-static gp_Circ2d* newCirc2d(const std::shared_ptr<GeomAPI_Pnt2d>& theFirstPoint,
- const std::shared_ptr<GeomAPI_Pnt2d>& theSecondPoint,
- const std::shared_ptr<GeomAPI_Pnt2d>& theThirdPoint)
-{
- gp_XY aFirstPnt(theFirstPoint->x(), theFirstPoint->y());
- gp_XY aSecondPnt(theSecondPoint->x(), theSecondPoint->y());
- gp_XY aThirdPnt(theThirdPoint->x(), theThirdPoint->y());
-
- gp_XY aVec12 = aSecondPnt - aFirstPnt;
- gp_XY aVec23 = aThirdPnt - aSecondPnt;
- gp_XY aVec31 = aFirstPnt - aThirdPnt;
-
- // coefficients to calculate center
- double aCoeff1, aCoeff2, aCoeff3;
-
- // square of parallelogram
- double aSquare2 = aVec12.Crossed(aVec23);
- aSquare2 *= aSquare2 * 2.0;
- if (aSquare2 < 1.e-20) {
- // if two points are equal, build a circle on two different points as on diameter
- double aSqLen12 = aVec12.SquareModulus();
- double aSqLen23 = aVec23.SquareModulus();
- double aSqLen31 = aVec31.SquareModulus();
- if (aSqLen12 < Precision::SquareConfusion() &&
- aSqLen23 < Precision::SquareConfusion() &&
- aSqLen31 < Precision::SquareConfusion())
- return NULL;
- aCoeff1 = aCoeff2 = aCoeff3 = 1.0 / 3.0;
- }
- else {
- aCoeff1 = aVec23.Dot(aVec23) / aSquare2 * aVec12.Dot(aVec31.Reversed());
- aCoeff2 = aVec31.Dot(aVec31) / aSquare2 * aVec23.Dot(aVec12.Reversed());
- aCoeff3 = aVec12.Dot(aVec12) / aSquare2 * aVec31.Dot(aVec23.Reversed());
- }
- // center
- gp_XY aCenter = aFirstPnt * aCoeff1 + aSecondPnt * aCoeff2 + aThirdPnt * aCoeff3;
- // radius
- double aRadius = (aFirstPnt - aCenter).Modulus();