ents.Asitstands,thesystemcanatmostprovidezero外文翻译第页continuity,ensuringonlythattwosegmentswilltoucheachother.Forapracticalsoiution,mostdesignsystemsemployacurvedescription.Thetypeofdescriptionemployedprimarilydependsontheamountofcontinuityrequired.Curveslabelledas“quadratics”(suchasthecircular,elliptic,parabolicandhyperbolicarcs)cangivetangentcontinuity;whilst“cubic”curvescanprovidecurvaturecontinuity.Figgivesasummativeillustrationoftheseproperties.Higherordereddescriptionscanprovidebettercontinuity,butthisisachievedattheexpenseofcomputationalefficiencyandmodellingconversionrates.Forreasonsofsimplicity,therefore,curvedescriptionsabovecubicorderarenormallynotusedtomodeloutlinesofshape,includingthatofcharacteroutlines.Whencurvedescriptionsareused,theyareusuallyreferredtoassplines.Thetermsplineoriginatedw连续性提高描述连续性就相对降低了计算效率和模型转换效率,所以字符外形轮廓通常不用三次曲线来模拟。
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