Opengl,C++ : Flood-Fill Algorithm Using Recursion

  #include <GL/glut.h>   
  int ww = 600, wh = 500;   
  float bgCol[3] = {0.2, 0.4,0.0};   
  float intCol[3] = {1.0,0.0,0.0};   
  float fillCol[3] = {0.4,0.0,0.0};   
      void setPixel(int pointx, int pointy, float f[3])   
      {   
             glBegin(GL_POINTS);   
                  glColor3fv(f);   
                  glVertex2i(pointx,pointy);   
             glEnd();   
             glFlush();   
      }   
      void getPixel(int x, int y, float pixels[3])   
      {   
           glReadPixels(x,y,1.0,1.0,GL_RGB,GL_FLOAT,pixels);   
      }   
      void drawPolygon(int x1, int y1, int x2, int y2)   
       {      
             glColor3f(1.0, 0.0, 0.0);   
             glBegin(GL_POLYGON);   
                     glVertex2i(x1, y1);    
                  glVertex2i(x1, y2);   
                  glVertex2i(x2, y2);   
                     glVertex2i(x2, y1);   
             glEnd();   
             glFlush();   
       }   
       void display()   
       {   
             glClearColor(0.2, 0.4,0.0, 1.0);   
             glClear(GL_COLOR_BUFFER_BIT);   
             drawPolygon(150,250,200,300);   
             glFlush();   
       }   
       void floodfill4(int x,int y,float oldcolor[3],float newcolor[3])   
       {   
            float color[3];   
            getPixel(x,y,color);   
            if(color[0]==oldcolor[0] && (color[1])==oldcolor[1] && (color[2])==oldcolor[2])   
            {   
                     setPixel(x,y,newcolor);   
                     floodfill4(x+1,y,oldcolor,newcolor);   
                     floodfill4(x-1,y,oldcolor,newcolor);   
                  floodfill4(x,y+1,oldcolor,newcolor);   
                  floodfill4(x,y-1,oldcolor,newcolor);   
             }   
       }   
       void mouse(int btn, int state, int x, int y)   
       {   
             if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN)    
            {   
                     int xi = x;   
                     int yi = (wh-y);   
                     floodfill4(xi,yi,intCol,fillCol);   
             }   
       }   
       void myinit()   
       {      
            glViewport(0,0,ww,wh);   
            glMatrixMode(GL_PROJECTION);   
            glLoadIdentity();   
            gluOrtho2D(0.0,(GLdouble)ww,0.0,(GLdouble)wh);   
            glMatrixMode(GL_MODELVIEW);   
       }   
       int main(int argc, char** argv)   
       {   
             glutInit(&argc,argv);   
             glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);   
             glutInitWindowSize(ww,wh);   
             glutCreateWindow("Flood-Fill-Recursive");   
             glutDisplayFunc(display);   
             myinit();   
             glutMouseFunc(mouse);   
             glutMainLoop();   
             return 0;   
       }