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

#define NURP 16

GLfloat ctl[NURP][NURP][3];
GLfloat speed[NURP][NURP];
int up[NURP][NURP];
int showPoints = 0;

GLUnurbsObj *theNurb;

void init_surface(void)
{
    int u, v;
    for (u = 0; u < NURP; u++) {
        for (v = 0; v < NURP; v++) {
                ctl[u][v][0] = 2.0*((GLfloat)u - 1.5);
                ctl[u][v][1] = 2.0*((GLfloat)v - 1.5);
             ctl[u][v][2] = 2.0;
             up[u][v] = 0;
        }
    }
        for(u = 0; u < NURP; u++) 
            speed[0][u] =1;

}

/*  Initialize material property and depth buffer.
 */
void myinit(void)
{
    GLfloat mat_diffuse[] = { 0.7, 0.7, 0.7, 1.0 };
    GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat mat_shininess[] = { 100.0 };

    glClearColor (0.0, 0.0, 0.0, 1.0);
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
    glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);

    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glDepthFunc(GL_LESS);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_AUTO_NORMAL);
    glEnable(GL_NORMALIZE);

    init_surface();

    theNurb = gluNewNurbsRenderer();
    gluNurbsProperty(theNurb, GLU_SAMPLING_TOLERANCE, 25.0);
    gluNurbsProperty(theNurb, GLU_DISPLAY_MODE, GLU_FILL);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glTranslatef (0.0, 0.0, -5.0);
}


GLfloat knots[NURP*2] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 
        1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0};
void display(void)
{
    int i, j;

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glPushMatrix();
    glTranslatef(0.0, 0.0, -3.0);
    glRotatef(330.0, 1.,0.,0.);
    glScalef (0.10, 0.10, 0.10);

    gluBeginSurface(theNurb);
    gluNurbsSurface(theNurb,
        NURP*2, knots,
        NURP*2, knots,
        NURP * 3,
        3,
        &ctl[0][0][0],
        NURP, NURP,
        GL_MAP2_VERTEX_3);
    gluEndSurface(theNurb);

    glPopMatrix();
    glutSwapBuffers();
}

void reshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective (45.0, (GLdouble)w/(GLdouble)h, 3.0, 80.0);

    glMatrixMode(GL_MODELVIEW);
}

void
menu(int value)
{
    switch (value) {
    case 0:
        gluNurbsProperty(theNurb, GLU_DISPLAY_MODE, GLU_FILL);
    break;
    case 1:
        gluNurbsProperty(theNurb, GLU_DISPLAY_MODE, GLU_OUTLINE_POLYGON);
    break;
    }
    glutPostRedisplay();
}

int down = 0, lastx;

int flagmov[4] = {0, 0, 0, 0};
float zeta = 0.9;

void
motion(int x, int y)
{
    if (down) {
        glRotatef(lastx - x, 0, 1, 0);
        lastx = x;
        glutPostRedisplay();
    }
}

int num;
int movup = 0;
void idle(void) {
    int i, j;
        
    num += (movup)?1:-1;
    movup = num < -10 || num > 10 ? !movup : movup;
    for(i = 0; i < NURP; i++) 
        for(j = 0; j < NURP; j++) 
            ctl[i][j][2] = (int)(num*sin((double)i+1));
    glutPostRedisplay();
}

void
mouse(int button, int state, int x, int y)
{
    if (button == GLUT_LEFT_BUTTON) {
        if (state == GLUT_DOWN) {
            lastx = x;
            down = 1;
        } else {
            down = 0;
        }
    }
}

static void
key(unsigned char k, int x, int y)
{
  switch (k) {
  case 27:  /* Escape */
    exit(0);
    break;
  default:
    return;
  }
  glutPostRedisplay();
}

/* Main Loop */
int
main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGB);
    glutCreateWindow(argv[0]);
    myinit();
    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutCreateMenu(menu);
    glutAddMenuEntry("Solid", 0);
    glutAddMenuEntry("Wireframe", 1);
    glutAttachMenu(GLUT_RIGHT_BUTTON);
    glutMouseFunc(mouse);
    glutMotionFunc(motion);
    glutKeyboardFunc(key);
    glutIdleFunc(idle);
    glutMainLoop();
    return 0;             
}