OpenGL实现边缘填充算法

边缘填充的思想：枚举每一条边，对这条边右边的像素进行求补操作，就是有填充则去掉，无填充就进行填充

#include <GL/gl.h>
#include <GL/glut.h>
#include <iostream>
#include <cmath>
#include <cstring>
#include <string>
using namespace std;
int x[]= {10,70,70,60,40,30,20};
int y[]= {10,10,50,40,60,20,30};
int vis[500][500]; //判断该坐标的点是否存在
void init()
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glMatrixMode (GL_PROJECTION);
gluOrtho2D (0.0, 200.0, 0.0, 150.0);
}
void MidBresenhamCircle()
{
memset(vis,0,sizeof(vis));
glClear(GL_COLOR_BUFFER_BIT);
glLineWidth(2);
glBegin(GL_LINES); //绘制多边形形状
for(int i=0; i<7; ++i)
{
glVertex2i(x[i],y[i]);
glVertex2i(x[(i+1)%7],y[(i+1)%7]);
}
glEnd();
glFlush();
glPointSize(2);
glBegin(GL_POINTS);
for(int i=x[1],j=y[1]; i<300; ++i) //特殊处理k=0的边
{
if(!vis[i][j])
{
glColor3f(0.0f,1.0f,0.0f);
glVertex2i(i,j);
vis[i][j]=1;
}
else
{
glColor3f(0.0f,0.0f,0.0f);
glVertex2i(i,j);
vis[i][j]=1;
}
}
for(int j=y[1]; j<=y[2]; ++j) //特殊处理k不存在的边
{
for(int i=x[1]; i<300; ++i)
{
if(!vis[i][j])
{
glColor3f(0.0f,1.0f,0.0f);
glVertex2i(i,j);
vis[i][j]=1;
}
else
{
glColor3f(0.0f,0.0f,0.0f);
glVertex2i(i,j);
vis[i][j]=1;
}
}
}
for(int p=2; p<7; ++p)
{
int k=(y[(p+1)%7]-y
)/(x[(p+1)%7]-x[p]); //求出斜率
int x1=x[(p+1)%7],x0=x[p],y1=y[(p+1)%7],y0=y[p]; //根据斜率推导出这条直线的各个点
if(y1<y0)
{
swap(x1,x0);
swap(y1,y0);
}
for(int j=y0; j<=y1; ++j)
{
int i=(j-y0+k*x0)/k;
for(int px=i; px<300; ++px)
{
if(!vis[px][j])
{
glColor3f(0.0f,1.0f,0.0f);
glVertex2i(px,j);
vis[px][j]=1;
}
else
{
glColor3f(0.0f,0.0f,0.0f);
glVertex2i(px,j);
vis[px][j]=0;
}
}
}
}
glEnd();
glFlush();
}
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
glutInitWindowPosition(100, 100);
glutInitWindowSize(500, 500);
glutCreateWindow("第一个opengl程序");
init();
glutDisplayFunc(MidBresenhamCircle);
glutMainLoop();
return 0;
}

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