Graphics—边标志算法

#include "stdafx.h"#include <graphics.h>#include <iostream>using namespace std;//边标志算法void edgeMarkFill(int n,int *points){ int flag=0;//标志位，判断在图形区域内(1)，还是在外面(0) int c1=0,c2=0;//c1为边界色，c2为背景色 int maxX=0,minX=0,maxY=0,minY=0; int i=0,j=0;  //求maxX和minX for(i=0,maxX=minX=points[0];i<n*2;i+=2) { if(maxX<points[i]) maxX=points[i]; else minX=points[i]; } //求maxY和minY for(i=1,maxY=minY=points[1];i<n*2;i+=2) { if(maxY<points[i]) maxY=points[i]; else minY=points[i]; }  //下面进行边标志填充 for(i=minY+1;i<maxY;i++) { for(j=minX;j<=maxX;j++) {c1=c2;c2=getpixel(j,i);//getpixel()返回值为该像素点的RGB值if(c1==WHITE&&c2==BLACK)flag=!flag;if(flag)putpixel(j,i,WHITE); }     //为现实效果而延迟时间的空循环 for(int cc=0;cc<10000000;cc++); }}int main(){ int gdriver=DETECT, gmode; initgraph(&gdriver,&gmode,"");//根据测试结果初始化图形界面 int points1[]={50,50,200,100,200,250,100,250,50,80,50,50};//定义多边形点的坐标 drawpoly(6,points1);          //画多边形 edgeMarkFill(6,points1);      //边标志填充 getchar(); closegraph();  return 0;}

运行结果：

/*边界标志算法1. 对多边形的每一条边进行扫描转换，即对多边形边界所经过的象素作一个边界标志。2.填充    对每条与多边形相交的扫描线，按从左到右的顺序，逐个访问该扫描线上的象素。    取一个布尔变量inside来指示当前点的状态，若点在多边形内，则inside为真。若点在多边形外，则inside为假。    Inside 的初始值为假，每当当前访问象素为被打上标志的点，就把inside取反。对未打标志的点，inside不变。*/#include "stdafx.h"#include "math.h"#include "windows.h"#include "stdio.h"#include "conio.h"#include "graphics.h" int maxx,maxy,minx,miny;   //图形的边界void dda(int x1,int y1,int x2,int y2){int steps;    double xin,yin,dx,dy,x,y;    dx = x2 - x1;    dy = y2 - y1;    if(fabs(dx) > fabs(dy))steps = fabs(dx);else        steps = fabs(dy);    xin = (double)(dx/steps);yin = (double)(dy/steps);x = x1;y = y1;    int xfom,yfom;  //保存之前一个的坐标    COLORREF k = RGB(0,0,255);    for(int i = 0;i < steps;i++)    {  xfom = x;        yfom = y;            x = x + xin;          y = y + yin;                  if(yfom != (int)y)putpixel(x,y,k);          if((y == maxy) || (y == miny))putpixel(x,y,RGB(255,255,255));  //处理极值奇点，涂成背景色}putpixel(x1,y1,RGB(255,255,255));   //涂成背景色 putpixel(x2,y2,RGB(255,255,255));   //涂成背景色 }   //填充多边形void filling(){putpixel(maxx,maxy,RGB(255,255,255));  //处理极值奇点，涂成背景色    putpixel(minx,miny,RGB(255,255,255));  //处理极值奇点，涂成背景色    double x1, y1;    int in_flag;  //指示当前点的状态是否在边界内部     for(y1 = miny-1 ; y1 <maxy;y1++)    {         in_flag = 0;//多边形内部标志变量for( x1 = minx-1;x1<maxx;x1++){ COLORREF l,m;            l = getpixel(x1,y1);            m = RGB(0,0,255);//多边形边界颜色            if (l == m){if (in_flag == 0)     in_flag = 1;                elsein_flag = 0;}if (in_flag)putpixel(x1,y1,RGB(0,0,255));//在多边形内部填充色蓝色            else                  putpixel(x1,y1,RGB(255,255,255));             //在多边形外部填充色白色    }}     }   int main(){     int x[100],y[100];        int n;   //代表边的个数    printf("请输入多边形边的个数： ");    scanf("%d",&n);    printf("\n请依次输入多边形每一个点的坐标：\n");    scanf("%d%d",&x[0],&y[0]);    maxx = x[0];     minx = x[0];    maxy = y[0];    miny = y[0];    for(int i = 1;i < n;i ++)    {        scanf("%d%d",&x[i],&y[i]);        if(maxx < x[i])    //图形的边界            maxx = x[i];        if(minx > x[i])            minx = x[i];        if(maxy < y[i])            maxy = y[i];        if(miny > y[i])            miny = y[i];    }         //图形初始化    initgraph(800,800);     //设置蓝背景    setbkcolor(WHITE);    cleardevice();        for(int j = 1;j < n;j ++)        dda(x[j - 1],y[j - 1],x[j],y[j]);    dda(x[0],y[0],x[n-1],y[n-1]);    putpixel(x[0],y[0],RGB(255,255,255));putpixel(x[n-1],y[n-1],RGB(255,255,255));    filling(); //填充多边形     getch();     closegraph();     return 0;}/*100 100700 100700 500600 400400 600300 200200 300*/

运行结果：