PK_ERROR_code_t                 PK_SURF_create_blend
(
--- received arguments ---
PK_GEOM_t                       geom1,      --- first underlying geometry
double                          range1,     --- offset from geom1
PK_GEOM_t                       geom2,      --- first underlying geometry
double                          range2,     --- offset from geom2
PK_VECTOR_t                     start,      --- help point for start
PK_VECTOR_t                     end,        --- help point for end
const PK_SURF_create_blend_o_t *options,

--- returned arguments ---
PK_SURF_t                *const blend_surf  --- blend surface
)


This function creates a surface, representing a constant radius rolling ball
blend upon the supplied geometry


Specific Errors:
    PK_ERROR_bad_blend_param       magnitudes of range1 and range2
                                   different
    PK_ERROR_bad_shared_entity     geom1 and geom2 not owned by same part
    PK_ERROR_su_self_intersect     self intersecting blend surface


range1 is the offset from the surface geom1 to the blend spine.
range2 is the offset from the surface geom2 to the blend spine.
range1 and range2 must have the same magnitude (the radius of the rolling
ball).
range1 and range2 are measured in the direction of the surface normal as
returned by PK_SURF_eval_with_normal.

start and end are help points near the blend spine indicating roughly the
extent of the surface.  The offset surfaces may have several intersections
and these points are used to choose the required one.