圖形學(xué)期末期末復(fù)習(xí)

1、7mxyxxyyendend00FIf |m|1, yi+1=mxi+1+b=m(xi+x)+b=yi+mx x=1, yi+1=yi+mFIf |m|1, y=1, xi+1=xi+1/mF 掃描轉(zhuǎn)換開始時(shí), 取直線始點(diǎn)(x0, y0)作為初始坐標(biāo)。算法描述如下: m為直線的斜率 如圖，起始點(diǎn)為 (x0,y0), 對(duì)每一列(x坐標(biāo))確定像素，其行掃描線y最接近直線. 假定(xi,yi)已經(jīng)被顯示。下一步要確定的是在xi+1列中是哪個(gè)像素被顯示 (xi+1,yi) ? (xi+1,yi+1)?) 10(, 1, 0, 0,),(),(01011100mmyxyxyxifyyyxxxbmxyyx

2、endyxstartincincXY(x , y)(y , x)(y , x)(x , y)( x , y)( y , x)( y , x)( x , y)OR452R圖 4.5 圓的對(duì)稱性算法比較l逐點(diǎn)法簡(jiǎn)單，速度慢，效率低110010011yxttyxyx11000cossin0sincos1yxyx110000001yxSSyxyx)/( ,BAarctg )()()()()(xxtTRreflectionFRtTM)()()(,zyxzyxzyxtttTsssStttTM圖形變換矩陣S可以是旋轉(zhuǎn)、比例等變換)()()()()(RRRRRMminmaxminminmaxminminmax

3、minminmaxminvvvvwwwwvvvvwwwwyyyyyyyyxxxxxxxx1100001wwyxvvyxbSaSyx窗口到視區(qū)的變換是比例變換和平移變換的復(fù)合變換(200,200)B(160,180)C(180,140)A(140,140)(120,120)xWOWyWyS(60,60)OSxS(100,100)B*C*A*圖8-6 窗口區(qū)域代碼U1=max(Ua,Ub,0)U2=min(Uc,Ud,1)時(shí)為正投影當(dāng)時(shí)為斜投影當(dāng)00100000000sin100cos011111LLLLMpar視點(diǎn)在Z軸投影面為XOY平面1000000001000011dperM (a) 一點(diǎn)透

4、視； (b) 二點(diǎn)透視； (c) 三點(diǎn)透視滅點(diǎn)滅點(diǎn)滅點(diǎn)滅點(diǎn)滅點(diǎn)滅點(diǎn)(a)(b)(c)滅點(diǎn)：任何一束不平行于投影平面的平行線的透視變換將匯聚為一點(diǎn)),()()()(000,zyxTRRRMxyzvcwcwvcwcvPMP,10002000yy20002minmaxminmaxminmaxminmaxminmaxminmaxfarnearfarnearfarnearzzzzzzywywywywwwxwxwxwxwxwxwT正交規(guī)范),( ),(yxfzxfy0),( , 0),(zyxFyxF)(),(),(,)()()()(tztytxyxtCtzztyytxx空間曲線參數(shù)表示法 )()()()

5、()()( 1 11tCtCtCtCtCtCiiiiii0 )()(0 )()()()( 1 11tCtCtCtCtCtCiiiiii)(),(),(z,)()()()(u,vzu,vyu,vxyxu,vPu,vzzu,vyyu,vxx空間曲面基函數(shù)控制點(diǎn))()()(0tBPtBPtCiintiininiitBPtC0,)()(, 2 , 1 , 0,niPi, 2 , 1 , 0,niPi 0001003303631331 1 )1 (3 )1 (3 )1()( 3001022121 1 )1 (2 )1()( 2 )1()( 13210233210322321022102210PPPPtt

6、tPPPPtttttttCnPPPttPPPtttttCnPP tttCnnPCPC) 1 ( , )0(0)-() 1 ( , )-()0(101nnPPnCPPnC)()(),()()(,00,0,0vBuBPvuSvBPPuBPSnjmiminjjinjnjjiimimiiLocal PropertyExplicit solutionInterpolation n 由B樣條線性組合而來，繼承了一般樣條函數(shù)的優(yōu)點(diǎn)，如連續(xù)性，對(duì)稱性和規(guī)范性。n 同時(shí)又具備局部性、插值性、顯式不求解特性 0001003303631331 1 )1 (3 )1 (3 )1()( 332102332103223PPPPtttPPPPtttttttCnnspdpaasdeKIKIKIIIIIcoscosniinsipniidipaasdeKIKIKIIIII1),(1),(coscos上式所進(jìn)行的光強(qiáng)計(jì)算只是假定只有一個(gè)點(diǎn)光源的，若場(chǎng)景中有多個(gè)點(diǎn)光源，則可以在任一點(diǎn)光源處迭加各個(gè)光源所產(chǎn)生的光源效果，這就是Phong光照明模型sBsGsRsdBdGdRdaBaGaRasBsGsRsdBdGdRdaBaGaRaKKKKKKKKKKKKIIIIIIIIIIIIniinsBipBniidBipBaBaBBniinsGipGniidGipGaGaGGniinsRipRniid