www.pudn.com > openglbk.rar > trim.c

/* 
 * Copyright (c) 1993-1999, 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 * Unpublished-- rights reserved under the copyright laws of the 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(R) is a registered trademark of Silicon Graphics, Inc. 
 */ 
 
/* 
 *  trim.c 
 *  This program draws a NURBS surface in the shape of a  
 *  symmetrical hill, using both a NURBS curve and pwl 
 *  (piecewise linear) curve to trim part of the surface. 
 */ 
#include  
#include  
#include  
 
#ifndef CALLBACK 
#define CALLBACK 
#endif 
 
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; 
      } 
   } 
} 
 
void CALLBACK nurbsError(GLenum errorCode) 
{ 
   const GLubyte *estring; 
 
   estring = gluErrorString(errorCode); 
   fprintf (stderr, "Nurbs Error: %s\n", estring); 
   exit (0); 
} 
			 
/*  Initialize material property and depth buffer. 
 */ 
void init(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, 0.0); 
   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); 
   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); 
   gluNurbsCallback(theNurb, GLU_ERROR,  
                    nurbsError); 
} 
 
void display(void) 
{ 
   GLfloat knots[8] = {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0}; 
   GLfloat edgePt[5][2] = /* counter clockwise */ 
      {{0.0, 0.0}, {1.0, 0.0}, {1.0, 1.0}, {0.0, 1.0}, {0.0, 0.0}}; 
   GLfloat curvePt[4][2] = /* clockwise */  
      {{0.25, 0.5}, {0.25, 0.75}, {0.75, 0.75}, {0.75, 0.5}}; 
   GLfloat curveKnots[8] =  
      {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0}; 
   GLfloat pwlPt[4][2] = /* clockwise */  
      {{0.75, 0.5}, {0.5, 0.25}, {0.25, 0.5}}; 
 
   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); 
   gluBeginTrim (theNurb); 
      gluPwlCurve (theNurb, 5, &edgePt[0][0], 2, GLU_MAP1_TRIM_2); 
   gluEndTrim (theNurb); 
   gluBeginTrim (theNurb); 
      gluNurbsCurve (theNurb, 8, curveKnots, 2,  
                     &curvePt[0][0], 4, GLU_MAP1_TRIM_2); 
      gluPwlCurve (theNurb, 3, &pwlPt[0][0], 2, GLU_MAP1_TRIM_2); 
   gluEndTrim (theNurb); 
   gluEndSurface(theNurb); 
         
   glPopMatrix(); 
   glFlush(); 
} 
 
void reshape(int w, int h) 
{ 
   glViewport(0, 0, (GLsizei) w, (GLsizei) 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); 
} 
 
void keyboard(unsigned char key, int x, int y) 
{ 
   switch (key) { 
      case 27: 
         exit(0); 
         break; 
   } 
} 
 
/*  Main Loop  
 */ 
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(); 
   glutReshapeFunc(reshape); 
   glutDisplayFunc(display); 
   glutKeyboardFunc (keyboard); 
   glutMainLoop(); 
   return 0;  
}