КГ Лаб1 Етиописки

#include <GL/gl.h>
#include <GL/glut.h>
#include <math.h>
#include <stdlib.h>

int n;
float a;
void display();
static void init()
{
  /* set clear color to white */
  glClearColor (1.0, 1.0, 1.0, 0.0);
  /* set fill  color to black */
  glColor3f(0.0, 0.0, 0.0);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  gluOrtho2D(-0.5, 1.5, -0.5, 1.5);

} /* end init */

int main(int argc, char* argv[])
{
    if(argc>1)
        n=atoi(argv[1]);
    else
        n=3;


  glutInit(&argc,argv);
  glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
  glutInitWindowSize(600, 600);
  glutInitWindowPosition(100,100);
  glutCreateWindow(argv[0]);
  glutDisplayFunc(display);
  init();
  glutMainLoop();
  return 0;
}

void display()
{
    glClear (GL_COLOR_BUFFER_BIT);
    void etiop(float, float, float, float, int);
    etiop(0.0,0.0,1.0,0,n);
    glFlush();
}

void etiop(float x1, float y1, float x2, float y2, int n)
{
    float xa,ya,xb,yb,xc,yc,xd,yd,xdg,ydg,xdd,ydd,k,d;
    if(n<=0)
    {
        glBegin(GL_LINES);
            glVertex2f(x1,y1);
      glVertex2f(x2,y2);
      glEnd();
        return;
    }
    else
    {
        xa=x1+(x2-x1)/5;
        ya=y1+(y2-y1)/5;
        xb=x1+(x2-x1)*4/5;
        yb=y1+(y2-y1)*4/5;

        k=atan2(yb-ya,xb-xa);
        d= sqrt (( xb - xa) *(xb - xa)+(yb - ya) *(yb - ya) ) ;
        d = d/sqrt(2);

        xc=xa+d*cos(k+M_PI/4);
        yc=ya+d*sin(k+M_PI/4);
        xd=xa+d*cos(k-M_PI/4);
        yd=ya+d*sin(k-M_PI/4);

        d= sqrt (( xa - x1) *(xa - x1)+(ya - y1) *(ya - y1) ) ;


        k=atan2(yb-ya,xb-xa);
        xdg=xc+d*cos(k+M_PI/2);
        ydg=yc+d*sin(k+M_PI/2);
        xdd=xd+d*cos(k-M_PI/2);
        ydd=yd+d*sin(k-M_PI/2);


        etiop(xc,yc,xdg,ydg,n-1);
        etiop(xd,yd,xdd,ydd,n-1);


        etiop(x1,y1,xa,ya,n-1);
        etiop(xa,ya,xd,yd,n-1);
        etiop(xd,yd,xb,yb,n-1);
        etiop(xa,ya,xc,yc,n-1);
        etiop(xc,yc,xb,yb,n-1);
        etiop(xb,yb,x2,y2,n-1);
    }
}