occt/src/Aspect/Aspect_CircularGrid.cxx

// Modified	23/02/98 : FMN ; Remplacement PI par Standard_PI

#define CSR577  //GG 25/09/00 Avoid to have unaccuracy coordinates computation
//              when the grid is activated.

#define OCC192_193 // jfa 27/02/2002
// for big rotation angles - error of negative values expression in round numbers

#define xTRACE

#include <Aspect_CircularGrid.ixx>
#include <Aspect_Grid.hxx>
#include <Standard_NumericError.hxx>
Aspect_CircularGrid::Aspect_CircularGrid
     (const Quantity_Length aRadiusStep,
      const Standard_Integer aDivisionNumber,
      const Quantity_Length anXOrigin,
      const Quantity_Length anYOrigin,
      const Quantity_PlaneAngle aRotationAngle)
:Aspect_Grid(anXOrigin,anYOrigin,aRotationAngle),myRadiusStep(aRadiusStep),
myDivisionNumber(aDivisionNumber) {
   }

void Aspect_CircularGrid::SetRadiusStep(const Standard_Real aRadiusStep) {
  Standard_NegativeValue_Raise_if(aRadiusStep < 0., "invalid radius step");
  Standard_NullValue_Raise_if(aRadiusStep == 0. , "invalid radius step");
  myRadiusStep= aRadiusStep;
  Init();
  UpdateDisplay();
}
void Aspect_CircularGrid::SetDivisionNumber(const Standard_Integer aNumber) {
  Standard_NegativeValue_Raise_if(aNumber < 0., "invalid division number");
  Standard_NullValue_Raise_if(aNumber == 0. , "invalid division number");
  myDivisionNumber = aNumber;
  Init();
  UpdateDisplay();
}
void Aspect_CircularGrid::SetGridValues
     (const Quantity_Length theXOrigin,
      const Quantity_Length theYOrigin,
      const Quantity_Length theRadiusStep,
      const Standard_Integer theDivisionNumber,
      const Quantity_PlaneAngle theRotationAngle) {
  myXOrigin = theXOrigin;
  myYOrigin = theYOrigin;
  Standard_NegativeValue_Raise_if(theRadiusStep < 0., "invalid radius step");
  Standard_NullValue_Raise_if(theRadiusStep == 0. , "invalid radius step");
  myRadiusStep= theRadiusStep;
  Standard_NegativeValue_Raise_if(theDivisionNumber < 0., "invalid division number");
  Standard_NullValue_Raise_if(theDivisionNumber == 0. , "invalid division number");
  myDivisionNumber = theDivisionNumber;
  myRotationAngle = theRotationAngle;
  Init();
  UpdateDisplay();
}
void Aspect_CircularGrid::Compute(const Quantity_Length X,
			 const Quantity_Length Y,
			 Quantity_Length& gridX,
			 Quantity_Length& gridY) const {

#ifdef TRACE 
  if( X == 0. || Y == 0. ) {
      cout << " Aspect_CircularGrid" << endl;
  }
#endif
  Standard_Real xo = XOrigin();
  Standard_Real yo = YOrigin();
  Standard_Real d = Sqrt( (xo-X)*(xo-X) + (yo-Y)*(yo-Y) );
  Standard_Integer n = (Standard_Integer ) ( d/myRadiusStep + 0.5 ) ;
  Standard_Real radius = Standard_Real(n) * myRadiusStep;
  Standard_Real cosinus = (X-xo)/d;
  Standard_Real a = ACos(cosinus);
  Standard_Real ra = RotationAngle();
  if ( Y < yo ) a = 2 * M_PI - a;
#ifdef OCC192_193
  n = (Standard_Integer ) ((a-ra)/myAlpha + Sign(0.5, a-ra)) ;
#else
  n = (Standard_Integer ) ((a-ra)/myAlpha +0.5 ) ;
#endif

#ifdef CSR577
  Standard_Real cs=0,sn=0;
  Standard_Boolean done = Standard_False;
  Standard_Integer nmax = 2*myDivisionNumber;
  Standard_Integer nquad,qmax;

  if( ra == 0. ) {
    nquad = 4; qmax = nmax/nquad;
    if( (n == 0) || (!(nmax % nquad) && !(n % qmax)) ) {
      Standard_Integer q = n/qmax;
      switch (q) {
	default:
        case 0:
          cs = 1.; sn = 0.;
          break;
        case 1:
          cs = 0.; sn = 1.;
          break;
        case 2:
          cs = -1.; sn = 0.;
          break;
        case 3:
          cs = 0.; sn = -1.;
          break;
      }
      done = Standard_True;
    } else {
      nquad = 2; qmax = nmax/nquad;
      if( !(nmax % nquad) && !(n % qmax) ) {
        Standard_Integer q = n/qmax;
        switch (q) {
	  default:
          case 0:
            cs = 1.; sn = 0.;
            break;
          case 1:
            cs = -1.; sn = 0.;
            break;
        }
        done = Standard_True;
      }
    }
  } 

  if( !done ) {
    Standard_Real ang = ra + Standard_Real(n)*myAlpha;
    cs = Cos(ang); sn = Sin(ang);
  }
#else
  Standard_Real ang = RotationAngle()+ Standard_Real(n)*myAlpha;
  Standard_Real cs = Cos(ang);
  Standard_Real sn = Sin(ang);  
#endif
  gridX = xo + cs * radius;
  gridY = yo + sn * radius;
#ifdef TRACE
    cout << "Aspect_CircularGrid::Compute (" << Quantity_Length (X) << ", "
         << Quantity_Length (Y) << ", " << Quantity_Length (gridX) << ", "
         << Quantity_Length (gridY) << ")" << endl;
#endif
}

Quantity_Length Aspect_CircularGrid::RadiusStep() const {
  return myRadiusStep;
}

Standard_Integer Aspect_CircularGrid::DivisionNumber () const {
return myDivisionNumber;
}

void Aspect_CircularGrid::Init () {
  myAlpha = M_PI / Standard_Real(myDivisionNumber);
  myA1 = Cos(myAlpha); myB1=Sin(myAlpha);
}