/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED 
 * Permission to use, copy, modify, and distribute this software for 
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation, and that 
 * the name of Silicon Graphics, Inc. not be used in advertising
 * or publicity pertaining to distribution of the software without specific,
 * written prior permission. 
 *
 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
 * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
 * 
 * US Government Users Restricted Rights 
 * Use, duplication, or disclosure by the Government is subject to
 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
 * clause at DFARS 252.227-7013 and/or in similar or successor
 * clauses in the FAR or the DOD or NASA FAR Supplement.
 * Unpublished-- rights reserved under the copyright laws of the
 * United States.  Contractor/manufacturer is Silicon Graphics,
 * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
 *
 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
 */
/*
 *  surface.c
 *  This program draws a NURBS surface in the shape of a 
 *  symmetrical hill.
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdlib.h>
#include <GL/glaux.h>

GLfloat ctlpoints[4][4][3];

GLUnurbsObj *theNurb;

/*
 *  Initializes the control points of the surface to a small hill.
 *  The control points range from -3 to +3 in x, y, and z
 */
void init_surface(void)
{
  int u, v;

  for (u = 0; u < 4; u++) {
    for (v = 0; v < 4; v++) {
      ctlpoints[u][v][0] = 2.0 * ((GLfloat) u - 1.5);
      ctlpoints[u][v][1] = 2.0 * ((GLfloat) v - 1.5);

      if ((u == 1 || u == 2) && (v == 1 || v == 2))
	ctlpoints[u][v][2] = 3.0;
      else
	ctlpoints[u][v][2] = -3.0;
    }
  }
}

/*
 * 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);
}

void display(void)
{
  GLfloat knots[8] =
  {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0};

  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glPushMatrix();
  glRotatef(330.0, 1., 0., 0.);
  glScalef(0.5, 0.5, 0.5);

  gluBeginSurface(theNurb);
  gluNurbsSurface(theNurb,
		  8, knots,
		  8, knots,
		  4 * 3,
		  3,
		  &ctlpoints[0][0][0],
		  4, 4,
		  GL_MAP2_VERTEX_3);
  gluEndSurface(theNurb);

  glPopMatrix();
  glFlush();
}

void myReshape(int w, int h)
{
  glViewport(0, 0, w, h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(45.0, (GLdouble) w / (GLdouble) h, 3.0, 8.0);

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

/*
 * Main Loop 
 */
int main(int argc, char **argv)
{
  auxInitDisplayMode(AUX_SINGLE | AUX_RGB | AUX_DEPTH);
  auxInitPosition(0, 0, 500, 500);
  if (!auxInitWindow(argv[0]))
    auxQuit();
  myinit();
  auxReshapeFunc(myReshape);
  auxMainLoop(display);
  return 0;
}