progs/redbook/double.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  31  * Unpublished-- rights reserved under the copyright laws of the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  *  double.c
  40  *  This is a simple double buffered program.
  41  *  Pressing the left mouse button rotates the rectangle.
  42  *  Pressing the middle mouse button stops the rotation.
  43  */
  44 #include <GL/glut.h>
  45 #include <stdlib.h>
  46
  47 static GLfloat spin = 0.0;
  48 static GLdouble t0 = 0.;
  49
  50 static void display(void)
  51 {
  52    glClear(GL_COLOR_BUFFER_BIT);
  53    glPushMatrix();
  54    glRotatef(spin, 0.0, 0.0, 1.0);
  55    glColor3f(1.0, 1.0, 1.0);
  56    glRectf(-25.0, -25.0, 25.0, 25.0);
  57    glPopMatrix();
  58
  59    glutSwapBuffers();
  60 }
  61
  62 static GLdouble gettime(void)
  63 {
  64     return (GLdouble)(glutGet(GLUT_ELAPSED_TIME)) / 1000.;
  65 }
  66
  67 static void spinDisplay(void)
  68 {
  69    GLdouble t, dt;
  70    t = gettime();
  71    dt = t - t0;
  72    t0 = t;
  73    spin = spin + 120.0*dt;
  74    if (spin > 360.0)
  75       spin = spin - 360.0;
  76    glutPostRedisplay();
  77 }
  78
  79 static void init(void)
  80 {
  81    glClearColor (0.0, 0.0, 0.0, 0.0);
  82    glShadeModel (GL_FLAT);
  83 }
  84
  85 static void reshape(int w, int h)
  86 {
  87    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
  88    glMatrixMode(GL_PROJECTION);
  89    glLoadIdentity();
  90    glOrtho(-50.0, 50.0, -50.0, 50.0, -1.0, 1.0);
  91    glMatrixMode(GL_MODELVIEW);
  92    glLoadIdentity();
  93 }
  94
  95 /* ARGSUSED2 */
  96 static void mouse(int button, int state, int x, int y)
  97 {
  98    switch (button) {
  99       case GLUT_LEFT_BUTTON:
 100          if (state == GLUT_DOWN)
 101          {
 102             t0 = gettime();
 103             glutIdleFunc(spinDisplay);
 104          }
 105          break;
 106       case GLUT_MIDDLE_BUTTON:
 107          if (state == GLUT_DOWN)
 108             glutIdleFunc(NULL);
 109          break;
 110       default:
 111          break;
 112    }
 113 }
 114
 115 static void
 116 key(unsigned char k, int x, int y)
 117 {
 118   switch (k) {
 119   case 27:  /* Escape */
 120     exit(0);
 121     break;
 122   default:
 123     return;
 124   }
 125   glutPostRedisplay();
 126 }
 127
 128 /*
 129  *  Request double buffer display mode.
 130  *  Register mouse input callback functions
 131  */
 132 int main(int argc, char** argv)
 133 {
 134    glutInit(&argc, argv);
 135    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
 136    glutInitWindowSize (250, 250);
 137    glutInitWindowPosition (100, 100);
 138    glutCreateWindow (argv[0]);
 139    init ();
 140    glutDisplayFunc(display);
 141    glutReshapeFunc(reshape);
 142    glutMouseFunc(mouse);
 143    glutKeyboardFunc(key);
 144    glutMainLoop();
 145    return 0;   /* ANSI C requires main to return int. */
 146 }