progs/redbook/unproject.c

   1 /*
   2  * Copyright (c) 1993-1997, Silicon Graphics, Inc.
   3  * ALL RIGHTS RESERVED
   4  * Permission to use, copy, modify, and distribute this software for
   5  * any purpose and without fee is hereby granted, provided that the above
   6  * copyright notice appear in all copies and that both the copyright notice
   7  * and this permission notice appear in supporting documentation, and that
   8  * the name of Silicon Graphics, Inc. not be used in advertising
   9  * or publicity pertaining to distribution of the software without specific,
  10  * written prior permission.
  11  *
  12  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
  13  * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  14  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  15  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  16  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  17  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
  18  * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
  19  * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
  20  * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
  21  * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
  22  * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
  23  * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
  24  *
  25  * US Government Users Restricted Rights
  26  * Use, duplication, or disclosure by the Government is subject to
  27  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  28  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  29  * clause at DFARS 252.227-7013 and/or in similar or successor
  30  * clauses in the FAR or the DOD or NASA FAR Supplement.
  31  * Unpublished-- rights reserved under the copyright laws of the
  32  * United States.  Contractor/manufacturer is Silicon Graphics,
  33  * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
  34  *
  35  * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
  36  */
  37
  38 /*
  39  *  unproject.c
  40  *  When the left mouse button is pressed, this program
  41  *  reads the mouse position and determines two 3D points
  42  *  from which it was transformed.  Very little is displayed.
  43  */
  44 #include <GL/glut.h>
  45 #include <stdlib.h>
  46 #include <stdio.h>
  47
  48 void display(void)
  49 {
  50    glClear(GL_COLOR_BUFFER_BIT);
  51    glFlush();
  52 }
  53
  54 /* Change these values for a different transformation  */
  55 void reshape(int w, int h)
  56 {
  57    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
  58    glMatrixMode(GL_PROJECTION);
  59    glLoadIdentity();
  60    gluPerspective (45.0, (GLfloat) w/(GLfloat) h, 1.0, 100.0);
  61    glMatrixMode(GL_MODELVIEW);
  62    glLoadIdentity();
  63 }
  64
  65 void mouse(int button, int state, int x, int y)
  66 {
  67    GLint viewport[4];
  68    GLdouble mvmatrix[16], projmatrix[16];
  69    GLint realy;  /*  OpenGL y coordinate position  */
  70    GLdouble wx, wy, wz;  /*  returned world x, y, z coords  */
  71
  72    switch (button) {
  73       case GLUT_LEFT_BUTTON:
  74          if (state == GLUT_DOWN) {
  75             glGetIntegerv (GL_VIEWPORT, viewport);
  76             glGetDoublev (GL_MODELVIEW_MATRIX, mvmatrix);
  77             glGetDoublev (GL_PROJECTION_MATRIX, projmatrix);
  78 /*  note viewport[3] is height of window in pixels  */
  79             realy = viewport[3] - (GLint) y - 1;
  80             printf ("Coordinates at cursor are (%4d, %4d)\n", x, realy);
  81             gluUnProject ((GLdouble) x, (GLdouble) realy, 0.0,
  82                mvmatrix, projmatrix, viewport, &wx, &wy, &wz);
  83             printf ("World coords at z=0.0 are (%f, %f, %f)\n",
  84                wx, wy, wz);
  85             gluUnProject ((GLdouble) x, (GLdouble) realy, 1.0,
  86                mvmatrix, projmatrix, viewport, &wx, &wy, &wz);
  87             printf ("World coords at z=1.0 are (%f, %f, %f)\n",
  88                wx, wy, wz);
  89          }
  90          break;
  91       case GLUT_RIGHT_BUTTON:
  92          if (state == GLUT_DOWN)
  93             exit(0);
  94          break;
  95       default:
  96          break;
  97    }
  98 }
  99
 100 /* ARGSUSED1 */
 101 void keyboard(unsigned char key, int x, int y)
 102 {
 103    switch (key) {
 104       case 27:
 105          exit(0);
 106          break;
 107    }
 108 }
 109
 110 /*
 111  *  Open window, register input callback functions
 112  */
 113 int main(int argc, char** argv)
 114 {
 115    glutInit(&argc, argv);
 116    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
 117    glutInitWindowSize (500, 500);
 118    glutInitWindowPosition (100, 100);
 119    glutCreateWindow (argv[0]);
 120    glutDisplayFunc(display);
 121    glutReshapeFunc(reshape);
 122    glutKeyboardFunc (keyboard);
 123    glutMouseFunc(mouse);
 124    glutMainLoop();
 125    return 0;
 126 }