TPoints3DABC.cxx

Go to the documentation of this file.

// @(#)root/g3d:$Id$
// Author: Valery Fine(fine@mail.cern.ch)   04/05/99

/*************************************************************************
 * 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 "TPoints3DABC.h"
#include "TMath.h"

ClassImp(TPoints3DABC);

/** \class TPoints3DABC
\ingroup g3d
Abstract class to define Arrays of 3D points.
*/

////////////////////////////////////////////////////////////////////////////////
/// Add one 3D point defined by x,y,z to the array of the points
/// as its last element

Int_t TPoints3DABC::Add(Float_t x, Float_t y, Float_t z)
{
   return AddLast(x,y,z);
}

////////////////////////////////////////////////////////////////////////////////
/// Add one 3D point defined by x,y,z to the array of the points
/// as its last element

Int_t TPoints3DABC::AddLast(Float_t x, Float_t y, Float_t z)
{
   return SetNextPoint(x,y,z);
}

////////////////////////////////////////////////////////////////////////////////
/// Compute distance from point px,py to an axis of the band defined.
///  by pair points  (x1,y1),(x2,y2) where lineWidth is the width of the band
///
///  Compute the closest distance of approach from point px,py to this line.
///  The distance is computed in pixels units.
///
///  Algorithm:
/// ~~~ {.cpp}
///
///    A(x1,y1)         P                             B(x2,y2)
///    ------------------------------------------------
///                     I
///                     I
///                     I
///                     I
///                    M(x,y)
///
///  Let us call  a = distance AM     a2=a**2
///               b = distance BM     b2=b**2
///               c = distance AB     c2=c**2
///               d = distance PM     d2=d**2
///               u = distance AP     u2=u**2
///               v = distance BP     v2=v**2     c = u + v
///
///  d2 = a2 - u2
///  d2 = b2 - v2  = b2 -(c-u)**2
///     ==> u = (a2 -b2 +c2)/2c
///
///   Float_t x1    = gPad->XtoAbsPixel(xp1);
///   Float_t y1    = gPad->YtoAbsPixel(yp1);
///   Float_t x2    = gPad->XtoAbsPixel(xp2);
///   Float_t y2    = gPad->YtoAbsPixel(yp2);
/// ~~~

Int_t TPoints3DABC::DistancetoLine(Int_t px, Int_t py, Float_t x1, Float_t y1, Float_t x2, Float_t y2, Int_t lineWidth )
{
   Float_t xl, xt, yl, yt;
   Float_t x     = px;
   Float_t y     = py;
   if (x1 < x2) {xl = x1; xt = x2;}
   else         {xl = x2; xt = x1;}
   if (y1 < y2) {yl = y1; yt = y2;}
   else         {yl = y2; yt = y1;}
   if (x < xl-2 || x> xt+2) return 9999;  //following algorithm only valid in the box
   if (y < yl-2 || y> yt+2) return 9999;  //surrounding the line
   Float_t xx1   = x  - x1;
   Float_t xx2   = x  - x2;
   Float_t x1x2  = x1 - x2;
   Float_t yy1   = y  - y1;
   Float_t yy2   = y  - y2;
   Float_t y1y2  = y1 - y2;
   Float_t a2    = xx1*xx1   + yy1*yy1;
   Float_t b2    = xx2*xx2   + yy2*yy2;
   Float_t c2    = x1x2*x1x2 + y1y2*y1y2;
   if (c2 <= 0)  return 9999;
   Float_t c     = TMath::Sqrt(c2);
   Float_t u     = (a2 - b2 + c2)/(2*c);
   Float_t d2    = TMath::Abs(a2 - u*u);
   if (d2 < 0)   return 9999;

   return Int_t(TMath::Sqrt(d2) - 0.5*float(lineWidth));
}

////////////////////////////////////////////////////////////////////////////////
/// Add one 3D point defined by x,y,z to the array of the points
/// as its last element

Int_t TPoints3DABC::SetNextPoint(Float_t x, Float_t y, Float_t z)
{
   return SetPoint(GetLastPosition()+1,x,y,z);
}

////////////////////////////////////////////////////////////////////////////////
/// GetN()  returns the number of allocated cells if any.
/// GetN() > 0 shows how many cells
/// can be available via GetP() method.
/// GetN() == 0 then GetP() must return 0 as well

Int_t TPoints3DABC::GetN() const
{
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// GetP()  returns the pointer to the float point array
/// of points if available
/// The number of the available cells can be found via
/// GetN() method.
/// GetN() > 0 shows how many cells

Float_t *TPoints3DABC::GetP() const
{
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// GetXYZ(Float_t *xyz,Int_t idx,Int_t num=1) fills the buffer supplied
/// by the calling code with the points information.
///
///  Input parameters:
///
///  - Float_t *xyz : an external user supplied floating point array.
///  - Int_t    num : the total number of the points to be copied
///                   the dimension of that array the size of the
///                   array is num*sizeof(Float_t) at least
///  - Int_t    idx : The index of the first copy to be taken.
///
///  Return: The pointer to the buffer array supplied

Float_t *TPoints3DABC::GetXYZ(Float_t *xyz,Int_t idx,Int_t num)  const
{
   if (xyz) {
      Int_t size = TMath::Min(idx+num,Size());
      Int_t j=0;
      for (Int_t i=idx;i<size;i++) {
         xyz[j++] = GetX(i);
         xyz[j++] = GetY(i);
         xyz[j++] = GetZ(i);
      }
   }
   return xyz;
}