/*  light2.c
 
    This program creates an animation of a green teapot, and uses the
    function glutIdleFunc() to choose between two different modes in
    the animation, one that causes the display to spin and one that
    does nothing (NULL)
*/

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

static GLfloat spin = 0.0;
GLint toggle = 0;

static GLfloat light0_position[] = {2.0, 8.0, 2.0, 0.0};
GLfloat mat_specular[]         = {1.0, 1.0, 1.0, 1.0};
GLfloat mat_shininess[]        = {50.0};
GLfloat mat_amb_diff_color[]     = {0.5, 0.7, 0.5, 0.5};
GLfloat light_diffuse[] = {1.0, 1.0, 1.0, 1.0};
GLfloat light_ambient[] = {0.15, 0.15, 0.15};
GLfloat light_specular[] = {1.0, 1.0, 1.0, 1.0};

void init () {
  glClearColor(1.0, 1.0, 1.0, 1.0);
  glShadeModel(GL_SMOOTH);   
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);  
}

void display (void)
{ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
  glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
  glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient); 
  glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
  glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, mat_amb_diff_color);
  glLoadIdentity();
  gluLookAt(2.0, 4.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
  glPushMatrix();
  glScalef(2.0, 2.0, 2.0);
  glRotatef(spin, 0.0, 1.0, 0.0);
  glutSolidTeapot(1.0);
  glPopMatrix();
  glutSwapBuffers();
}



void reshape(int w, int h)
{
  glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  glMatrixMode (GL_PROJECTION);	
  glLoadIdentity ();	/*  define the projection  */
  gluPerspective(45.0, (GLfloat) w / (GLfloat) h, 1.0, 20.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

void spinDisplay()
{ spin += 5.0;
  if (spin >360.0) 
    spin = spin - 360.0;
  glutPostRedisplay();
}

void mouse(int button, int state, int x, int y) 
{
  switch (button) {
     case GLUT_LEFT_BUTTON:
        if (state == GLUT_DOWN)
           glutIdleFunc(spinDisplay);
        break;
     case GLUT_MIDDLE_BUTTON:
     case GLUT_RIGHT_BUTTON:
        if (state == GLUT_DOWN)
           glutIdleFunc(NULL);
        break;
     default:
        break;
   }
}

int main(int argc, char** argv)
{
  glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  glutInitWindowPosition (0, 0);
  glutInitWindowSize(400, 400);
  glutCreateWindow ("Scaling Transformation");
  init ();
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutMouseFunc(mouse);
  glutMainLoop();
  return 0;
    
}