www.pudn.com > openglbk.rar > image.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 * Unpublished-- rights reserved under the copyright laws of the 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. 
 */ 
 
/*  image.c 
 *  This program demonstrates drawing pixels and shows the effect 
 *  of glDrawPixels(), glCopyPixels(), and glPixelZoom(). 
 *  Interaction: moving the mouse while pressing the mouse button 
 *  will copy the image in the lower-left corner of the window 
 *  to the mouse position, using the current pixel zoom factors. 
 *  There is no attempt to prevent you from drawing over the original 
 *  image.  If you press the 'r' key, the original image and zoom 
 *  factors are reset.  If you press the 'z' or 'Z' keys, you change 
 *  the zoom factors. 
 */ 
#include  
#include  
#include  
 
/*	Create checkerboard image	*/ 
#define	checkImageWidth 64 
#define	checkImageHeight 64 
GLubyte checkImage[checkImageHeight][checkImageWidth][3]; 
 
static GLdouble zoomFactor = 1.0; 
static GLint height; 
 
void makeCheckImage(void) 
{ 
   int i, j, c; 
     
   for (i = 0; i < checkImageHeight; i++) { 
      for (j = 0; j < checkImageWidth; j++) { 
         c = ((((i&0x8)==0)^((j&0x8))==0))*255; 
         checkImage[i][j][0] = (GLubyte) c; 
         checkImage[i][j][1] = (GLubyte) c; 
         checkImage[i][j][2] = (GLubyte) c; 
      } 
   } 
} 
 
void init(void) 
{     
   glClearColor (0.0, 0.0, 0.0, 0.0); 
   glShadeModel(GL_FLAT); 
   makeCheckImage(); 
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1); 
} 
 
void display(void) 
{ 
   glClear(GL_COLOR_BUFFER_BIT); 
   glRasterPos2i(0, 0); 
   glDrawPixels(checkImageWidth, checkImageHeight, GL_RGB,  
                GL_UNSIGNED_BYTE, checkImage); 
   glFlush(); 
} 
 
void reshape(int w, int h) 
{ 
   glViewport(0, 0, (GLsizei) w, (GLsizei) h); 
   height = (GLint) h; 
   glMatrixMode(GL_PROJECTION); 
   glLoadIdentity(); 
   gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h); 
   glMatrixMode(GL_MODELVIEW); 
   glLoadIdentity(); 
} 
 
void motion(int x, int y) 
{ 
   static GLint screeny; 
    
   screeny = height - (GLint) y; 
   glRasterPos2i (x, screeny); 
   glPixelZoom (zoomFactor, zoomFactor); 
   glCopyPixels (0, 0, checkImageWidth, checkImageHeight, GL_COLOR); 
   glPixelZoom (1.0, 1.0); 
   glFlush (); 
} 
 
void keyboard(unsigned char key, int x, int y) 
{ 
   switch (key) { 
      case 'r': 
      case 'R': 
         zoomFactor = 1.0; 
         glutPostRedisplay(); 
         printf ("zoomFactor reset to 1.0\n"); 
         break; 
      case 'z': 
         zoomFactor += 0.5; 
         if (zoomFactor >= 3.0)  
            zoomFactor = 3.0; 
         printf ("zoomFactor is now %4.1f\n", zoomFactor); 
         break; 
      case 'Z': 
         zoomFactor -= 0.5; 
         if (zoomFactor <= 0.5)  
            zoomFactor = 0.5; 
         printf ("zoomFactor is now %4.1f\n", zoomFactor); 
         break; 
      case 27: 
         exit(0); 
         break; 
      default: 
         break; 
   } 
} 
 
int main(int argc, char** argv) 
{ 
   glutInit(&argc, argv); 
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); 
   glutInitWindowSize(250, 250); 
   glutInitWindowPosition(100, 100); 
   glutCreateWindow(argv[0]); 
   init(); 
   glutDisplayFunc(display); 
   glutReshapeFunc(reshape); 
   glutKeyboardFunc(keyboard); 
   glutMotionFunc(motion); 
   glutMainLoop(); 
   return 0;  
}