www.pudn.com > openglbk.rar > unproject.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 * Unpublished-- rights reserved under the copyright laws of the 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. 
 */ 
 
/* 
 *  unproject.c 
 *  When the left mouse button is pressed, this program  
 *  reads the mouse position and determines two 3D points  
 *  from which it was transformed.  Very little is displayed. 
 */ 
#include  
#include  
#include  
 
void display(void) 
{ 
   glClear(GL_COLOR_BUFFER_BIT); 
   glFlush(); 
} 
 
/* Change these values for a different transformation  */ 
void reshape(int w, int h) 
{ 
   glViewport (0, 0, (GLsizei) w, (GLsizei) h); 
   glMatrixMode(GL_PROJECTION); 
   glLoadIdentity(); 
   gluPerspective (45.0, (GLfloat) w/(GLfloat) h, 1.0, 100.0); 
   glMatrixMode(GL_MODELVIEW); 
   glLoadIdentity(); 
} 
 
void mouse(int button, int state, int x, int y)  
{ 
   GLint viewport[4]; 
   GLdouble mvmatrix[16], projmatrix[16]; 
   GLint realy;  /*  OpenGL y coordinate position  */ 
   GLdouble wx, wy, wz;  /*  returned world x, y, z coords  */ 
 
   switch (button) { 
      case GLUT_LEFT_BUTTON: 
         if (state == GLUT_DOWN) { 
            glGetIntegerv (GL_VIEWPORT, viewport); 
            glGetDoublev (GL_MODELVIEW_MATRIX, mvmatrix); 
            glGetDoublev (GL_PROJECTION_MATRIX, projmatrix); 
/*  note viewport[3] is height of window in pixels  */ 
            realy = viewport[3] - (GLint) y - 1; 
            printf ("Coordinates at cursor are (%4d, %4d)\n", x, realy); 
            gluUnProject ((GLdouble) x, (GLdouble) realy, 0.0,  
               mvmatrix, projmatrix, viewport, &wx, &wy, &wz);  
            printf ("World coords at z=0.0 are (%f, %f, %f)\n",  
               wx, wy, wz); 
            gluUnProject ((GLdouble) x, (GLdouble) realy, 1.0,  
               mvmatrix, projmatrix, viewport, &wx, &wy, &wz);  
            printf ("World coords at z=1.0 are (%f, %f, %f)\n",  
               wx, wy, wz); 
         } 
         break; 
      case GLUT_RIGHT_BUTTON: 
         if (state == GLUT_DOWN) 
            exit(0); 
         break; 
      default: 
         break; 
   } 
} 
 
void keyboard(unsigned char key, int x, int y) 
{ 
   switch (key) { 
      case 27: 
         exit(0); 
         break; 
   } 
} 
    
/*  
 *  Open window, register input callback functions 
 */ 
int main(int argc, char** argv) 
{ 
   glutInit(&argc, argv); 
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); 
   glutInitWindowSize (500, 500);  
   glutInitWindowPosition (100, 100); 
   glutCreateWindow (argv[0]); 
   glutDisplayFunc(display);  
   glutReshapeFunc(reshape);  
   glutKeyboardFunc (keyboard); 
   glutMouseFunc(mouse); 
   glutMainLoop(); 
   return 0; 
}