norm);
}

////////////////////////////////////////////////////////////////////////////////
/// Tests if point is inside the shape.

Bool_t TGeoCompositeShape::Contains(const Double_t *point) const
{
   if (fNode) return fNode->Contains(point);
   return kFALSE;
}

////////////////////////////////////////////////////////////////////////////////
/// Compute closest distance from point px,py to each corner.

Int_t TGeoCompositeShape::DistancetoPrimitive(Int_t px, Int_t py)
{
   const Int_t numPoints = GetNmeshVertices();
   return ShapeDistancetoPrimitive(numPoints, px, py);
}

////////////////////////////////////////////////////////////////////////////////
/// Compute distance from outside point to this composite shape.
/// Check if the bounding box is crossed within the requested distance

Double_t TGeoCompositeShape::DistFromOutside(const Double_t *point, const Double_t *dir, Int_t iact,
                                      Double_t step, Double_t *safe) const
{
   Double_t sdist = TGeoBBox::DistFromOutside(point,dir, fDX, fDY, fDZ, fOrigin, step);
   if (sdist>=step) return TGeoShape::Big();
   if (fNode) return fNode->DistFromOutside(point, dir, iact, step, safe);
   return TGeoShape::Big();
}

////////////////////////////////////////////////////////////////////////////////
/// Compute distance from inside point to outside of this composite shape.

Double_t TGeoCompositeShape::DistFromInside(const Double_t *point, const Double_t *dir, Int_t iact,
                                      Double_t step, Double_t *safe) const
{
   if (fNode) return fNode->DistFromInside(point, dir, iact, step, safe);
   return TGeoShape::Big();
}

////////////////////////////////////////////////////////////////////////////////
/// Divide all range of iaxis in range/step cells

TGeoVolume *TGeoCompositeShape::Divide(TGeoVolume  * /*voldiv*/, const char * /*divname*/, Int_t /*iaxis*/,
                                       Int_t /*ndiv*/, Double_t /*start*/, Double_t /*step*/)
{
   Error("Divide", "Composite shapes cannot be divided");
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Returns numbers of vertices, segments and polygons composing the shape mesh.

void TGeoCompositeShape::GetMeshNumbers(Int_t &nvert, Int_t &nsegs, Int_t &npols) const
{
   nvert = GetNmeshVertices();
   nsegs = 0;
   npols = 0;
}

////////////////////////////////////////////////////////////////////////////////
/// print shape parameters

void TGeoCompositeShape::InspectShape() const
{
   printf("*** TGeoCompositeShape : %s = %s\n", GetName(), GetTitle());
   printf(" Bounding box:\n");
   TGeoBBox::InspectShape();
}

////////////////////////////////////////////////////////////////////////////////
/// Make a boolean node according to the top level boolean operation of expression.
/// Propagates signal to branches until expression is fully decomposed.
///   printf("Making node for : %s\n", expression);

void TGeoCompositeShape::MakeNode(const char *expression)
{
   if (fNode) delete fNode;
   fNode = 0;
   SetTitle(expression);
   TString sleft, sright, smat;
   Int_t boolop;
   boolop = TGeoManager::Parse(expression, sleft, sright, smat);
   if (boolop<0) {
      // fail
      Error("MakeNode", "parser error");
      return;
   }
   if (smat.Length())
      Warning("MakeNode", "no geometrical transformation allowed at this level");
   switch (boolop) {
      case 0:
         Error("MakeNode", "Expression has no boolean operation");
         return;
      case 1:
         fNode = new TGeoUnion(sleft.Data(), sright.Data());
         return;
      case 2:
         fNode = new TGeoSubtraction(sleft.Data(), sright.Data());
         return;
      case 3:
         fNode = new TGeoIntersection(sleft.Data(), sright.Data());
   }
}

////////////////////////////////////////////////////////////////////////////////
/// Paint this composite shape into the current 3D viewer
/// Returns bool flag indicating if the caller should continue to
/// paint child objects

Bool_t TGeoCompositeShape::PaintComposite(Option_t *option) const
{
   Bool_t addChildren = kTRUE;

   TVirtualGeoPainter *painter = gGeoManager->GetGeomPainter();
   TVirtualViewer3D * viewer = gPad->GetViewer3D();
   if (!painter || !viewer) return kFALSE;

   if (fNode) {
      // Fill out the buffer for the composite shape - nothing extra
      // over TGeoBBox
      Bool_t preferLocal = viewer->PreferLocalFrame();
      if (TBuffer3D::GetCSLevel()) preferLocal = kFALSE;
      static TBuffer3D buffer(TBuffer3DTypes::kComposite);
      FillBuffer3D(buffer, TBuffer3D::kCore|TBuffer3D::kBoundingBox,
                   preferLocal);

      Bool_t paintComponents = kTRUE;

      // Start a composite shape, identified by this buffer
      if (!TBuffer3D::GetCSLevel())
         paintComponents = viewer->OpenComposite(buffer, &addChildren);

      TBuffer3D::IncCSLevel();

      // Paint the boolean node - will add more buffers to viewer
      TGeoHMatrix *matrix = (TGeoHMatrix*)TGeoShape::GetTransform();
      TGeoHMatrix backup(*matrix);
      if (preferLocal) matrix->Clear();
      if (paintComponents) fNode->Paint(option);
      if (preferLocal) *matrix = backup;
      // Close the composite shape
      if (!TBuffer3D::DecCSLevel())
         viewer->CloseComposite();
   }

   return addChildren;
}

////////////////////////////////////////////////////////////////////////////////
/// Register the shape and all components to TGeoManager class.

