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Diffstat (limited to 'progs/redbook/histogram.c')
| -rw-r--r-- | progs/redbook/histogram.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/progs/redbook/histogram.c b/progs/redbook/histogram.c new file mode 100644 index 00000000000..7ddceb69e2e --- /dev/null +++ b/progs/redbook/histogram.c @@ -0,0 +1,201 @@ +/* + * Copyright (c) 1993-2003, Silicon Graphics, Inc. + * All Rights Reserved + * + * Permission to use, copy, modify, and distribute this software for any + * purpose and without fee is hereby granted, provided that the above + * copyright notice appear in all copies and that both the copyright + * notice and this permission notice appear in supporting documentation, + * and that the name of Silicon Graphics, Inc. not be used in + * advertising or publicity pertaining to distribution of the software + * without specific, written prior permission. + * + * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND + * WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE, + * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR + * FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON + * GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT, + * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, + * OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF + * PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD + * PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN ADVISED OF + * THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE + * OR PERFORMANCE OF THIS SOFTWARE. + * + * US Government Users Restricted Rights + * Use, duplication, or disclosure by the Government is subject to + * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph + * (c)(1)(ii) of the Rights in Technical Data and Computer Software + * clause at DFARS 252.227-7013 and/or in similar or successor clauses + * in the FAR or the DOD or NASA FAR Supplement. Unpublished - rights + * reserved under the copyright laws of the United States. + * + * Contractor/manufacturer is: + * Silicon Graphics, Inc. + * 1500 Crittenden Lane + * Mountain View, CA 94043 + * United State of America + * + * OpenGL(R) is a registered trademark of Silicon Graphics, Inc. + */ + +/* + * histogram.c + * Compute the histogram of the image. This program illustrates the + * use of the glHistogram() function. + */ + +#include <GL/glut.h> +#include <assert.h> +#include <stdlib.h> +#include <stdio.h> + +#define HISTOGRAM_SIZE 256 /* Must be a power of 2 */ + + +static GLubyte *pixels; +static GLsizei width, height; + + + +static GLuint bswap(GLuint x) +{ + const GLuint ui = 1; + const GLubyte *ubp = (const GLubyte *) &ui; + if (*ubp == 1) { + /* we're on little endiang so byteswap x */ + GLsizei y = ((x >> 24) + | ((x >> 8) & 0xff00) + | ((x << 8) & 0xff0000) + | ((x << 24) & 0xff000000)); + return y; + } + else { + return x; + } +} + + +static GLubyte* +readImage( const char* filename, GLsizei* width, GLsizei *height ) +{ + int n; + GLubyte* pixels; + + FILE* infile = fopen( filename, "rb" ); + + if ( !infile ) { + fprintf( stderr, "Unable to open file '%s'\n", filename ); + exit(1); + } + + fread( width, sizeof( GLsizei ), 1, infile ); + fread( height, sizeof( GLsizei ), 1, infile ); + + *width = bswap(*width); + *height = bswap(*height); + + n = 3 * (*width) * (*height); + + pixels = (GLubyte *) malloc( n * sizeof( GLubyte )); + if ( !pixels ) { + fprintf( stderr, "Unable to malloc() bytes for pixels\n" ); + return NULL; + } + + fread( pixels, sizeof( GLubyte ), n, infile ); + + fclose( infile ); + + return pixels; +} + +static void init(void) +{ + glPixelStorei(GL_UNPACK_ALIGNMENT, 1); + glClearColor(0.0, 0.0, 0.0, 0.0); + + glHistogram(GL_HISTOGRAM, HISTOGRAM_SIZE, GL_RGB, GL_FALSE); + glEnable(GL_HISTOGRAM); +} + +static void display(void) +{ + int i; + GLushort values[HISTOGRAM_SIZE][3]; + + glClear(GL_COLOR_BUFFER_BIT); + glRasterPos2i(1, 1); + glDrawPixels(width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels); + + glGetHistogram(GL_HISTOGRAM, GL_TRUE, GL_RGB, GL_UNSIGNED_SHORT, values); + + /* Plot histogram */ + + glBegin(GL_LINE_STRIP); + glColor3f(1.0, 0.0, 0.0); + for ( i = 0; i < HISTOGRAM_SIZE; i++ ) + glVertex2s(i, values[i][0]); + glEnd(); + + glBegin(GL_LINE_STRIP); + glColor3f(0.0, 1.0, 0.0); + for ( i = 0; i < HISTOGRAM_SIZE; i++ ) + glVertex2s(i, values[i][1]); + glEnd(); + + glBegin(GL_LINE_STRIP); + glColor3f(0.0, 0.0, 1.0); + for ( i = 0; i < HISTOGRAM_SIZE; i++ ) + glVertex2s(i, values[i][2]); + glEnd(); + glFlush(); +} + +static void reshape(int w, int h) +{ + glViewport(0, 0, (GLsizei) w, (GLsizei) h); + glMatrixMode(GL_PROJECTION); + glLoadIdentity(); + glOrtho(0, 256, 0, 10000, -1.0, 1.0); + glMatrixMode(GL_MODELVIEW); +} + +static void keyboard(unsigned char key, int x, int y) +{ + static GLboolean sink = GL_FALSE; + + switch (key) { + case 's' : + sink = !sink; + glHistogram(GL_HISTOGRAM, HISTOGRAM_SIZE, GL_RGB, sink); + break; + + case 27: + exit(0); + } + glutPostRedisplay(); + +} + +/* Main Loop + * Open window with initial window size, title bar, + * RGBA display mode, and handle input events. + */ +int main(int argc, char** argv) +{ + pixels = readImage("leeds.bin", &width, &height); + + glutInit(&argc, argv); + glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); + glutInitWindowSize(width, height); + glutInitWindowPosition(100, 100); + glutCreateWindow(argv[0]); + init(); + glutReshapeFunc(reshape); + glutKeyboardFunc(keyboard); + glutDisplayFunc(display); + glutMainLoop(); + return 0; +} |