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主题：C++多边形扫描转换算法 作者：白々哉 时间：2011-06-11 17:06 |
最近学习计算机图形学,写了个多边形扫描转换算法,贴出来分享一下; MFC还不是太明白,主要还是使用OnDraw函数... 大家多指教... void CPolyFillView::OnDraw(CDC* pDC) { CPolyFillDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); // TODO: add draw code for native data here const int POINTNUM=6; //多边形点数. /定义结构体用于活性边表AET和新边表NET/ typedef struct XET { float x; float dx,ymax; XET* next; }AET,NET; /定义点结构体point*/ struct point { float x; float y; }polypoint[POINTNUM]={250,50,550,150,550,400,250,250,100,350,100,100};//多边形顶点 //mypoint[POINTNUM]={100,100,200,100,200,200,100,200};//正方形 /计算最高点的y坐标(扫描到此结束)**/ int MaxY=0; int i; for(i=0;i<POINTNUM;i++) if(polypoint.y>MaxY) MaxY=polypoint.y; /*初始化AET表/ AET *pAET=new AET; pAET->next=NULL; /初始化NET表*/ NET *pNET[1024]; for(i=0;i<=MaxY;i++) { pNET=new NET; pNET->next=NULL; } /扫描并建立NET表*/ for(i=0;i<=MaxY;i++) { for(int j=0;j<POINTNUM;j++) if(polypoint[j].y==i) { if(polypoint[(j-1+POINTNUM)%POINTNUM].y>polypoint[j].y) { NET *p=new NET; p->x=polypoint[j].x; p->ymax=polypoint[(j-1+POINTNUM)%POINTNUM].y; p->dx=(polypoint[(j-1+POINTNUM)%POINTNUM].x-polypoint[j].x)/(polypoint[(j-1+POINTNUM)%POINTNUM].y-polypoint[j].y); p->next=pNET->next; pNET->next=p; } if(polypoint[(j+1+POINTNUM)%POINTNUM].y>polypoint[j].y) { NET *p=new NET; p->x=polypoint[j].x; p->ymax=polypoint[(j+1+POINTNUM)%POINTNUM].y; p->dx=(polypoint[(j+1+POINTNUM)%POINTNUM].x-polypoint[j].x)/(polypoint[(j+1+POINTNUM)%POINTNUM].y-polypoint[j].y); p->next=pNET->next; pNET->next=p; } } } /建立并更新活性边表AET/ for(i=0;i<=MaxY;i++) { //计算新的交点x,更新AET/ NET *p=pAET->next; while(p) { p->x=p->x + p->dx; p=p->next; } //更新后新AET先排序 |
| 1楼:东山山人(2011-06-14 13:20) |
技术贴~支持~ |
| 2楼:dsdzkj(2011-06-14 16:37) |
这个真是技术贴 |