Scan Line Fill.cpp

#include<stdio.h>  
#include<GL/glut.h>  
#include<math.h>  
#include <cstdlib>  
int le[500], re[500], flag = 0, m;  
void init()  
{  
gluOrtho2D(0, 500, 0, 500);  
}  
void edge(int x0, int y0, int x1, int y1)  
{  
  if (y1 < y0)  
  {  
  int tmp;  
  tmp = y1;  
  y1 = y0;  
  y0 = tmp;  
  tmp = x1;  
  x1 = x0;  
  x0 = tmp;  
  }  
  int x = x0;  
  m = (y1 - y0) / (x1 - x0);  
  for (int i = y0; i < y1; i++)  
  {  
    if (x < le[i])  
    le[i] = x;  
    if (x > re[i])  
    re[i] = x;  
    x += (1 / m);  
  }  
}  
void display()  
{  
  glClearColor(1, 1, 1, 1);  
  glClear(GL_COLOR_BUFFER_BIT);  
  glColor3f(0.0, 0, 0);  
  glBegin(GL_LINE_LOOP);  
  glVertex2f(200, 100);  
  glVertex2f(100, 200);  
  glVertex2f(200, 300);  
  glVertex2f(300, 200);  
  glEnd();  
  for (int i = 0; i < 500; i++)  
  {  
    le[i] = 500;  
    re[i] = 0; 
  }  
  edge(200, 100, 100, 200);  
  edge(100, 200, 200, 300);  
  edge(200, 300, 300, 200);  
  edge(300, 200, 200, 100);  
  if (flag == 1)  
  {  
    for (int i = 0; i < 500; i++)  
    {  
    if (le[i] < re[i])  
      {  
        for (int j = le[i]; j < re[i]; j++)  
        {  
        glColor3f(1, 0.5, 0.0);  
        glBegin(GL_POINTS);  
        glVertex2f(j, i);  
        glEnd();  
        }  
      } 
    } 
} 
glFlush(); 
} 
void ScanMenu(int id) { 
  if (id == 1) 
  flag = 1; 
  else if (id == 2) 
  flag = 0; 
  else 
  exit(0); 
  glutPostRedisplay(); 
} 
void main(int argc, char **argv)  
{ 
  glutInit(&argc, argv); 
  glutInitWindowPosition(100,100); 
  glutInitWindowSize(500, 500); 
  glutCreateWindow("scan line"); 
  init(); 
  glutDisplayFunc(display); 
  glutCreateMenu(ScanMenu); 
  glutAddMenuEntry("scanfill", 1); 
  glutAddMenuEntry("clear", 2); 
  glutAddMenuEntry("exit", 3); 
  glutAttachMenu(GLUT_RIGHT_BUTTON); 
  glutMainLoop(); 
}