library: libGeom #include "TGeoNode.h"

# TGeoNodeMatrix

class description - source file - inheritance tree (.pdf)

## class TGeoNodeMatrix : public TGeoNode

| Inheritance Chart:
`TObject`
| <- | `TNamed`
`TGeoAtt`
| <- | `TGeoNode`
| <- | `TGeoNodeMatrix` |

        public:

                              TGeoNodeMatrix()
                              TGeoNodeMatrix(const TGeoVolume* vol, const TGeoMatrix* matrix)
                              TGeoNodeMatrix(const TGeoNodeMatrix&)
                      virtual ~TGeoNodeMatrix()
               static TClass* Class()
                virtual Int_t GetByteCount() const
          virtual TGeoMatrix* GetMatrix() const
                virtual Int_t GetOptimalVoxels() const
              virtual TClass* IsA() const
               virtual Bool_t IsFolder() const
            virtual TGeoNode* MakeCopyNode() const
              TGeoNodeMatrix& operator=(const TGeoNodeMatrix&)
                         void SetMatrix(const TGeoMatrix* matrix)
                 virtual void ShowMembers(TMemberInspector& insp, char* parent)
                 virtual void Streamer(TBuffer& b)
                         void StreamerNVirtual(TBuffer& b)

### Data Members

        private:

          TGeoMatrix* fMatrix  transf. matrix of fNode in fMother system

## Class Description

     TGeoNode
    _________
       A node represent a volume positioned inside another.They store links to both
     volumes and to the TGeoMatrix representing the relative positioning. Node are
     never instanciated directly by users, but created as a result of volume operations.
     Adding a volume named A with a given user ID inside a volume B will create a node
     node named A_ID. This will be added to the list of nodes stored by B. Also,
     when applying a division operation in N slices to a volume A, a list of nodes
     B_1, B_2, ..., B_N is also created. A node B_i does not represent a unique
     object in the geometry because its container A might be at its turn positioned
     as node inside several other volumes. Only when a complete branch of nodes
     is fully defined up to the top node in the geometry, a given path like:
           /TOP_1/.../A_3/B_7 will represent an unique object. Its global transformation
     matrix can be computed as the pile-up of all local transformations in its
     branch. We will therefore call "logical graph" the hierarchy defined by nodes
     and volumes. The expansion of the logical graph by all possible paths defines
     a tree sructure where all nodes are unique "touchable" objects. We will call
     this the "physical tree". Unlike the logical graph, the physical tree can
     become a huge structure with several milions of nodes in case of complex
     geometries, therefore it is not always a good idea to keep it transient
     in memory. Since a the logical and physical structures are correlated, the
     modeller rather keeps track only of the current branch, updating the current
     global matrix at each change of the level in geometry. The current physical node
     is not an object that can be asked for at a given moment, but rather represented
     by the combination: current node + current global matrix. However, physical nodes
     have unique ID's that can be retreived for a given modeler state. These can be
     fed back to the modeler in order to force a physical node to become current.
     The advantage of this comes from the fact that all navigation queries check
     first the current node, therefore knowing the location of a point in the
     geometry can be saved as a starting state for later use.

       Nodes can be declared as "overlapping" in case they do overlap with other
     nodes inside the same container or extrude this container. Non-overlapping
     nodes can be created with:

          TGeoVolume::AddNode(TGeoVolume *daughter, Int_t copy_No, TGeoMatrix *matr);

     The creation of overapping nodes can be done with a similar prototype:

          TGeoVolume::AddNodeOverlap(same arguments);

     When closing the geometry, overlapping nodes perform a check of possible
     overlaps with their neighbours. These are stored and checked all the time
     during navigation, therefore navigation is slower when embedding such nodes
     into geometry.

       Node have visualization attributes as volume have. When undefined by users,
     painting a node on a pad will take the corresponding volume attributes.

/* */

TGeoNodeMatrix()

     Default constructor

TGeoNodeMatrix(const TGeoVolume *vol, const TGeoMatrix *matrix) : TGeoNode(vol)

     Constructor.

~TGeoNodeMatrix()

     Destructor

Int_t GetByteCount() const

     return the total size in bytes of this node

Int_t GetOptimalVoxels() const

    --- Returns type of optimal voxelization for this node.
     type = 0 -> cartesian
     type = 1 -> cylindrical

TGeoNode* MakeCopyNode() const

     make a copy of this node
       printf("      Making a copy of node %s\n", GetName());

### Inline Functions

                     Bool_t IsFolder() const
                TGeoMatrix* GetMatrix() const
                       void SetMatrix(const TGeoMatrix* matrix)
                    TClass* Class()
                    TClass* IsA() const
                       void ShowMembers(TMemberInspector& insp, char* parent)
                       void Streamer(TBuffer& b)
                       void StreamerNVirtual(TBuffer& b)
             TGeoNodeMatrix TGeoNodeMatrix(const TGeoNodeMatrix&)
            TGeoNodeMatrix& operator=(const TGeoNodeMatrix&)

Author: Andrei Gheata 24/10/01
Last update: root/geom:$Name: $:$Id: TGeoNode.cxx,v 1.24 2005/04/01 13:53:17 brun Exp $
Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *