progs/redbook/histogram.c

   1 /*
   2  * Copyright (c) 1993-2003, Silicon Graphics, Inc.
   3  * All Rights Reserved
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose and without fee is hereby granted, provided that the above
   7  * copyright notice appear in all copies and that both the copyright
   8  * notice and this permission notice appear in supporting documentation,
   9  * and that the name of Silicon Graphics, Inc. not be used in
  10  * advertising or publicity pertaining to distribution of the software
  11  * without specific, written prior permission.
  12  *
  13  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND
  14  * WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  16  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  17  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  18  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF
  20  * PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD
  21  * PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN ADVISED OF
  22  * THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF
  23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE
  24  * OR PERFORMANCE OF THIS SOFTWARE.
  25  *
  26  * US Government Users Restricted Rights
  27  * Use, duplication, or disclosure by the Government is subject to
  28  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  29  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  30  * clause at DFARS 252.227-7013 and/or in similar or successor clauses
  31  * in the FAR or the DOD or NASA FAR Supplement.  Unpublished - rights
  32  * reserved under the copyright laws of the United States.
  33  *
  34  * Contractor/manufacturer is:
  35  *      Silicon Graphics, Inc.
  36  *      1500 Crittenden Lane
  37  *      Mountain View, CA  94043
  38  *      United State of America
  39  *
  40  * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
  41  */
  42
  43 /*
  44  *  histogram.c
  45  *  Compute the histogram of the image.  This program illustrates the
  46  *  use of the glHistogram() function.
  47  */
  48
  49 #include <GL/glew.h>
  50 #include <GL/glut.h>
  51 #include <assert.h>
  52 #include <stdlib.h>
  53 #include <stdio.h>
  54
  55 #define HISTOGRAM_SIZE  256   /* Must be a power of 2 */
  56
  57
  58 static GLubyte  *pixels;
  59 static GLsizei   width, height;
  60
  61
  62
  63 static GLuint bswap(GLuint x)
  64 {
  65    const GLuint ui = 1;
  66    const GLubyte *ubp = (const GLubyte *) &ui;
  67    if (*ubp == 1) {
  68       /* we're on little endiang so byteswap x */
  69       GLsizei y =  ((x >> 24)
  70                     | ((x >> 8) & 0xff00)
  71                     | ((x << 8) & 0xff0000)
  72                     | ((x << 24) & 0xff000000));
  73       return y;
  74    }
  75    else {
  76       return x;
  77    }
  78 }
  79
  80
  81 static GLubyte*
  82 readImage( const char* filename, GLsizei* width, GLsizei *height )
  83 {
  84     int       n;
  85     GLubyte*  pixels;
  86     size_t    num_read;
  87
  88     FILE* infile = fopen( filename, "rb" );
  89
  90     if ( !infile ) {
  91         fprintf( stderr, "Unable to open file '%s'\n", filename );
  92         exit(1);
  93     }
  94
  95     num_read = fread( width, sizeof( GLsizei ), 1, infile );
  96     assert(num_read == 1);
  97     num_read = fread( height, sizeof( GLsizei ), 1, infile );
  98     assert(num_read == 1);
  99
 100     *width = bswap(*width);
 101     *height = bswap(*height);
 102
 103     n = 3 * (*width) * (*height);
 104
 105     pixels = (GLubyte *) malloc( n * sizeof( GLubyte ));
 106     if ( !pixels ) {
 107         fprintf( stderr, "Unable to malloc() bytes for pixels\n" );
 108         fclose( infile );
 109         return NULL;
 110     }
 111
 112     num_read = fread( pixels, sizeof( GLubyte ), n, infile );
 113     assert(num_read == n);
 114
 115     fclose( infile );
 116
 117     return pixels;
 118 }
 119
 120 static void init(void)
 121 {
 122    if (!glutExtensionSupported("GL_ARB_imaging")) {
 123       fprintf(stderr, "Sorry, this program requires GL_ARB_imaging.\n");
 124       exit(1);
 125    }
 126
 127    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 128    glClearColor(0.0, 0.0, 0.0, 0.0);
 129
 130    glHistogram(GL_HISTOGRAM, HISTOGRAM_SIZE, GL_RGB, GL_FALSE);
 131    glEnable(GL_HISTOGRAM);
 132 }
 133
 134 static void display(void)
 135 {
 136    int i;
 137    GLushort values[HISTOGRAM_SIZE][3];
 138
 139    glClear(GL_COLOR_BUFFER_BIT);
 140    glRasterPos2i(1, 1);
 141    glDrawPixels(width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels);
 142
 143    glGetHistogram(GL_HISTOGRAM, GL_TRUE, GL_RGB, GL_UNSIGNED_SHORT, values);
 144
 145    /* Plot histogram */
 146
 147    glBegin(GL_LINE_STRIP);
 148    glColor3f(1.0, 0.0, 0.0);
 149    for ( i = 0; i < HISTOGRAM_SIZE; i++ )
 150        glVertex2s(i, values[i][0]);
 151    glEnd();
 152
 153    glBegin(GL_LINE_STRIP);
 154    glColor3f(0.0, 1.0, 0.0);
 155    for ( i = 0; i < HISTOGRAM_SIZE; i++ )
 156        glVertex2s(i, values[i][1]);
 157    glEnd();
 158
 159    glBegin(GL_LINE_STRIP);
 160    glColor3f(0.0, 0.0, 1.0);
 161    for ( i = 0; i < HISTOGRAM_SIZE; i++ )
 162        glVertex2s(i, values[i][2]);
 163    glEnd();
 164    glFlush();
 165 }
 166
 167 static void reshape(int w, int h)
 168 {
 169    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
 170    glMatrixMode(GL_PROJECTION);
 171    glLoadIdentity();
 172    glOrtho(0, 256, 0, 10000, -1.0, 1.0);
 173    glMatrixMode(GL_MODELVIEW);
 174 }
 175
 176 static void keyboard(unsigned char key, int x, int y)
 177 {
 178    static GLboolean sink = GL_FALSE;
 179
 180    switch (key) {
 181       case 's' :
 182           sink = !sink;
 183           glHistogram(GL_HISTOGRAM, HISTOGRAM_SIZE, GL_RGB, sink);
 184           break;
 185
 186       case 27:
 187          exit(0);
 188    }
 189    glutPostRedisplay();
 190
 191 }
 192
 193 /*  Main Loop
 194  *  Open window with initial window size, title bar,
 195  *  RGBA display mode, and handle input events.
 196  */
 197 int main(int argc, char** argv)
 198 {
 199    pixels = readImage("leeds.bin", &width, &height);
 200
 201    glutInit(&argc, argv);
 202    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
 203    glutInitWindowSize(width, height);
 204    glutInitWindowPosition(100, 100);
 205    glutCreateWindow(argv[0]);
 206    glewInit();
 207    init();
 208    glutReshapeFunc(reshape);
 209    glutKeyboardFunc(keyboard);
 210    glutDisplayFunc(display);
 211    glutMainLoop();
 212    return 0;
 213 }