#include <iostream>
#include <glut.h>

float angle = 0.0f;

float red = 1.0f, blue = 1.0f, green = 1.0f;

float zoom_in_out = 45.0f;
float change_angle_up = 0.0;

void renderScene(void);
void changeSize(int width, int height);
void processSpecialKeys(int key, int x, int y);

int main(int argc, char **argv)
{
    // initialize glut and create window
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowPosition(100, 100);
    glutInitWindowSize(320, 320);
    glutCreateWindow("Solar System");

    // register callback functions
    glutDisplayFunc(renderScene);
    glutReshapeFunc(changeSize);
    glutIdleFunc(renderScene);


    // register keyboard entry
    glutSpecialFunc(processSpecialKeys);

    // enter glut event processing loop
    glutMainLoop();

    return 1;
}

void renderScene(void)
{
    // clear color and depth buffers
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // reset transformations
    glLoadIdentity();

    // set camera
    gluLookAt(50.0f, 50.0f, zoom_in_out,
              0.0f, 0.0f, 0.0f,
              0.5f, 0.5f, 0.5f);

    // draw earth
    glPushMatrix();
        glColor3f(0.5, 1, 0.5);
        glRotatef(angle, 0.0f, 1.0f, 0.0f);
        glTranslatef(0.0f, 0.0f, 50.0f);
        glPushMatrix();
            glColor3f(1, 1,1);
            glRotatef(angle, 0.0f, 0.0f, 1.0f);
            glTranslatef(0.1f,0.1f,0.0f);
            glutSolidSphere(5, 50, 50);
        glPopMatrix();
        glutSolidSphere(5, 50, 50);
    glPopMatrix();

    // draw sun
    glPushMatrix();
        glColor3f(1.0f, 1.0f, 0.0f);
        glTranslatef(0.0f, 0.0f, 0.0f);
        glutSolidSphere(10, 50, 50);
    glPopMatrix();



    //rotate
    angle += 0.1f;

    glutSwapBuffers();
}

void changeSize(int width, int height)
{

    // prevent division by zero when window is too short
    if (height == 0) height = 1;
    float ratio = 1.0* width / height;

    // use the projection matrix
    glMatrixMode(GL_PROJECTION);

    // reset matrix
    glLoadIdentity();

    // set the viewport to be the entire window
    glViewport(0, 0, width, height);

    // set the correct perspective
    gluPerspective(45, ratio, 1, 1000);

    // Get Back to the Modelview
    glMatrixMode(GL_MODELVIEW);
}

void processSpecialKeys(int key, int x, int y)
{
    switch (key)
    {
    case GLUT_KEY_LEFT:
        break;
    case GLUT_KEY_RIGHT:
        break;
    case GLUT_KEY_UP:
        //if(zoom_in_out != 30.0f)
        zoom_in_out -= 3.0f;
        break;
    case GLUT_KEY_DOWN:
        //if (zoom_in_out != 60.0f)
        zoom_in_out += 3.0f;
        break;
    }
}