图形学算法设计和流程图ppt课件.ppt
DDA算法设计A、数据结构设计函数定义：DDA算法函数：void CTestView:DDALine(int xa,int ya,int xb,int yb)方法调用函数：void CTestView :OnDDALineFunc1()鼠标响应函数：void CTestView :OnDDALineMouse1()鼠标按下事件：void CTestView :OnLButtonDown(UINT nFlags, CPoint point) 鼠标抬起事件：void CTestView :OnLButtonUp(UINT nFlags, CPoint point)B、核心算法设计DDA算法：设直线起点（x0,y0），终点(x1,y1)，k为直线斜率，因有直线公式为y=kx+b，则有斜率k=（y1-y0）/(x1-x0)；当|k|=1时，y坐标：yi+1=yi+1，x坐标：xi+1=xi+1/k；当|k|1时，y坐标：yi+1=yi+k，x坐标：xi+1=xi+1。DDA算法（1）输入DDA算法（2）处理DDA算法（3）输出DDA算法void CTestView:OnDDALineFunc1()/调用DDALine函数CTestView:DDALine(50,50,150,200);/起点（50,50），终点（150,200）void CTestView:OnDDALineMouse1() /鼠标响应调用DDALine函数flag=5;void CTestView:OnLButtonDown(UINT nFlags, CPoint point) /鼠标按下事件bx=point.x; /获取鼠标按下时的横坐标by=point.y; /获取鼠标按下时的横坐标CView:OnLButtonDown(nFlags, point);void CTestView:OnLButtonUp(UINT nFlags, CPoint point)/鼠标抬起事件CClientDC dc(this);if(flag=5)CTestView:DDALine(bx,by,point.x,point.y); /鼠标响应调用DDALine函数CView:OnLButtonUp(nFlags, point);DDA算法void CTestView:DDALine(int xa,int ya,int xb,int yb) /DDALine函数算法CClientDC dc(this);float x,y,k,dx,dy,temp;if(xa=xb)/当xa=xb时，k=0，直线垂直于y轴for(y=ya;yxb) if(xaxb)/确保直线从左向右画temp=xa;xa=xb;xb=temp;temp=ya;ya=yb;yb=temp;y=ya;for(x=xa;x=1)/判断k的绝对值，|k|=1时执行if(yayb)/确保直线从左向右画temp=xa;xa=xb;xb=temp;temp=ya;ya=yb;yb=temp;x=xa;for(y=ya;y0的M点在圆外，d=0时，d更新为d+2x+3，(x,y)更新为(x+1,y)；当d0时，d更新为d+2*(x-y)+5，(x,y)更新为(x+1,y+1)。 当xy时，重复计算绘制点。中点画圆算法-流程图中点画圆算法-1void CTestView :midpointcircle(int xa,int ya,int xb,int yb)CClientDC dc(this);int fzbj=(xb-xa)*(xb-xa)+(yb-ya)*(yb-ya);int r=int(sqrt(double)fzbj),c=0;int x,y;float d;x=0;y=r;d=1.25-r;dc.SetPixel(xa+x,ya+y,c);dc.SetPixel(xa-x,ya+y,c);dc.SetPixel(xa+x,ya-y,c);dc.SetPixel(xa-x,ya-y,c);dc.SetPixel(xa+y,ya+x,c);dc.SetPixel(xa-y,ya+x,c);dc.SetPixel(xa+y,ya-x,c);dc.SetPixel(xa-y,ya+x,c);中点画圆算法-2while(x=y)if(d0) d+=2*x+3;else d+=2*(x-y)+5;y-;x+;dc.SetPixel(xa+x,ya+y,c);dc.SetPixel(xa-x,ya+y,c);dc.SetPixel(xa+x,ya-y,c);dc.SetPixel(xa-x,ya-y,c);dc.SetPixel(xa+y,ya+x,c);dc.SetPixel(xa-y,ya+x,c);dc.SetPixel(xa+y,ya-x,c);dc.SetPixel(xa-y,ya-x,c);void CTestView :Onzero1()flag=6;void CTestView :Onanypoint1()flag=7;中点画圆算法-3void CTestView :OnLButtonDown(UINT nFlags, CPoint point)bx=point.x;by=point.y;CView:OnLButtonDown(nFlags, point);void CTestView :OnLButtonUp(UINT nFlags, CPoint point)CClientDC dc(this);else if(flag=6) CTestView :midpointcircle(0,0,point.x,point.y);else if(flag=7) CTestView :midpointcircle(bx,by,point.x,point.y);CView:OnLButtonUp(nFlags, point);二维图形裁剪-线段裁剪计算点的code值流程图 二维图形裁剪-线段裁剪计算直线与边界交点流程图 二维图形裁剪-线段裁剪算法流程图1 二维图形裁剪-线段裁剪算法流程图2二维图形裁剪-线段裁剪算法流程图总总二维图形裁剪-1void CTestView :OnCohenSutherland1() flag=8;CClientDC dc(this);/边框dc.MoveTo(200,100); /LEFTdc.LineTo(200,400);dc.MoveTo(500,100); /RIGHTdc.LineTo(500,400);dc.MoveTo(200,100);/TOPdc.LineTo(500,100);dc.MoveTo(200,400); /BOTTONdc.LineTo(500,400);void CTestView :OnLButtonDown(UINT nFlags, CPoint point) bx=point.x;by=point.y;CView:OnLButtonDown(nFlags, point);二维图形裁剪-1void CTestView :OnLButtonUp(UINT nFlags, CPoint point) CClientDC dc(this);if(flag=8)dc.MoveTo(bx,by);dc.LineTo(point.x,point.y);ClipLine(bx,by,point.x,point.y);CView:OnLButtonUp(nFlags, point); int CTestView :encode(float x,float y)int c;c=0;if(xXR)c=c|RIGHT;if(yYB)c=c|BOTTOM;else if(yYT)c=c|TOP;return c;二维图形裁剪-2void CTestView :ClipLine(float x1,float y1,float x2,float y2)CClientDC dc(this);float x,y;int code,code1,code2;code1=encode(x1,y1);code2=encode(x2,y2);while(code1!=0 |code2!=0) if(code1&code2)!=0) return; code = code1;if(code1=0)code = code2;二维图形裁剪-3/当直线和左边界有交点if(LEFT&code)!=0)x=XL;y=y1+(y2-y1)*(XL-x1)/(x2-x1);/当直线和右边界有交点else if(RIGHT&code)!=0) x=XR;y=y1+(y2-y1)*(XR-x1)/(x2-x1);/当直线和底边界有交点else if(BOTTOM&code)!=0)y=YB;x=x1+(x2-x1)*(YB-y1)/(y2-y1); /当直线与上边界有交点else if(TOP & code)!=0)y=YT;x=x1+(x2-x1)*(YT-y1)/(y2-y1);二维图形裁剪-4 if(code=code1)x1=x;y1=y;code1 =encode(x,y); elsex2=x;y2=y;code2 =encode(x,y);CPen pen,*old;pen.CreatePen(0,2,RGB(255,0,0);old=dc.SelectObject(&pen);dc.MoveTo(x1,y1);dc.LineTo(x2,y2);dc.SelectObject(old);
