計(jì)算機(jī)圖形學(xué)實(shí)習(xí)

計(jì)算機(jī)圖形學(xué)實(shí)習(xí)(4)西北農(nóng)林科技大學(xué)實(shí)驗(yàn)報(bào)告學(xué)院名稱:理學(xué)院專業(yè)年級:信計(jì)061姓名:袁金龍學(xué)號:15206012課程名稱:計(jì)算機(jī)圖形學(xué)報(bào)告時(shí)間:2009年5月25日實(shí)驗(yàn)四二維圖形的裁剪一、實(shí)驗(yàn)?zāi)康模杭由顚χ本€段裁剪算法的理解，并能夠掌握一種裁剪算法的編程方法；二、實(shí)驗(yàn)內(nèi)容：1.基本理論線A線線A線B線Cif(e>0)if(dy>=0)y=y+1;endif(dy<0)y=y-1;ende=e-2*abs(dx);endendend%斜率為|k|>=1時(shí)if(abs(dx)<abs(dy))e=-abs(dy);while(abs(y)<=abs(y1))%fprintf('%d,%d\n',x,y);plot(x,y,'r*');axis([-100100-100100]);pause(0.1)gridon;holdon;e=e+2*abs(dx);if(dy>=0)y=y+1;endif(dy<0)y=y-1;endif(e>0)if(dx>=0)x=x+1;endif(dx<0)x=x-1;ende=e-2*abs(dy);endendendholdoff;function[]=zxjq(xwl,xwr,ywb,ywt,x1,y1,x2,y2)subplot(121)%axis([xwl,xwr,ywb,ywt]);zhixian(xwl,ywb,xwl,ywt);holdon;zhixian(xwl,ywt,xwr,ywt);holdon;zhixian(xwr,ywb,xwr,ywt);holdon;zhixian(xwl,ywb,xwr,ywb);holdon;zhixian(x1,y1,x2,y2);title('剪切前的直線')p(1)=-(x2-x1);p(2)=x2-x1;p(3)=-(y2-y1);p(4)=(y2-y1);q(1)=x1-xwl;q(2)=xwr-x1;q(3)=y1-ywb;q(4)=ywt-y1;x=x2-x1;y=y2-y1;ifx==0ifq(1)<0|q(2)<0return;fprintf('直線段在窗口外，可以刪除')elseifq(1)>=0&q(2)>=0fori=3:4ifp(i)<0umax=max(0,q(i)/p(i));endifp(i)>0umin=min(1,q(i)/p(i));endendifumax>uminreturn;elseifumax<=uminx3=x1+umax*(x2-x1);y3=y1+umax*(y2-y1);x4=x1+umin*(x2-x1);y4=y1+umin*(y2-y1);subplot(122);zhixian(xwl,ywb,xwl,ywt);holdon;zhixian(xwl,ywt,xwr,ywt);holdon;zhixian(xwr,ywb,xwr,ywt);holdon;zhixian(xwl,ywb,xwr,ywb);holdon;zhixian(x3,y3,x4,y4);title('剪切后的直線')endendelseify==0ifq(3)<0|q(4)<0return;elseifq(1)>=0&q(2)>=0fori=1:2ifp(i)<0umax=max(0,q(i)/p(i));endifp(i)>0umin=min(1,q(i)/p(i));endendifumax>uminreturn;elseifumax<=uminx3=x1+umax*(x2-x1);y3=y1+umax*(y2-y1);x4=x1+umin*(x2-x1);y4=y1+umin*(y2-y1);subplot(122);zhixian(xwl,ywb,xwl,ywt);holdon;zhixian(xwl,ywt,xwr,ywt);holdon;zhixian(xwr,ywb,xwr,ywt);holdon;zhixian(xwl,ywb,xwr,ywb);holdon;zhixian(x3,y3,x4,y4);title('剪切后的直線')endendelsex~=0|y~=0fori=1:4ifp(i)<0umax=max(0,q(i)/p(i));endifp(i)>0umin=min(1,q(i)/p(i));endendifumax>uminreturn;elseifumax<=uminx3=x1+umax*(x2-x1);y3=y1+umax*(y2-y1);x4=x1+umin*(x2-x1);y4=y1+umin*(y2-y1);subplot(122);zhixian(xwl,ywb,xwl,ywt);holdon;zhixian(xwl,ywt,xwr,ywt);holdon;zhixian(xwr,ywb,xwr,ywt);holdon;zhixian(xwl,ywb,xwr,ywb);holdon;zhixian(x3,y3,x4,y4);title('剪切后的直線')endend%演示例題zxjq(10,80,20,60,20,-20,25,70)3）、結(jié)果顯示在命令窗口中輸入CJ(1,1,6,11,2,7,2,9)三、實(shí)驗(yàn)總結(jié)：直線裁剪算法是計(jì)算機(jī)圖形學(xué)領(lǐng)域的一個(gè)基本問題，提高線裁剪算法的效率在計(jì)算機(jī)圖形學(xué)的各個(gè)應(yīng)用領(lǐng)域中都有著重大的意義。線段與窗口邊界的交點(diǎn)計(jì)算是線裁剪函數(shù)的耗時(shí)部分，本文通過對cohen-sutherland線裁剪算法進(jìn)行了改進(jìn)，從而減少了求交次數(shù)，提高了算法的效率。參