实验一多边形彩色填充实验目的学习并掌握Y-X扫描线算法掌握基于Win32、VisualC++环境下MFC编程绘制图形实验原理对任一条扫描线，确定该扫描线与多边形边的交点位置，自左向右存储，并对每对内部交点间的帧缓存填写指定颜色算法步骤扫描线链表4.边表ET：初始化时建立全局边表（ET）,包含多边形所有边，按边端点的ymin排序存放。即：若该边的下端点为ymin，则该边就放在扫描线ymin对应的链表中。每条扫描线交的多边形的边按其下端点的x坐标增序排列。5.活跃边表AET：与当前扫描线相交的边称为活性边，按与扫描线交点x坐标递增的顺序存放在一个链表中，称此链表为活性边表(AET)实验关键代码CPolyFill::CPolyFill(){m_pEDGEs=NULL;m_pET=NULL;m_pAET=NULL;MinY=10000;MaxY=-1;MinX=10000;MaxX=-1;}CPolyFill::~CPolyFill(){if(m_pEDGEs)delete[]m_pEDGEs;if(m_pET)delete[]m_pET;if(m_pAET)delete[]m_pAET;}//统计多边形各条边的信息，生成Edge结构。voidCPolyFill::BuildEDGEs(){if(m_pEDGEs){delete[]m_pEDGEs;m_pEDGEs=NULL;}m_pEDGEs=newEDGE[m_PtNum];for(inti=0;i<m_PtNum-1;i++){if(m_Pts[i].y>m_Pts[i+1].y){m_pEDGEs[i].Up=m_Pts[i];m_pEDGEs[i].Down=m_Pts[i+1];}else{m_pEDGEs[i].Up=m_Pts[i+1];m_pEDGEs[i].Down=m_Pts[i];}m_pEDGEs[i].EG.Ymax=m_pEDGEs[i].Up.y;m_pEDGEs[i].EG.X=m_pEDGEs[i].Down.x;m_pEDGEs[i].EG.Dx=double((m_pEDGEs[i].Up.x-m_pEDGEs[i].Down.x))/(m_pEDGEs[i].Up.y-m_pEDGEs[i].Down.y);}if(m_Pts[0].y>m_Pts[m_PtNum-1].y){m_pEDGEs[m_PtNum-1].Up=m_Pts[0];m_pEDGEs[m_PtNum-1].Down=m_Pts[m_PtNum-1];}else{m_pEDGEs[m_PtNum-1].Up=m_Pts[m_PtNum-1];m_pEDGEs[m_PtNum-1].Down=m_Pts[0];}m_pEDGEs[m_PtNum-1].EG.Ymax=m_pEDGEs[m_PtNum-1].Up.y;m_pEDGEs[m_PtNum-1].EG.X=m_pEDGEs[m_PtNum-1].Down.x;m_pEDGEs[m_PtNum-1].EG.Dx=double((m_pEDGEs[m_PtNum-1].Up.x-m_pEDGEs[m_PtNum-1].Down.x))/(m_pEDGEs[m_PtNum-1].Up.y-m_pEDGEs[m_PtNum-1].Down.y);}voidCPolyFill::Polygon(CPoint*pts,intcnt){m_Pts=pts;m_PtNum=cnt;BuildEDGEs();//计算出每条多边形边的斜率，Ymax,Xmin等。CreateET();//初始化全局边表InitAET();//初始化活跃边表}voidCPolyFill::CreateET(){GetMinMaxY(MinY,MaxY);if(m_pET){delete[]m_pET;m_pET=NULL;}m_pET=newCArray<Edge,Edge>[MaxY-MinY+1];//AddEDGEtoETfor(inti=0;i<m_PtNum;i++){intscanline=m_pEDGEs[i].Down.y-MinY;m_pET[scanline].Add(m_pEDGEs[i].EG);}//多边形的边排序：Sortaccording