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// $Id: G4VCSGface.hh 67011 2013-01-29 16:17:41Z gcosmo $
//
//
// --------------------------------------------------------------------
// GEANT 4 class header file
//
//
// G4VCSGface
//
// Class description:
//
// Definition of the virtual base class G4VCSGface, one side (or face)
// of a CSG-like solid. It should be possible to build a CSG entirely out of
// connecting CSG faces.
//
// Each face has an inside and outside surface, the former represents
// the inside of the volume, the latter, the outside.
//
// Virtual members:
//
// -------------------------------------------------------------------
// Intersect( const G4ThreeVector &p, const G4ThreeVector &v,
// G4bool outGoing, G4double surfTolerance,
// G4double &distance, G4double &distFromSurface,
// G4ThreeVector &normal, G4bool &allBehind );
//
// p - (in) position
// v - (in) direction (assumed to be a unit vector)
// outgoing - (in) true, to consider only inside surfaces
// false, to consider only outside surfaces
// distance - (out) distance to intersection
// distFromSurface - (out) distance from surface (along surface normal),
// < 0 if the point is in front of the surface
// normal - (out) normal of surface at intersection point
// allBehind - (out) true, if entire surface is behind normal
//
// return value = true if there is an intersection,
// false if there is no intersection
// (all output arguments undefined)
//
// Determine the distance along a line to the face.
//
// -------------------------------------------------------------------
// Distance( const G4ThreeVector &p, const G4bool outgoing );
//
// p - (in) position
// outgoing - (in) true, to consider only inside surfaces
// false, to consider only outside surfaces
//
// return value = distance to closest surface satisifying requirements
// or kInfinity if no such surface exists
//
// Determine the distance of a point from either the inside or outside
// surfaces of the face.
//
// -------------------------------------------------------------------
// Inside( const G4ThreeVector &p, const G4double tolerance,
// G4double *bestDistance );
//
// p - (in) position
// tolerance - (in) tolerance defining the bounds of the "kSurface",
// nominally equal to kCarTolerance/2
// bestDistance - (out) distance to closest surface (in or out)
//
// return value = kInside if the point is closest to the inside surface
// kOutside if the point is closest to the outside surface
// kSurface if the point is withing tolerance of the surface
//
// Determine whether a point is inside, outside, or on the surface of
// the face.
//
// -------------------------------------------------------------------
// Normal( const G4ThreeVector &p, G4double *bestDistance );
//
// p - (in) position
// bestDistance - (out) distance to closest surface (in or out)
//
// return value = the normal of the surface nearest the point
//
// Return normal of surface closest to the point.
//
// -------------------------------------------------------------------
// Extent( const G4ThreeVector axis );
//
// axis - (in) unit vector defining direction
//
// return value = the largest point along the given axis of the
// the face's extent.
//
// -------------------------------------------------------------------
// CalculateExtent( const EAxis pAxis,
// const G4VoxelLimit &pVoxelLimit,
// const G4AffineTransform &pTransform,
// G4double &min, G4double &max )
//
// pAxis - (in) The x,y, or z axis in which to check
// the shapes 3D extent against
// pVoxelLimit - (in) Limits along x, y, and/or z axes
// pTransform - (in) A coordinate transformation on which
// to apply to the shape before testing
// min - (out) If the face has any point on its
// surface after tranformation and limits
// along pAxis that is smaller than the value
// of min, than it is used to replace min.
// Undefined if the return value is false.
// max - (out) Same as min, except for the largest
// point.
// Undefined if the return value is false.
//
// return value = true if anything remains of the face
//
// Calculate the extent of the face for the voxel navigator.
// In analogy with CalculateExtent for G4VCSGfaceted, this is
// done in the following steps:
//
// 1. Transform the face using pTranform, an arbitrary 3D
// rotation/offset/reflection
// 2. Clip the face to those boundaries as specified in
// pVoxelLimit. This may include limits in any number
// of x, y, or z axes.
// 3. For each part of the face that remains (there could
// be many separate pieces in general):
// 4. Check to see if the piece overlaps the currently
// existing limits along axis pAxis. For
// pVoxelLimit.IsLimited(pAxis) = false, there are
// no limits.
// 5. For a piece that does overlap, update min/max
// accordingly (within confines of pre-existing
// limits) along the direction pAxis.
