progs/redbook/movelight.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  31  * Unpublished-- rights reserved under the copyright laws of the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  *  movelight.c
  40  *  This program demonstrates when to issue lighting and
  41  *  transformation commands to render a model with a light
  42  *  which is moved by a modeling transformation (rotate or
  43  *  translate).  The light position is reset after the modeling
  44  *  transformation is called.  The eye position does not change.
  45  *
  46  *  A sphere is drawn using a grey material characteristic.
  47  *  A single light source illuminates the object.
  48  *
  49  *  Interaction:  pressing the left mouse button alters
  50  *  the modeling transformation (x rotation) by 30 degrees.
  51  *  The scene is then redrawn with the light in a new position.
  52  */
  53 #include <GL/glut.h>
  54 #include <stdlib.h>
  55
  56 static int spin = 0;
  57
  58 /*  Initialize material property, light source, lighting model,
  59  *  and depth buffer.
  60  */
  61 static void init(void)
  62 {
  63    glClearColor (0.0, 0.0, 0.0, 0.0);
  64    glShadeModel (GL_SMOOTH);
  65    glEnable(GL_LIGHTING);
  66    glEnable(GL_LIGHT0);
  67    glEnable(GL_DEPTH_TEST);
  68 }
  69
  70 /*  Here is where the light position is reset after the modeling
  71  *  transformation (glRotated) is called.  This places the
  72  *  light at a new position in world coordinates.  The cube
  73  *  represents the position of the light.
  74  */
  75 static void display(void)
  76 {
  77    GLfloat position[] = { 0.0, 0.0, 1.5, 1.0 };
  78
  79    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  80    glPushMatrix ();
  81    gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
  82
  83    glPushMatrix ();
  84    glRotated ((GLdouble) spin, 1.0, 0.0, 0.0);
  85    glLightfv (GL_LIGHT0, GL_POSITION, position);
  86
  87    glTranslated (0.0, 0.0, 1.5);
  88    glDisable (GL_LIGHTING);
  89    glColor3f (0.0, 1.0, 1.0);
  90    glutWireCube (0.1);
  91    glEnable (GL_LIGHTING);
  92    glPopMatrix ();
  93
  94    glutSolidTorus (0.275, 0.85, 8, 15);
  95    glPopMatrix ();
  96    glFlush ();
  97 }
  98
  99 static void reshape (int w, int h)
 100 {
 101    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
 102    glMatrixMode (GL_PROJECTION);
 103    glLoadIdentity();
 104    gluPerspective(40.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);
 105    glMatrixMode(GL_MODELVIEW);
 106    glLoadIdentity();
 107 }
 108
 109 /* ARGSUSED2 */
 110 static void mouse(int button, int state, int x, int y)
 111 {
 112    switch (button) {
 113       case GLUT_LEFT_BUTTON:
 114          if (state == GLUT_DOWN) {
 115             spin = (spin + 30) % 360;
 116             glutPostRedisplay();
 117          }
 118          break;
 119       default:
 120          break;
 121    }
 122 }
 123
 124 /* ARGSUSED1 */
 125 static void keyboard(unsigned char key, int x, int y)
 126 {
 127    switch (key) {
 128       case 27:
 129          exit(0);
 130          break;
 131    }
 132 }
 133
 134 int main(int argc, char** argv)
 135 {
 136    glutInit(&argc, argv);
 137    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 138    glutInitWindowSize (500, 500);
 139    glutInitWindowPosition (100, 100);
 140    glutCreateWindow (argv[0]);
 141    init ();
 142    glutDisplayFunc(display);
 143    glutReshapeFunc(reshape);
 144    glutMouseFunc(mouse);
 145    glutKeyboardFunc(keyboard);
 146    glutMainLoop();
 147    return 0;
 148 }