**Definition**: Object defined by F>=0, where F is a B-spline function of three variables

- Control points of the cubic B-spline volume. Only the fourth coordinnate is used

: Cubic BSpline blending function.

**Call**: hfCubicBSplineF(x,l,m,n,bbox,ctr_pts);

**Parameters**:

x - point coordinates

l,m,n - number of control points on each axis

bbox - array defining the bounding box of the object

ctr_pts - array of values for each control point

**Test file**: bsplinef.hf