// 6. If min/max were updated, return true
//
// -------------------------------------------------------------------
// G3VCSGface *Clone()
//
// This method is invoked by G4CSGfaceted during the copy constructor
// or the assignment operator. Its purpose is to return a pointer
// (of type G4VCSGface) to a duplicate copy of the face.
// The implementation is straight forward for inherited classes. Example:
//
// G4VCSGface G4PolySideFace::Clone() { return new G4PolySideFace(*this); }
//
// Of course, this assumes the copy constructor of G4PolySideFace is
// correctly implemented.
//
// Implementation notes:
// * distance.
// The meaning of distance includes the boundaries of the face.
// For example, for a rectangular, planer face:
//
// A | B | C
// | |
// -------+--------------+-----
// D | I | E
// | |
// -------+--------------+-----
// F | G | H
// | |
//
// A, C, F, and H: closest distance is the distance to
// the adjacent corner.
//
// B, D, E, and G: closest distance is the distance to
// the adjacent line.
//
// I: normal distance to plane
//
// For non-planer faces, one can use the normal to decide when
// a point falls off the edge and then act accordingly.
//
//
// Usage:
//
// A CSG shape can be defined by putting together any number of generic
// faces, as long as the faces cover the entire surface of the shape
// without overlapping.
//
// G4VSolid::CalculateExtent
//
// Define unit vectors along the specified transform axis.
// Use the inverse of the specified coordinate transformation to rotate
// these unit vectors. Loop over each face, call face->Extent, and save
// the maximum value.
//
// G4VSolid::Inside
//
// To decide if a point is inside, outside, or on the surface of the shape,
// loop through all faces, and find the answer from face->Inside which gives
// a value of "bestDistance" smaller than any other. While looping, if any
// face->Inside returns kSurface, this value can be returned immediately.
//
// EInside answer;
// G4VCSGface *face = faces;
// G4double best = kInfinity;
// do {
// G4double distance;
// EInside result = (*face)->Inside( p, kCarTolerance/2, distance );
// if (result == kSurface) return kSurface;
// if (distance < best) {
// best = distance;
// answer = result;
// }
// } while( ++face < faces + numFaces );
//
// return(answer);
//
// G4VSolid::SurfaceNormal
//
// Loop over all faces, call face->Normal, and return the normal to the face
// that is closest to the point.
//
// G4VSolid::DistanceToIn(p)
//
// Loop over all faces, invoking face->Distance with outgoing = false,
// and save the answer that is smallest.
//
// G4VSolid::DistanceToIn(p,v)
//
// Loop over all faces, invoking face->Intersect with outgoing = false,
// and save the answer that is smallest.
//
// G4VSolid::DistanceToOut(p)
//
// Loop over all faces, invoking face->Distance with outgoing = true,
// and save the answer that is smallest.
//
// G4VSolid::DistanceToOut(p,v)
//
// Loop over all faces, invoking face->Intersect with outgoing = true,
// and save the answer that is smallest. If there is more than one answer,
// or if allBehind is false for the one answer, return validNorm as false.
// Author:
// David C. Williams (davidw@scipp.ucsc.edu)
// --------------------------------------------------------------------
#ifndef G4VCSGface_hh
#define G4VCSGface_hh
#include "G4Types.hh"
#include "G4ThreeVector.hh"
#include "geomdefs.hh"
#include "G4VSolid.hh"
class G4VoxelLimits;
class G4AffineTransform;
class G4SolidExtentList;
class G4VCSGface
{
public: // with description
G4VCSGface() {}
virtual ~G4VCSGface() {}
virtual G4bool Intersect( const G4ThreeVector &p, const G4ThreeVector &v,
G4bool outgoing, G4double surfTolerance,
G4double &distance, G4double &distFromSurface,
G4ThreeVector &normal, G4bool &allBehind ) = 0;
virtual G4double Distance( const G4ThreeVector &p, G4bool outgoing ) = 0;
virtual EInside Inside( const G4ThreeVector &p, G4double tolerance,
G4double *bestDistance ) = 0;
virtual G4ThreeVector Normal( const G4ThreeVector &p,
G4double *bestDistance ) = 0;
virtual G4double Extent( const G4ThreeVector axis ) = 0;
virtual void CalculateExtent( const EAxis axis,
const G4VoxelLimits &voxelLimit,
const G4AffineTransform &tranform,
G4SolidExtentList &extentList ) = 0;
virtual G4VCSGface* Clone() = 0;
virtual G4double SurfaceArea( ) = 0;
virtual G4ThreeVector GetPointOnFace() = 0;
};
#endif