The abstract class GeometrySurface is the root class of all surface objects. Return the shape for the geometry. Computes the point of parameter (u,v) on this surface Computes the tangent of parameter (u,v) on this geometry Returns the parametric bounds (U1, U2, V1, V2) of this trimmed surface. Returns the global continuity of the surface. Returns true if this patch is periodic in the given parametric direction. Returns true if this patch is periodic in the given parametric direction. Checks if this surface is closed in the u parametric direction. Checks if this surface is closed in the v parametric direction. Returns the period of this patch in the u parametric direction. Returns the period of this patch in the v parametric direction. Returns the parameter on the curve of the nearest orthogonal projection of the point. Returns a B-Spline representation of this surface. The required arguments are: * tolerance * continuity in u (as string e.g. C0, G0, G1, C1, G2, C3, CN) * continuity in v (as string e.g. C0, G0, G1, C1, G2, C3, CN) * maximum degree in u * maximum degree in v * maximum number of segments * precision code (optional, default=0)