TPoints3DABC.cxx

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// @(#)root/g3d:$Id: TPoints3DABC.cxx 21394 2007-12-17 08:57:17Z couet $
// Author: Valery Fine(fine@mail.cern.ch)   04/05/99

// @(#)root/g3d:$Id: TPoints3DABC.cxx 21394 2007-12-17 08:57:17Z couet $
// Author: Valery Fine(fine@mail.cern.ch)   24/04/99

#include "TPoints3DABC.h"
#include "TMath.h"

ClassImp(TPoints3DABC)

//______________________________________________________________________________
/* Begin_Html
<center><h2>The TPoints3DABC class</h2></center>
Abstract class to define Arrays of 3D points.
End_Html */



//______________________________________________________________________________
Int_t TPoints3DABC::Add(Float_t x, Float_t y, Float_t z)
{
   // Add one 3D point defined by x,y,z to the array of the points
   // as its last element

   return AddLast(x,y,z);
}


//______________________________________________________________________________
Int_t TPoints3DABC::AddLast(Float_t x, Float_t y, Float_t z)
{
   // Add one 3D point defined by x,y,z to the array of the points
   // as its last element

   return SetNextPoint(x,y,z);
}


//______________________________________________________________________________
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 )
{
   // 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:
   //
   //    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);

   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));
}


//______________________________________________________________________________
Int_t TPoints3DABC::SetNextPoint(Float_t x, Float_t y, Float_t z)
{
   // Add one 3D point defined by x,y,z to the array of the points
   // as its last element

   return SetPoint(GetLastPosition()+1,x,y,z);
}


//______________________________________________________________________________
Int_t TPoints3DABC::GetN() const
{
   // 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

   return 0;
}


//______________________________________________________________________________
Float_t *TPoints3DABC::GetP() const
{
   // GetP()  returns the pointer to the float point array
   //         of points if available
   //         The number of the available celss can be found via
   //         GetN() method.
   //         GetN() > 0 shows how many cells

   return 0;
}


//______________________________________________________________________________
Float_t *TPoints3DABC::GetXYZ(Float_t *xyz,Int_t idx,Int_t num)  const
{
   // 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

   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;
}

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