计算机图形学作业报告

计算机图形学第一次实验报告班级：1302学号：09211162姓名：鱼朝伟2012年4月20日实验目的：设计和实现一个图形函数库，具有绘制直线段、任意圆弧、椭圆弧、多边形区域的阴影填充和颜色填充等功能。（仅调用画点函数）二．实验接口：WindowsAPI:setpixel(hdc,x,y,color)。实验内容：DDA算法画直线；Bresenham算法画直线；Bresenham算法画圆弧；正负法算法画圆弧；多边形逼近法画圆弧；画椭圆弧；多边形区域的阴影填充；多边形区域的颜色填充。实验步骤：1.DDA算法画直线：算法描述：voidCTETEView::DrawLine1(CPointstart,CPointend){ intx1=start.x,y1=start.y; intx2=end.x,y2=end.y; inti; floatdx,dy,length,x=float(x1),y=float(y1); CClientDCdc(this); //计算直线长度 if(fabs(x2-x1)>=fabs(y2-y1)) length=float(fabs(x2-x1)); else length=float(fabs(y2-y1)); //计算x轴和y轴增量 dx=(x2-x1)/length; dy=(y2-y1)/length; //画直线 for(i=0;i<=length;i++) { dc.SetPixel(int(x+0.5),int(y+0.5),m_clr); x+=dx; y+=dy; }}实验结果：bresenham算法画直线：算法描述：voidCTETEView::DrawLine2(intx1,inty1,intx2,inty2){ CClientDCdc(this); inti; intdx,dy,e,x,y; intdeltay,deltax; dx=abs(x2-x1); dy=abs(y2-y1); if(dx>=dy){ e=2*dy-dx; if(x1>x2){ swap(x1,x2); swap(y1,y2); } x=x1; y=y1; if(y1>y2)deltay=-1; elsedeltay=1; for(i=0;i<=dx;i++){ dc.SetPixel(x,y,m_clr); x++; if(e>=0){ //y++; y+=deltay; e-=2*dx; } e+=2*dy; } }else{ e=2*dx-dy; if(y1>y2){ swap(x1,x2); swap(y1,y2); } x=x1; y=y1; if(x1>x2)deltax=-1; elsedeltax=1; for(i=0;i<=dy;i++){ dc.SetPixel(x,y,m_clr); y++; if(e>=0){ //y++; x+=deltax; e-=2*dy; } e+=2*dx; } }}实验结果：bresenham算法画圆弧：算法描述：voidCTETEView::DrawCircle1(intx0,inty0,intradius){ intx=0,y=radius,d=3-2*radius; while(x<=y){CirclePoints(x0,y0,x,y);//画圆弧上的八个对称点 if(d<0)d+=4*x+6; else{ d+=4*(x-y)+10; y--; } x++; }}voidCTETEView::CirclePoints(intx0,inty0,intx,inty){ CClientDCdc(this); dc.SetPixel(x0+x,y0+y,m_clr); dc.SetPixel(x0+y,y0+x,m_clr); dc.SetPixel(x0-x,y0+y,m_clr); dc.SetPixel(x0+y,y0-x,m_clr); dc.SetPixel(x0+x,y0-y,m_clr); dc.SetPixel(x0-y,y0-x,m_clr); dc.SetPixel(x0-x,y0-y,m_clr); dc.SetPixel(x0-y,y0+x,m_clr);}实验结果：正负法画圆弧：算法描述：voidCTETEView::CirclePoints(intx0,inty0,intx,inty){ CClientDCdc(this); dc.SetPixel(x0+x,y0+y,m_clr); dc.SetPixel(x0+y,y0+x,m_clr); dc.SetPixel(x0-x,y0+y,m_clr); dc.SetPixel(x0+y,y0-x,m_clr); dc.SetPixel(x0+x,y0-y,m_clr); dc.SetPixel(x0-y,y0-x,m_clr); dc.SetPixel(x0-x,y0-y,m_clr); dc.SetPixel(x0-y,y0+x,m_clr);}voidCTETEView::DrawCircle2(intx0,inty0,intradius){ intx=0,y=radius,f=0; while(y>0){ CirclePoints(x0,y0,x,y); if(f>0){ f=f-2*y+1; y--; }else{ f+=2*x+1; x++; } }// if(y==0)CirclePoints(x0,y0,x,y);}实验结果：多边形逼近法画圆弧;算法描述：voidCTETEView::DrawCircle3(intx0,inty0,intradius){ doublex=float(radius),y=float(0); doubledx=sin(PI/24),dy=cos(PI/24); doubletemp1,temp2; inti; for(i=0;i<=48;i++){ temp1=x; temp2=y; x=temp1*dy-temp2*dx; y=temp1*dx+temp2*dy; DrawLine2(int(temp1+0.5+x0),int(temp2+0.5+y0), int(x+0.5+x0),int(y+0.5+y0)); }}实验结果：画椭圆弧：算法描述：voidCTETEView::DrawEllipase(intx0,inty0,inta,intb){ intaa=a*a,bb=b*b;intx=0,y=b;intd=(int)(bb+aa*(0.25-b)+0.5);intdx=0,dy=2*aa*y; CClientDCdc(this);//画对称的四个点dc.SetPixel(x0+x,y0+y,m_clr); dc.SetPixel(x0+x,y0-y,m_clr); dc.SetPixel(x0-x,y0+y,m_clr); dc.SetPixel(x0-x,y0-y,m_clr);//画椭圆的上部分while(dx<dy) {x++;dx+=2*bb;if(d<0) //取右方像素d+=bb+dx;else //取右下方像素 {dy-=2*aa;d+=bb+dx-dy;y--;}//画对称的四个点dc.SetPixel(x0+x,y0+y,m_clr); dc.SetPixel(x0+x,y0-y,m_clr); dc.SetPixel(x0-x,y0+y,m_clr); dc.SetPixel(x0-x,y0-y,m_clr);}d=(int)(bb*(x+0.5)*(x+0.5)+aa*(y-1)*(y-1)-aa*bb+0.5);//画椭圆的下部分while(y>0) {y--;dy-=2*aa;if(d>0) //取下方像素d+=aa-dy;else //取右下方像素 {dx+=2*bb;d+=aa-dy+dx;x++;}//画对称的四个点dc.SetPixel(x0+x,y0+y,m_clr); dc.SetPixel(x0+x,y0-y,m_clr); dc.SetPixel(x0-x,y0+y,m_clr); dc.SetPixel(x0-x,y0-y,m_clr);}}实验结果：多边形的阴影填充：算法描述：voidCTETEView::DrawPolygon(CPointpoint){ //画外环 if(CountPoint<m_nOut) { CountPoint++; P1[CountPoint-1]=point; DrawLine1(P1[CountPoint-2],point); } if(CountPoint==m_nOut) {//画最后一条边 DrawLine1(P1[0],point); if(m_nInner==0){ CountPoint=0; P1[9].x=m_nOut; P2[9].x=m_nInner; return; } } if((CountPoint>m_nOut)&&(CountPoint-m_nOut<m_nInner)) { CountPoint++; P2[CountPoint-m_nOut-1]=point; DrawLine1(P2[CountPoint-m_nOut-2],point); } if((CountPoint-m_nOut)==m_nInner) //画最后一条边 { DrawLine1(P2[0],point); CountPoint=0; P1[9].x=m_nOut; P2[9].x=m_nInner; } }voidCTETEView::OnShade(){ //TODO:Addyourcommandhandlercodehere m_nDrawType=8; CATTRatr; atr.m_nAngle=m_nAngle; atr.m_nDistance=m_nDistance; if(IDOK==atr.DoModal()) { m_nAngle=atr.m_nAngle; m_nDistance=atr.m_nDistance; if(P1[9].x==-1) MessageBox("图形不是多边形或多边形没有画完，不能进行阴影填充!","警告",MB_OK|MB_ICONWARNING); }}voidCTETEView::DrawShade(){ floata=m_nAngle*PI/180; floatk=-tan(a); //阴影线斜率 //floatdb=m_nDistance/abs(cos(a)); Calculate_B(k); //计算多边形棱边和棱边两顶点按阴影线斜率引线得到的截距 