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4 Geometry standards
Fig. 4.15. GM_Cone
A cone (class GM _ Cone) is a gridded surface given as a family of conic sections
whose controlPoints vary linearly. That means that the control points defining the
cone in figure 4.15 lie on three straight lines.
GM_Cylinder
Fig. 4.16. GM_Cylinder
A cylinder (class GM _ Cylinder) is a gridded surface given as a family of circles
whose positions vary along a set of parallel lines, keeping the cross sectional horizontal curves of a constant shape.