sgCObject* sgSurfaces::Coons(const sgC2DObject& firstSide, const sgC2DObject& secondSide, const sgC2DObject& thirdSide, const sgC2DObject* fourthSide)
Creates a Coons surface from three or four boudary contours. The contours must be not closed and not self-intersecting. The contours end points must coincide with the end points of the neighboring contours, i.e. form a closed area.
firstSide - first boundary contour.
secondSide - second boundary contour. An end point must coincide with an end point of the previous argument - firstSide.
thirdSide - second boundary contour. An end point must coincide with the end point of the previous contour (secondSide) which doesn't coincide with the end point of the firstSide. If the next argument (fourthSude) is NULL, the second end point of thirdSide must coincide with a free end point of the first contour.
fourthSide - second boundary contour. May be NULL. One end point must coincide with the end point of the previous contour (thirdSide), and another one - with the free end point of the first contour.
Returns the pointer to a newly created object. If the function fails NULL is returned.