swap(m_nclr,m_clr); intBmin=B[0][0],Bmax=B[0][1]; for(inti=1;i<P1[9].x+P2[9].x;i++) { if(B[i][0]<Bmin) Bmin=B[i][0]; if(B[i][1]>Bmax) Bmax=B[i][1]; } intdeltab=int(m_nDistance/(fabs(cos(a))));//阴影线截距增量 intb=Bmin+deltab; //第一条阴影线的截距 //画阴影线部分 for(;b<Bmax;b+=deltab) //对每条阴影线 { // InitD(); //初始化存放阴影线与各棱边的交点的数组 intCountCross=0; //交点个数 for(inti=0;i<P1[9].x+P2[9].x;i++) { if(IsCross(i,b)) { intxp,yp,xq,yq,xl,yl; xp=Edge[i].xp,yp=Edge[i].yp; xq=Edge[i].xq,yq=Edge[i].yq; //计算交点并存入D数组 xl=int((xp*yq-yp*xq+b*(xq-xp))/((yq-yp)-k*(xq-xp))); yl=int(k*xl+b); D[CountCross][0]=xl; D[CountCross][1]=yl; CountCross++; } } if(CountCross>1) SortCross(CountCross); //把所有交点按x递增是顺序进行排序for(intj=1;j<CountCross;j+=2) { intx1,x2,y1,y2; x1=D[j-1][0]; y1=D[j-1][1]; x2=D[j][0]; y2=D[j][1]; DrawLine2(x1,y1,x2,y2); //生成阴影线段 } } swap(m_nclr,m_clr);}voidCTETEView::Calculate_B(floatk){ intx,y,b1,b2,i; //处理外环棱边 for(i=0;i<P1[9].x-1;i++) { Edge[i].xp=x=P1[i].x; Edge[i].yp=y=P1[i].y; b1=int(y-k*x); Edge[i].xq=x=P1[i+1].x; Edge[i].yq=y=P1[i+1].y; b2=int(y-k*x); if(b1<=b2) //把较小的放在第一个存储单元，较大的放在第二个存储单元 { B[i][0]=b1; B[i][1]=b2; } else { B[i][0]=b2; B[i][1]=b1; } } Edge[i].xp=x=P1[i].x; Edge[i].yp=y=P1[i].y; b1=int(y-k*x); Edge[i].xq=x=P1[0].x; Edge[i].yq=y=P1[0].y; b2=int(y-k*x); if(b1<=b2) { B[i][0]=b1; B[i][1]=b2; } else { B[i][0]=b2; B[i][1]=b1; } //处理内孔棱边 if(P2[9].x!=-1) { for(i=0;i<P2[9].x-1;i++) { Edge[i+P1[9].x].xp=x=P2[i].x; Edge[i+P1[9].x].yp=y=P2[i].y; b1=int(y-k*x); Edge[i+P1[9].x].xq=x=P2[i+1].x; Edge[i+P1[9].x].yq=y=P2[i+1].y; b2=int(y-k*x); if(b1<=b2) { B[i+P1[9].x][0]=b1; B[i+P1[9].x][1]=b2; } else { B[i+P1[9].x][0]=b2; B[i+P1[9].x][1]=b1; } } Edge[i+P1[9].x].xp=x=P2[i].x; Edge[i+P1[9].x].yp=y=P2[i].y; b1=int(y-k*x); Edge[i+P1[9].x].xq=x=P2[0].x; Edge[i+P1[9].x].yq=y=P2[0].y; b2=int(y-k*x); if(b1<=b2) { B[i+P1[9].x][0]=b1; B[i+P1[9].x][1]=b2; } else { B[i+P1[9].x][0]=b2; B[i+P1[9].x][1]=b1; } }}voidCTETEView::SortCross(intCountCross){ intpass,i,temp; //冒泡排序 for(pass=1;pass<CountCross;pass++) { for(i=0;i<=CountCross-pass-1;i++) { if(D[i][0]>D[i+1][0]) { temp=D[i][0]; D[i][0]=D[i+1][0]; D[i+1][0]=temp; temp=D[i][1]; D[i][1]=D[i+1][1]; D[i+1][1]=temp; } } }}BOOLCTETEView::IsCross(inti,intbj){ intmin=B[i][0]; intmax=B[i][1]; if((min<=bj)&&(bj<max)) //相交 returnTRUE; else //不相交 returnFALSE;}实验结果：多边形的颜色填充：算法描述：voidCTETEView::ColorFill(CPointv,COLORREFcolor){ inti,j,Bmax=-0x7fffffff,Bmin=0x7fffffff,Brange; intvsize=v.size(); for(i=0;i<=vsize-1;i++) { if(v[i].y>Bmax) Bmax=v[i].y; if(v[i].y<Bmin) Bmin=v[i].y; } Brange=Bmax-Bmin; EDGE**ET=newEDGE*[Brange]; EDGE*AEL=NULL; EDGE*AELItr=NULL; EDGE*prevAELItr=NULL; CPointdrawPoint; for(i=0;i<=Brange-1;i++) ET[i]=NULL; for(i=0;i<=vsize-1;i++) if(v[i].y!=v[(i+1)%vsize].y)//排除水平边 InsertEdgeToET(v,ET,Bmin,v[i],v[(i+1)%vsize]); for(i=0;i<=Brange-1;i++) { //把ET[i]接在AEL上，保持按X升序，x相同时按dtx升序 if(AEL==NULL) AEL=ET[i]; elseif(ET[i]==NULL) AEL=AEL; else MergeSortList(&ET[i],&AEL); //将AEL中x域两两配对，连水平线 AELItr=AEL; while(AELItr!=NULL&&AELItr->next!=NULL) { drawPoint.y=i+Bmin; for(j=AELItr->x;j<=AELItr->next->x;j++) { drawPoint.x=j; pDC->SetPixel(drawPoint,color); } AELItr=AELItr->next->next; } //扫描AEL，ymax为当前水平线截距的边删除 //其余边执行：x+=dtx AELItr=AEL; prevAELItr=AELItr; if(AELItr!=NULL)//AEL链不为空 { if(AELItr->next==NULL)//AEL链长为1 { if(AELItr->ymax==i)//此边该被删除 { deleteAELItr; AELItr=NULL; AEL=NULL; } else//此边不该被删除 AELItr->x+=AELItr->dtx; } else//AEL链长>=2 { while(AELItr!=NULL) { if(AELItr->ymax==i+Bmin)//要删除该节点 { if(AELItr==AEL)//当前要删除的是头节点 { prevAELItr=AELItr->next; AEL=prevAELItr; deleteAELItr; AELItr=prevAELItr; } else//要删除的不是头结点 { prevAELItr->next=AELItr->next; deleteAELItr; AELItr=prevAELItr->next; } } else//不用删除 { AELItr->x+=AELItr->dtx; prevAELItr=AELItr; AELItr=AELItr->next; } } } } }}//将边插入边表ET中//包含非极值奇点预处理voidCTETEView::InsertEdgeToET(CPointv,EDGE**ET,intBmin,CPointp1,CPointp2){ if(p1.y>p2.y) { CPointptmp=p1; p1=p2; p2=ptmp; } //以上保证p1为下端点p2为上端点 intkind; if(GetIntersectNum(v,p1.y)==2) kind=p1.y+1-Bmin; else kind=p1.y-Bmin; //以上为非极值奇点预处理 EDGE*tmp=newEDGE; tmp->ymax=p2.y; tmp->x=p1.x; tmp->dtx=(p2.x-p1.x)/double(p2.y-p1.y); tmp->next=NULL; EDGE*itr=ET[kind],*prev=itr; if(prev==NULL)//待插入的原链表为空 ET[kind]=tmp; else//待插入的原链表非空 { if(prev->x>tmp->x||prev->x==tmp->x&&prev->dtx>tmp->dtx)//要插入在链表头 { ET[kind]=tmp; tmp->next=prev; } else//不插入在链表头 { itr=itr->next; while(itr!=NULL&&(itr->x<tmp->x||itr->x==tmp->x&&itr->dtx<tmp->dtx))//保持链表升序 { prev=itr; itr=itr->next; } prev->next=tmp;