#include "windows.h"
#include <gl\glut.h>

#define sunRaduis 0.4
#define earthRaduis 0.06
#define moonRaduis 0.016

GLfloat rotationSpeed = 0.1;
GLfloat daysInYear = 365;
GLfloat year = 0.0; //degrees
GLfloat day = 0.0;
GLfloat moonAroundEarth = 0.0;
GLfloat moonItsSelf = 0.0;
GLfloat earthOrbitRadius = 1.0;
GLfloat moonOrbitRadius = 0.1;
GLfloat moonAroundEarthRate = 2 * rotationSpeed;
GLfloat moonRotationItselfRate = 5.0 * rotationSpeed;
GLfloat dayRate = 5.0 * rotationSpeed;
GLfloat yearRate = daysInYear / 360.0 * dayRate * rotationSpeed;
void drawSolarSystem(void);
void Initialization(void);
void displayFunc(void);
void reshapeFunc(int x, int y);
void idleFunc(void);
int main(int argc, char* argv[])
{

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(700,700);
    glutCreateWindow("Sonyachna systema");
    Initialization();
    glutReshapeFunc(reshapeFunc);
    glutDisplayFunc(displayFunc);
    glutIdleFunc(idleFunc);
    glutMainLoop();
    return 0;
}
void drawSolarSystem(void)
{

    glPushMatrix();

        gluLookAt(    0.0,0.0,-4.0,
                    0.0,0.0,1.0,
                    0.0,-3.0,0.0);
        glColor3f(1.0,0.8,0.3);
        glutSolidSphere(sunRaduis,50,50);
        glPushMatrix();

            glRotatef(year,0.0,1.0,0.0);
            glTranslatef(earthOrbitRadius,0.0,0.0);
            glRotatef(-year,0.0,1.0,0.0);
            glPushMatrix();
                glRotatef(day,0.25,1.0,0.0);
                glColor3f(0.4,0.6,0.3);
                glutSolidSphere(earthRaduis,10,10);

            glPopMatrix();
            glRotatef(moonAroundEarth,0.0,1.0,0.0);
            glTranslatef(moonOrbitRadius,0.0,0.0);

            glRotatef(-moonAroundEarth,0.0,1.0,0.0);
            glRotatef(moonItsSelf,0.0,1.0,0.0);

            glColor3f(0.3,0.3,0.5);
            glutSolidSphere(moonRaduis,8,8);
        glPopMatrix();

    glPopMatrix();
}

void Initialization(void)
{
    glClearColor(0.0,0.0,0.0,0.0);
    glClearDepth(10.0);



    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void displayFunc(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    drawSolarSystem();
    glFlush();
    glutSwapBuffers();
}

void reshapeFunc(int x, int y)
{
    if (y == 0 || x==0) return;

    glLoadIdentity();
    gluPerspective(40.0,(GLdouble)x/(GLdouble)y,0.5,20.0);
    glMatrixMode(GL_MODELVIEW);
    glViewport(0,0,x,y);
    displayFunc();
}

void idleFunc(void)
{
    day += dayRate;
    year += yearRate;
    moonItsSelf += moonRotationItselfRate;
    moonAroundEarth += moonAroundEarthRate;
    displayFunc();
}