Latihan OpenGL (4)

ini adalah soal uts yang saya dapatkan,  terima kasih untuk kawan-kawan yang telah nenbei inspirasi dan dukungan. salam kompak selalu ....

#include "stdlib.h"
#include "gl/glut.h"
#include "math.h"

const double PI = 3.141592653589793;
int i;

void lingkaran(int radius, int jumlah_titik, int x_tengah, int y_tengah) {
 glBegin(GL_POLYGON);
 for (i=0;i<=360;i++){
        float sudut=i*(2*PI/jumlah_titik);
        float x=x_tengah+radius*cos(sudut);
        float y=y_tengah+radius*sin(sudut);
  glVertex2f(x,y);
 }
 glEnd();
}

void back(){
  glBegin(GL_QUADS);
  glColor3f(0.,0.3,0.2);
  glVertex2d (-145,145);
  glVertex2d(145,145);
  glVertex2d(145,-145);
  glVertex2d (-145,-145);
  glEnd(); }


void Draw() {
 glClear(GL_COLOR_BUFFER_BIT);

 int x,y,b;
    glBegin(GL_LINES);
        glColor3f(0.,1.,0.);
        glVertex2f(-150,0);
        glVertex2f(150,0);
    glEnd();

    glBegin(GL_LINES);
        glVertex2f(55,150);
        glVertex2f(55,-150);
    glEnd();

    glBegin(GL_LINES);
        glColor3f(0.,1.,0.);
        glVertex2f(-55,150);
        glVertex2f(-55,-150);
    glEnd();

//==========================================================

x=-55;
y=0;

        for (b=1;b<=2;b++)
        {
       
            glColor3f(0.,1.,0.);
            lingkaran(40,100,x,y);
            x+=110;
        }




//===========================================================
 glFlush();
}

int main(int argc, char **argv) {
 glutInit(&argc, argv);
 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
 glutInitWindowSize(700, 600);
 glutInitWindowPosition(0, 0);
 glutCreateWindow("Basuki 09.10.031.802.046");
 gluOrtho2D(-150., 150., -150., 150.);
 glutDisplayFunc(Draw);
 glutMainLoop();
 return 0;
}