q3d指导书 OverviewofDraw Primitives Insolidmodeling,thebasicelementorobjectisoftencalledaprimitive. Examplesofprimitivesareboxes,cylinders,rectangles,circles,etc.There aretwotypesofprimitives:3Dprimitivesorsolids,and2Dprimitivesor surfaces.Byplacingacollect