#include <GL/openglut.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef GL_VERSION_1_1
GLuint list;
GLint fill = 1;
GLfloat spinx = 0;
GLfloat spiny = 0;
GLfloat tdist = 0.0;
GLfloat polyfactor = 1.0;
GLfloat polyunits = 1.0;
GLboolean doubleBuffer;
void display (void)
{
    GLfloat gray[] = { 0.8, 0.8, 0.8, 1.0 };
    GLfloat black[] = { 0.0, 0.0, 0.0, 1.0 };
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix ();
    glTranslatef (0.0, 0.0, tdist);
    glRotatef ((GLfloat) spinx, 1.0, 0.0, 0.0);
    glRotatef ((GLfloat) spiny, 0.0, 1.0, 0.0);
    glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, gray);
    glMaterialfv(GL_FRONT, GL_SPECULAR, black);
    glMaterialf(GL_FRONT, GL_SHININESS, 0.0);
    if (fill) { 
       glEnable(GL_LIGHTING);
       glEnable(GL_LIGHT0);
       glEnable(GL_POLYGON_OFFSET_FILL);
       glPolygonOffset(polyfactor, polyunits);
       glCallList (list);
       glDisable(GL_POLYGON_OFFSET_FILL);
    }
    glDisable(GL_LIGHTING);
    glDisable(GL_LIGHT0);
    glColor3f (1.0, 1.0, 1.0);
    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
    glPolygonOffset(-polyfactor, -polyunits);
    if (!fill) glEnable(GL_POLYGON_OFFSET_LINE); 
    glCallList (list);
    glDisable(GL_POLYGON_OFFSET_LINE);
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    if (!fill) { 
       glEnable(GL_LIGHTING);
       glEnable(GL_LIGHT0);
       glCallList (list);
    }
    glPopMatrix ();
    glFlush ();
    if (doubleBuffer) glutSwapBuffers();
}
void gfxinit (void)
{
    GLfloat light_ambient[] = { 0.0, 0.0, 0.0, 1.0 };
    GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat light_specular[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 };
    GLfloat global_ambient[] = { 0.2, 0.2, 0.2, 1.0 };
    glClearColor (0.0, 0.0, 0.0, 1.0);
    list = glGenLists(1);
    glNewList (list, GL_COMPILE);
       glutSolidSphere(1.0, 20, 12);
    glEndList ();
    glEnable(GL_DEPTH_TEST);
    glLightfv (GL_LIGHT0, GL_AMBIENT, light_ambient);
    glLightfv (GL_LIGHT0, GL_DIFFUSE, light_diffuse);
    glLightfv (GL_LIGHT0, GL_SPECULAR, light_specular);
    glLightfv (GL_LIGHT0, GL_POSITION, light_position);
    glLightModelfv (GL_LIGHT_MODEL_AMBIENT, global_ambient);
}
void reshape(int width, int height)
{
    glViewport (0, 0, width, height);
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    gluPerspective(45.0, (GLdouble)width/(GLdouble)height,
        1.0, 10.0);
    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();
    gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
}
static void Benchmark( float xdiff, float ydiff )
{
   int startTime, endTime;
   int draws;
   double seconds, fps;
   printf("Benchmarking...\n");
   draws = 0;
   startTime = glutGet(GLUT_ELAPSED_TIME);
   spinx = spiny = 0.0;
   do {
      spinx += xdiff;
      spiny += ydiff;
      display();
      draws++;
      endTime = glutGet(GLUT_ELAPSED_TIME);
   } while (endTime - startTime < 5000);   
   
   seconds = (double) (endTime - startTime) / 1000.0;
   fps = draws / seconds;
   printf("Result:  fps: %g\n", fps);
}
void mouse(int button, int state, int x, int y) {
    switch (button) {
    case GLUT_LEFT_BUTTON:
        switch (state) {
        case GLUT_DOWN:
            spinx += 5;
                    glutPostRedisplay();
            break;
        default:
            break;
            }
            break;
    case GLUT_MIDDLE_BUTTON:
        switch (state) {
        case GLUT_DOWN:
            spiny += 5;
                    glutPostRedisplay();
            break;
        default:
            break;
            }
            break;
    case GLUT_RIGHT_BUTTON:
        switch (state) {
        case GLUT_UP:
            exit(0);
            break;
        default:
            break;
            }
            break;
        default:
            break;
    }
}
void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 't':
         if (tdist < 4.0) {
            tdist = (tdist + 0.5);
            glutPostRedisplay();
         }
         break;
      case 'T':
         if (tdist > -5.0) {
            tdist = (tdist - 0.5);
            glutPostRedisplay();
         }
         break;
      case 'F':
         polyfactor = polyfactor + 0.1;
     printf ("polyfactor is %f\n", polyfactor);
         glutPostRedisplay();
         break;
      case 'f':
         polyfactor = polyfactor - 0.1;
     printf ("polyfactor is %f\n", polyfactor);
         glutPostRedisplay();
         break;
      case 'U':
         polyunits = polyunits + 1.0;
     printf ("polyunits is %f\n", polyunits);
         glutPostRedisplay();
         break;
      case 'u':
         polyunits = polyunits - 1.0;
     printf ("polyunits is %f\n", polyunits);
         glutPostRedisplay();
         break;
      case 'b':
     Benchmark(5.0, 0);
     break;
      case 'B':
     Benchmark(0, 5.0);
     break;
      case ' ':
     fill = !fill;
     printf ("fill/line: %d\n", fill);
         glutPostRedisplay();
         break;
      case 27:  
         exit(0);
         break;
      default:
         break;
   }
}
static void
key(unsigned char k, int x, int y)
{
  switch (k) {
  case 27:  
    exit(0);
    break;
  default:
    return;
  }
  glutPostRedisplay();
}
GLenum Args(int argc, char **argv)
{
    GLint i;
    doubleBuffer = GL_FALSE;
    for (i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-sb") == 0) {
        doubleBuffer = GL_FALSE;
    } else if (strcmp(argv[i], "-db") == 0) {
        doubleBuffer = GL_TRUE;
    } else {
        printf("%s (Bad option).\n", argv[i]);
        return GL_FALSE;
    }
    }
    return GL_TRUE;
}
int main(int argc, char** argv)
{
    GLuint type;
    glutInit(&argc, argv);
    Args(argc, argv);
    type = GLUT_DEPTH | GLUT_RGB;
     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
    glutInitDisplayMode(type);
    glutCreateWindow("polyoff");
    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutMouseFunc(mouse);
    glutKeyboardFunc(keyboard);
    gfxinit();
    glutMainLoop();
    return 0;
}
#else
int main(int argc, char** argv)
{
    fprintf (stderr, "This program demonstrates a feature which is not in OpenGL Version 1.0.\n");
    fprintf (stderr, "If your implementation of OpenGL Version 1.0 has the right extensions,\n");
    fprintf (stderr, "you may be able to modify this program to make it run.\n");
    return 0;
}
#endif