/*
 *  colormat.c
 *  After initialization, the program will be in
 *  ColorMaterial mode.  Interaction:  pressing the 
 *  mouse buttons will change the diffuse reflection values.
 */
#include <GL/glut.h>
#include <stdlib.h>

GLfloat diffuseMaterial[4] = { 0.5, 0.5, 0.5, 1.0 };

/*  Initialize material property, light source, lighting model,
 *  and depth buffer.
 */
void init(void) 
{
   GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
   GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 };

   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel (GL_SMOOTH);
   glEnable(GL_DEPTH_TEST);
//Material setup
   glMaterialfv(GL_FRONT, GL_DIFFUSE, diffuseMaterial);
   glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
   glMaterialf(GL_FRONT, GL_SHININESS, 25.0);
//light setup
   glLightfv(GL_LIGHT0, GL_POSITION, light_position);
   glEnable(GL_LIGHTING);
   glEnable(GL_LIGHT0);

   glColorMaterial(GL_FRONT, GL_DIFFUSE);
   glEnable(GL_COLOR_MATERIAL);
}

void display(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glutSolidSphere(1.0, 20, 16);
   glFlush ();
}

void reshape (int w, int h)
{
   glViewport (0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode (GL_PROJECTION);
   glLoadIdentity();
   if (w <= h)
      glOrtho (-1.5, 1.5, -1.5*(GLfloat)h/(GLfloat)w,
         1.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
   else
      glOrtho (-1.5*(GLfloat)w/(GLfloat)h,
         1.5*(GLfloat)w/(GLfloat)h, -1.5, 1.5, -10.0, 10.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

void mouse(int button, int state, int x, int y)
{
   switch (button) {
      case GLUT_LEFT_BUTTON:
         if (state == GLUT_DOWN) {
            diffuseMaterial[0] += 0.1;
            if (diffuseMaterial[0] > 1.0)
               diffuseMaterial[0] = 0.0;
            glColor4fv(diffuseMaterial);
printf("diffuse Material[0] %f \n", diffuseMaterial[0]);
            glutPostRedisplay();
         }
         break;
      case GLUT_MIDDLE_BUTTON:
         if (state == GLUT_DOWN) {
            diffuseMaterial[1] += 0.1;
            if (diffuseMaterial[1] > 1.0)
               diffuseMaterial[1] = 0.0;
            glColor4fv(diffuseMaterial);
printf("diffuse Material[1]%f\n", diffuseMaterial[1]);
            glutPostRedisplay();
         }
         break;
      case GLUT_RIGHT_BUTTON:
         if (state == GLUT_DOWN) {
            diffuseMaterial[2] += 0.1;
            if (diffuseMaterial[2] > 1.0)
               diffuseMaterial[2] = 0.0;
            glColor4fv(diffuseMaterial);
printf("diffuse Material[2]%f \n ", diffuseMaterial[2]);
            glutPostRedisplay();
         }
         break;
      default:
         break;
   }
}

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

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize (500, 500); 
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display); 
   glutReshapeFunc(reshape);
   glutMouseFunc(mouse);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0;
}