Exercises2计算机图形学答案.pdf

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1、Chapter2OverviewofGraphicsSystemsExercisequestionsforthischapterinvestigatethecharacteristicsandapplicationsofcomputer-graphicshardwarecomponents,thegeneralcomputer-graphicssoftwareconcepts,andfeaturesoftheOpenGLlibraries.Exercises2-1.Operatingcharacteristicsfordisplaytechnologiesarediscu

2、ssedinSections2-1through2-3andinthereferencescitedattheendofthechapter.2-2.ApplicationsappropriateforthevariousdisplaytechnologiesarediscussedinSections2-1through2-3andinthelistedreferences.2-3.Asystemmanualcanbeconsultedtoobtainscreendimensionsandthenumberofpixelpositionsthatcanbedisplay

3、edinthexandydirections.Ifxandyscreendimensionsarenotlisted,theycanbemeasured.Theratioofpixelpositionstoscreendimensionsgivestheresolutionsforthehorizontalandverticaldirections.Aspectratioistheratiooftheyandxresolutions.Alternatively,resolutioncanbedeterminedbydisplayingequal-pixel,straigh

4、t-lineseg-mentsinthexandydirectionsandmeasuringthelengthofeachline.Forexample,if100-pixellinesinthexandydirectionsmeasure4cmand5cm,respec-tively,then100xresolution=pixelspercm4100yresolution=pixelspercm5andyresolution4aspectratio==xresolution534CHAPTER2.OVERVIEWOFGRAPHICSSYSTEMSToadjustdi

5、mensionsofobjectstomaintainrelativeproportions,wecanmaketheadjust-mentseithertotheverticalortothehorizontaldimensions.Thatis,verticaldimensionscanbescaledbyafactorof4/5,orhorizontaldimensionscanbescaledbyafactorof5/4.2-4.Frame-buffersizeforeachofthesystemsis640×480×12bits÷8bitsperbyte=450K

6、B1280×1024×12bits÷8bitsperbyte=1920KB2560×2048×12bits÷8bitsperbyte=7680KBFor24bitsofstorageperpixel,eachoftheabovevaluesisdoubled.2-5.Storageneededfortheframebufferis800×1000×6bits÷8bitsperbyte≈486KB2-6.Thetimestoloadthetwoframebuffersare640×480×12bits÷105bitspersec≈36.9secand1280×1024×24bi

7、ts÷105bitspersec≈314.6sec≈5.24min2-7.Totalbitsintheprinterframebufferis8.5×11×3002≈8.4×106bitsTherefore,loadingtimeis8.4×106bits≈0.263sec32×106bps2-8.Forthe640by480system,theaccessrateis640×480×60=1.8432×107pixelspersecThus,accesstimeisapproximately54nanosecondsperpi