www.pudn.com > openglbk.rar > histogram.c

/* 
 * Copyright (c) 1993-1999, 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 * Unpublished-- rights reserved under the copyright laws of the 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., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311. 
 * 
 * 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  
#include  
 
#define HISTOGRAM_SIZE  256   /* Must be a power of 2 */ 
 
extern GLubyte*  readImage(const char*, GLsizei*, GLsizei*); 
 
GLubyte  *pixels; 
GLsizei   width, height; 
 
 
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); 
} 
 
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(); 
} 
 
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); 
} 
 
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("Data/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; 
}