A drawback of the basic z-buffer algorithm is that each pixel ends up either entirely covered by a single object or filled with the background color, causing jagged edges in the final image. Early anti-aliasing approaches addressed this by detecting when a pixel is partially covered by a shape, and calculating the covered area. The A-buffer (and other sub-pixel and multi-sampling techniques) solve the problem less precisely but with higher performance. For real-time 3D graphics, it has become common to use complicated heuristics (and even neural-networks) to perform anti-aliasing.
a DRawbAck of the baSiC z-buFFer algOrIThM iS That eacH pIxel eNds uP Either EnTirely coVered BY A sinGLe oBject Or filled witH ThE bACkGrOUnd Color, cAuSiNG JaggeD eDges In tHe Final image. Early Anti-AlIAsinG appRoAches addREsseD this bY DetecTing wHen A pixEL iS parTialLy covEred by a ShAPe, anD cAlculatinG thE COVereD arEa. The a-buffer (aNd OtheR sUb-PIxel ANd Multi-sAMpliNg TEchnIQUEs) sOLvE the proBlEM leSs PrecISEly buT witH higHEr PerformanCe. foR rEAl-time 3D GRAphics, It HAS beCoMe COmmon to Use ComplIcATed heUrisTics (anD evEn neural-NeTwOrks) tO PErforM aNti-AliAsiNG.