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

void init()
{
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glOrtho(-15,15,-15,15,-15,5);
}
void circle(GLfloat rx,GLfloat ry,GLfloat x,GLfloat y)//radius_x,radius_y,certre_position_x,centre_position_y
{
    int i=0;
    float angle;
    GLfloat PI = 2.0f * 3.1416;
    glBegin(GL_TRIANGLE_FAN);
    glVertex2f(x,y);
    for(i=0;i<100;i++)
    {
        angle = 2 * PI * i /100;
        glVertex2f(x+(cos(angle)*rx),y+(sin(angle)*ry));
    }
    glEnd();
}


void myDisplay()
{
    glClear(GL_COLOR_BUFFER_BIT);
    
    glColor3f(1.0f, 0.0f, 0.0f);
    circle(3,3,0,0);
    glFlush();
}
int main()
{
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(600, 600);
    glutInitWindowPosition(200, 200);
    glutCreateWindow("Demo Application");
    init();
    glutDisplayFunc(myDisplay);
    glutMainLoop();
    return 0;
}