void TGeoCompositeShape::RegisterYourself()
{
   if (gGeoManager->GetListOfShapes()->FindObject(this)) return;
   gGeoManager->AddShape(this);
   TGeoMatrix *matrix;
   TGeoShape  *shape;
   TGeoCompositeShape *comp;
   if (fNode) {
      matrix = fNode->GetLeftMatrix();
      if (!matrix->IsRegistered()) matrix->RegisterYourself();
      else if (!gGeoManager->GetListOfMatrices()->FindObject(matrix)) {
         gGeoManager->GetListOfMatrices()->Add(matrix);
      }
      matrix = fNode->GetRightMatrix();
      if (!matrix->IsRegistered()) matrix->RegisterYourself();
      else if (!gGeoManager->GetListOfMatrices()->FindObject(matrix)) {
         gGeoManager->GetListOfMatrices()->Add(matrix);
      }
      shape = fNode->GetLeftShape();
      if (!gGeoManager->GetListOfShapes()->FindObject(shape)) {
         if (shape->IsComposite()) {
            comp = (TGeoCompositeShape*)shape;
            comp->RegisterYourself();
         } else {
            gGeoManager->AddShape(shape);
         }
      }
      shape = fNode->GetRightShape();
      if (!gGeoManager->GetListOfShapes()->FindObject(shape)) {
         if (shape->IsComposite()) {
            comp = (TGeoCompositeShape*)shape;
            comp->RegisterYourself();
         } else {
            gGeoManager->AddShape(shape);
         }
      }
   }
}

////////////////////////////////////////////////////////////////////////////////
/// computes the closest distance from given point to this shape, according
/// to option. The matching point on the shape is stored in spoint.

Double_t TGeoCompositeShape::Safety(const Double_t *point, Bool_t in) const
{
   if (fNode) return fNode->Safety(point,in);
   return 0.;
}

////////////////////////////////////////////////////////////////////////////////
/// Save a primitive as a C++ statement(s) on output stream "out".

void TGeoCompositeShape::SavePrimitive(std::ostream &out, Option_t *option /*= ""*/)
{
   if (TObject::TestBit(kGeoSavePrimitive)) return;
   if (fNode) fNode->SavePrimitive(out,option);
   out << "   // Shape: " << GetName() << " type: " << ClassName() << std::endl;
   out << "   TGeoShape *" << GetPointerName() << " = new TGeoCompositeShape(\"" << GetName() << "\", pBoolNode);" << std::endl;
   if (strlen(GetTitle())) out << "   " << GetPointerName() << "->SetTitle(\"" << GetTitle() << "\");" << std::endl;
   TObject::SetBit(TGeoShape::kGeoSavePrimitive);
}

////////////////////////////////////////////////////////////////////////////////
/// create points for a composite shape

void TGeoCompositeShape::SetPoints(Double_t *points) const
{
   if (fNode) fNode->SetPoints(points);
}

////////////////////////////////////////////////////////////////////////////////
/// create points for a composite shape

void TGeoCompositeShape::SetPoints(Float_t *points) const
{
   if (fNode) fNode->SetPoints(points);
}

////////////////////////////////////////////////////////////////////////////////
/// compute size of this 3D object

void TGeoCompositeShape::Sizeof3D() const
{
   if (fNode) fNode->Sizeof3D();
}

////////////////////////////////////////////////////////////////////////////////
/// Return number of vertices of the mesh representation

Int_t TGeoCompositeShape::GetNmeshVertices() const
{
   if (!fNode) return 0;
   return fNode->GetNpoints();
}

////////////////////////////////////////////////////////////////////////////////
/// Check the inside status for each of the points in the array.
/// Input: Array of point coordinates + vector size
/// Output: Array of Booleans for the inside of each point

void TGeoCompositeShape::Contains_v(const Double_t *points, Bool_t *inside, Int_t vecsize) const
{
   for (Int_t i=0; i<vecsize; i++) inside[i] = Contains(&points[3*i]);
}

////////////////////////////////////////////////////////////////////////////////
/// Compute the normal for an array o points so that norm.dot.dir is positive
/// Input: Arrays of point coordinates and directions + vector size
/// Output: Array of normal directions

void TGeoCompositeShape::ComputeNormal_v(const Double_t *points, const Double_t *dirs, Double_t *norms, Int_t vecsize)
{
   for (Int_t i=0; i<vecsize; i++) ComputeNormal(&points[3*i], &dirs[3*i], &norms[3*i]);
}

////////////////////////////////////////////////////////////////////////////////
/// Compute distance from array of input points having directions specified by dirs. Store output in dists

void TGeoCompositeShape::DistFromInside_v(const Double_t *points, const Double_t *dirs, Double_t *dists, Int_t vecsize, Double_t* step) const
{
   for (Int_t i=0; i<vecsize; i++) dists[i] = DistFromInside(&points[3*i], &dirs[3*i], 3, step[i]);
}

////////////////////////////////////////////////////////////////////////////////
/// Compute distance from array of input points having directions specified by dirs. Store output in dists

void TGeoCompositeShape::DistFromOutside_v(const Double_t *points, const Double_t *dirs, Double_t *dists, Int_t vecsize, Double_t* step) const
{
   for (Int_t i=0; i<vecsize; i++) dists[i] = DistFromOutside(&points[3*i], &dirs[3*i], 3, step[i]);
}

////////////////////////////////////////////////////////////////////////////////
/// Compute safe distance from each of the points in the input array.
/// Input: Array of point coordinates, array of statuses for these points, size of the arrays
/// Output: Safety values

void TGeoCompositeShape::Safety_v(const Double_t *points, const Bool_t *inside, Double_t *safe, Int_t vecsize) const
{
   for (Int_t i=0; i<vecsize; i++) safe[i] = Safety(&points[3*i], inside[i]);
}