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 * Unpublished-- rights reserved under the copyright laws of the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

/*  multitex.c
 */
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>

#ifdef GL_VERSION_1_2

static GLubyte texels0[32][32][4];
static GLubyte texels1[16][16][4];

void makeCheckImages(void)
{
   int i, j;
    
   for (i = 0; i < 32; i++) {
      for (j = 0; j < 32; j++) {
         texels0[i][j][0] = (GLubyte) i;
         texels0[i][j][1] = (GLubyte) j;
         texels0[i][j][2] = (GLubyte) (i*j)/255;
         texels0[i][j][3] = (GLubyte) 255;
      }
   }

   for (i = 0; i < 16; i++) {
      for (j = 0; j < 16; j++) {
         texels1[i][j][0] = (GLubyte) 255;
         texels1[i][j][1] = (GLubyte) i;
         texels1[i][j][2] = (GLubyte) j;
         texels1[i][j][3] = (GLubyte) 255;
      }
   }
}

void init(void)
{    
   GLuint texNames[2];

   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   makeCheckImages();
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

   glGenTextures(2, texNames);
   glBindTexture(GL_TEXTURE_2D, texNames[0]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA, 
		GL_UNSIGNED_BYTE, texels0);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, 
                   GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
                   GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

   glBindTexture(GL_TEXTURE_2D, texNames[1]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, 
		GL_UNSIGNED_BYTE, texels1);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
   /*  Use the two texture objects to define two texture units
    *  for use in multitexturing  */
   glActiveTextureARB (GL_TEXTURE0_ARB);
   glEnable(GL_TEXTURE_2D);
   glBindTexture(GL_TEXTURE_2D, texNames[0]);
   glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
   glMatrixMode (GL_TEXTURE);
      glLoadIdentity();
      glTranslatef(0.5f, 0.5f, 0.0f);
      glRotatef(45.0f, 0.0f, 0.0f, 1.0f);
      glTranslatef(-0.5f, -0.5f, 0.0f);
   glMatrixMode (GL_MODELVIEW);
   glActiveTextureARB (GL_TEXTURE1_ARB);
   glEnable(GL_TEXTURE_2D);
   glBindTexture(GL_TEXTURE_2D, texNames[1]);
   glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
}

void display(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glBegin(GL_TRIANGLES);
   glMultiTexCoord2fARB (GL_TEXTURE0_ARB, 0.0, 0.0);
   glMultiTexCoord2fARB (GL_TEXTURE1_ARB, 1.0, 0.0);
   glVertex2f(0.0, 0.0);
   glMultiTexCoord2fARB (GL_TEXTURE0_ARB, 0.5, 1.0);
   glMultiTexCoord2fARB (GL_TEXTURE1_ARB, 0.5, 0.0);
   glVertex2f(50.0, 100.0);
   glMultiTexCoord2fARB (GL_TEXTURE0_ARB, 1.0, 0.0);
   glMultiTexCoord2fARB (GL_TEXTURE1_ARB, 1.0, 1.0);
   glVertex2f(100.0, 0.0);
   glEnd();
   glFlush();
}

void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   if (w <= h)
      gluOrtho2D(0.0, 100.0, 0.0, 100.0 * (GLdouble)h/(GLdouble)w);
   else
      gluOrtho2D(0.0, 100.0 * (GLdouble)w/(GLdouble)h, 0.0, 100.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
         exit(0);
         break;
   }
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(250, 250);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);
   init();
   glutReshapeFunc(reshape);
   glutDisplayFunc(display);
   glutKeyboardFunc (keyboard);
   glutMainLoop();
   return 0; 
}
#else
int main(int argc, char** argv)
{
    fprintf (stderr, "This program demonstrates a feature which is not in OpenGL Version 1.0 or 1.1.\n");
    fprintf (stderr, "If your implementation of OpenGL Version 1.0 has the right extensions,\n");
    fprintf (stderr, "you may be able to modify this program to make it run.\n");
    return 0;
}
#endif