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


#define TRUE 1
#define FALSE 0





typedef struct vec3
{
  float x;
  float y;
  float z;
} vec3;




float ball_1_radius = 5.0f;
float ball_2_radius = 4.0f;
float ball_time = 0;
vec3 ball_pos;





void init(void)
{
  glShadeModel(GL_SMOOTH);
  glClearColor(0.2f, 0.2f, 0.4f, 0.5f);				
  glClearDepth(1.0f);
  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LEQUAL);
  glEnable(GL_COLOR_MATERIAL);
  glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  GLfloat lightPos[4] = {-1.0,1.0,0.5,0.0};
  glLightfv(GL_LIGHT0,GL_POSITION,(GLfloat *) &lightPos);
  glEnable(GL_LIGHT1);
  GLfloat lightAmbient1[4] = {0.0,0.0,0.0,0.0};
  GLfloat lightPos1[4] = {1.0,0.0,-0.2,0.0};
  GLfloat lightDiffuse1[4] = {0.5,0.5,0.3,0.0};
  glLightfv(GL_LIGHT1,GL_POSITION,(GLfloat *) &lightPos1);
  glLightfv(GL_LIGHT1,GL_AMBIENT,(GLfloat *) &lightAmbient1);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,(GLfloat *) &lightDiffuse1);
  glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
}





void display(void)
{
  ball_time++;
  ball_pos.x = cos(ball_time / 50.0) * 5.0f;
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLoadIdentity();
  glDisable(GL_LIGHTING);
  glBegin(GL_POLYGON);
  glColor3f (0.8f, 0.8f, 1.0f);
  glVertex3f (-200.0f, -100.0f, -100.0f);
  glVertex3f (200.0f, -100.0f, -100.0f);
  glColor3f (0.4f, 0.4f, 0.8f);	
  glVertex3f (200.0f, 100.0f, -100.0f);
  glVertex3f (-200.0f, 100.0f, -100.0f);
  glEnd();
  glEnable (GL_LIGHTING);
  glTranslatef (0.0f, 6.0f, -25.0f);
  glPushMatrix();
  glTranslatef (ball_pos.x, ball_pos.y, ball_pos.z);
  glColor3f (1.0f, 1.0f, 0.0f);
  glutSolidSphere (ball_1_radius, 50, 50);
  glPopMatrix();
  glPushMatrix();
  glTranslatef (7.0f, -8.0f, 0.0f);
  glColor3f (1.0f, 1.0f, 0.0f);
  glutSolidSphere (ball_2_radius, 50, 50);
  glPopMatrix();
  glutSwapBuffers();
  glutPostRedisplay();
}






void reshape(int w, int h)  
{
  glViewport (0, 0, w, h);
  glMatrixMode(GL_PROJECTION); 
  glLoadIdentity();  
  if (h == 0)  
  {
    gluPerspective (80, (float) w, 1.0, 5000.0);
  }
  else
  {
    gluPerspective (80, (float)w / (float)h, 1.0, 5000.0);
  }
  glMatrixMode(GL_MODELVIEW);  
  glLoadIdentity(); 
}





void keyboard( unsigned char key, int x, int y ) 
{
  switch (key) 
  {
    case 27:    
      exit (0);
    break;  
    default: 
    break;
  }
}





void arrow_keys( int a_keys, int x, int y ) 
{
  switch(a_keys) 
  {
    case GLUT_KEY_UP:
      glutFullScreen();
    break;
    case GLUT_KEY_DOWN: 
    break;
    default:
    break;
  }
}





int main (int argc, char *argv[]) 
{
  ball_pos.x = 5.0f;
  ball_pos.y = -8.0f;
  ball_pos.z = 0.0f;
  glutInit (&argc, argv);
  glutInitDisplayMode (GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); 
  glutInitWindowSize (1280, 720 ); 
  glutCreateWindow ("Marching cubes" );
  init();
  glutDisplayFunc (display);  
  glutReshapeFunc (reshape);
  glutKeyboardFunc (keyboard);
  glutSpecialFunc (arrow_keys);
  glutMainLoop();
}