progs/redbook/image.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  31  * Unpublished-- rights reserved under the copyright laws of the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 /*  image.c
  39  *  This program demonstrates drawing pixels and shows the effect
  40  *  of glDrawPixels(), glCopyPixels(), and glPixelZoom().
  41  *  Interaction: moving the mouse while pressing the mouse button
  42  *  will copy the image in the lower-left corner of the window
  43  *  to the mouse position, using the current pixel zoom factors.
  44  *  There is no attempt to prevent you from drawing over the original
  45  *  image.  If you press the 'r' key, the original image and zoom
  46  *  factors are reset.  If you press the 'z' or 'Z' keys, you change
  47  *  the zoom factors.
  48  */
  49 #include <GL/glut.h>
  50 #include <stdlib.h>
  51 #include <stdio.h>
  52
  53 /*      Create checkerboard image       */
  54 #define checkImageWidth 64
  55 #define checkImageHeight 64
  56 GLubyte checkImage[checkImageHeight][checkImageWidth][3];
  57
  58 static GLdouble zoomFactor = 1.0;
  59 static GLint height;
  60
  61 void makeCheckImage(void)
  62 {
  63    int i, j, c;
  64
  65    for (i = 0; i < checkImageHeight; i++) {
  66       for (j = 0; j < checkImageWidth; j++) {
  67          c = (((i&0x8)==0)^((j&0x8)==0))*255;
  68          checkImage[i][j][0] = (GLubyte) c;
  69          checkImage[i][j][1] = (GLubyte) c;
  70          checkImage[i][j][2] = (GLubyte) c;
  71       }
  72    }
  73 }
  74
  75 void init(void)
  76 {
  77    glClearColor (0.0, 0.0, 0.0, 0.0);
  78    glShadeModel(GL_FLAT);
  79    makeCheckImage();
  80    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  81 }
  82
  83 void display(void)
  84 {
  85    glClear(GL_COLOR_BUFFER_BIT);
  86    glRasterPos2i(0, 0);
  87    glDrawPixels(checkImageWidth, checkImageHeight, GL_RGB,
  88                 GL_UNSIGNED_BYTE, checkImage);
  89    glFlush();
  90 }
  91
  92 void reshape(int w, int h)
  93 {
  94    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  95    height = (GLint) h;
  96    glMatrixMode(GL_PROJECTION);
  97    glLoadIdentity();
  98    gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h);
  99    glMatrixMode(GL_MODELVIEW);
 100    glLoadIdentity();
 101 }
 102
 103 void motion(int x, int y)
 104 {
 105    static GLint screeny;
 106
 107    screeny = height - (GLint) y;
 108    glRasterPos2i (x, screeny);
 109    glPixelZoom (zoomFactor, zoomFactor);
 110    glCopyPixels (0, 0, checkImageWidth, checkImageHeight, GL_COLOR);
 111    glPixelZoom (1.0, 1.0);
 112    glFlush ();
 113 }
 114
 115 /* ARGSUSED1 */
 116 void keyboard(unsigned char key, int x, int y)
 117 {
 118    switch (key) {
 119       case 'r':
 120       case 'R':
 121          zoomFactor = 1.0;
 122          glutPostRedisplay();
 123          printf ("zoomFactor reset to 1.0\n");
 124          break;
 125       case 'z':
 126          zoomFactor += 0.5;
 127          if (zoomFactor >= 3.0)
 128             zoomFactor = 3.0;
 129          printf ("zoomFactor is now %4.1f\n", zoomFactor);
 130          break;
 131       case 'Z':
 132          zoomFactor -= 0.5;
 133          if (zoomFactor <= 0.5)
 134             zoomFactor = 0.5;
 135          printf ("zoomFactor is now %4.1f\n", zoomFactor);
 136          break;
 137       case 27:
 138          exit(0);
 139          break;
 140       default:
 141          break;
 142    }
 143 }
 144
 145 int main(int argc, char** argv)
 146 {
 147    glutInit(&argc, argv);
 148    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
 149    glutInitWindowSize(250, 250);
 150    glutInitWindowPosition(100, 100);
 151    glutCreateWindow(argv[0]);
 152    init();
 153    glutDisplayFunc(display);
 154    glutReshapeFunc(reshape);
 155    glutKeyboardFunc(keyboard);
 156    glutMotionFunc(motion);
 157    glutMainLoop();
 158    return 0;
 159 }