convolution.c

OpenGL学习资料

/*
 * 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 * Unpublished-- rights reserved under the copyright laws of the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.
 */

/*
 *  convolution.c
 *  Use various 2D convolutions filters to find edges in an image.
 *  
 */
#include <GL/glut.h>
#include <stdlib.h>

extern GLubyte*  readImage(const char*, GLsizei*, GLsizei*);

GLubyte  *pixels;
GLsizei   width, height;

GLfloat  horizontal[3][3] = {
    { 0, -1, 0 },
    { 0,  1, 0 },
    { 0,  0, 0 }
};

GLfloat  vertical[3][3] = {
    {  0, 0, 0 },
    { -1, 1, 0 },
    {  0, 0, 0 }
};

GLfloat  laplacian[3][3] = {
    { -0.125, -0.125, -0.125 },
    { -0.125,  1.0  , -0.125 },
    { -0.125, -0.125, -0.125 },
};


void init(void)
{
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
   glClearColor(0.0, 0.0, 0.0, 0.0);

   printf("Using the horizontal filter\n");
   glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE,
			 3, 3, GL_LUMINANCE, GL_FLOAT, horizontal);
   glEnable(GL_CONVOLUTION_2D);
}

void display(void)
{
   glClear(GL_COLOR_BUFFER_BIT);
   glRasterPos2i( 1, 1);
   glDrawPixels(width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels);
   glFlush();
}

void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(0, w, 0, h, -1.0, 1.0);
   glMatrixMode(GL_MODELVIEW);
}

void keyboard(unsigned char key, int x, int y)
{
   switch (key) {
       case 'h' :
	   printf("Using a horizontal filter\n");
	   glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE, 3, 3,
				  GL_LUMINANCE, GL_FLOAT, horizontal);
	   break;

       case 'v' : 
	   printf("Using the vertical filter\n");
	   glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE, 3, 3,
				  GL_LUMINANCE, GL_FLOAT, vertical);
	   break;

       case 'l' :
	   printf("Using the laplacian filter\n");
	   glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE, 3, 3,
				  GL_LUMINANCE, GL_FLOAT, laplacian);
	   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;
}