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4 Geometry standards
Fig. 4.12. Bernstein polynomials (Nitschke 2003)
The control points of a B-spline are called knots. If the knots are spaced in equal
intervals the B-spline is unifonn and if not, it is considered non-unifonn.
If a B-spline is a polynomial then it is non-rational. However, if the B-spline is a
ratio of polynomials it is then considered rational.
A Bezier-spline (class GM_Bezier) is a B-spline using Bernstein polynornials for
weighting the influence ofthe control points (knots).
4.3.3.3 Surfaces
A polygon (dass GM]olygon) is a surface patch that is defined by a set of
boundary curves and an underlying surface to which these curves adhere. The default
is that the curves are coplanar and the polygon uses planar interpolation in its interior.
GM_ Triangle
A triangle (class GM _Triangle) is a planar polygon defined by 3 corners.