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 * Unpublished-- rights reserved under the copyright laws of the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

/*  mipmap.c
 *  This program demonstrates using mipmaps for texture maps.
 *  To overtly show the effect of mipmaps, each mipmap reduction
 *  level has a solidly colored, contrasting texture image.
 *  Thus, the quadrilateral which is drawn is drawn with several
 *  different colors.
 */
#include <GL/glut.h>
#include <stdlib.h>

GLubyte mipmapImage32[32][32][4];
GLubyte mipmapImage16[16][16][4];
GLubyte mipmapImage8[8][8][4];
GLubyte mipmapImage4[4][4][4];
GLubyte mipmapImage2[2][2][4];
GLubyte mipmapImage1[1][1][4];

#ifdef GL_VERSION_1_1
static GLuint texName;
#endif

void makeImages(void)
{
   int i, j;
    
   for (i = 0; i < 32; i++) {
      for (j = 0; j < 32; j++) {
         mipmapImage32[i][j][0] = 255;
         mipmapImage32[i][j][1] = 255;
         mipmapImage32[i][j][2] = 0;
         mipmapImage32[i][j][3] = 255;
      }
   }
   for (i = 0; i < 16; i++) {
      for (j = 0; j < 16; j++) {
         mipmapImage16[i][j][0] = 255;
         mipmapImage16[i][j][1] = 0;
         mipmapImage16[i][j][2] = 255;
         mipmapImage16[i][j][3] = 255;
      }
   }
   for (i = 0; i < 8; i++) {
      for (j = 0; j < 8; j++) {
         mipmapImage8[i][j][0] = 255;
         mipmapImage8[i][j][1] = 0;
         mipmapImage8[i][j][2] = 0;
         mipmapImage8[i][j][3] = 255;
      }
   }
   for (i = 0; i < 4; i++) {
      for (j = 0; j < 4; j++) {
         mipmapImage4[i][j][0] = 0;
         mipmapImage4[i][j][1] = 255;
         mipmapImage4[i][j][2] = 0;
         mipmapImage4[i][j][3] = 255;
      }
   }
   for (i = 0; i < 2; i++) {
      for (j = 0; j < 2; j++) {
         mipmapImage2[i][j][0] = 0;
         mipmapImage2[i][j][1] = 0;
         mipmapImage2[i][j][2] = 255;
         mipmapImage2[i][j][3] = 255;
      }
   }
   mipmapImage1[0][0][0] = 255;
   mipmapImage1[0][0][1] = 255;
   mipmapImage1[0][0][2] = 255;
   mipmapImage1[0][0][3] = 255;
}

void init(void)
{    
   glEnable(GL_DEPTH_TEST);
   glShadeModel(GL_FLAT);

   glTranslatef(0.0, 0.0, -3.6);
   makeImages();
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

#ifdef GL_VERSION_1_1
   glGenTextures(1, &texName);
   glBindTexture(GL_TEXTURE_2D, texName);
#endif
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
                   GL_NEAREST_MIPMAP_NEAREST);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, mipmapImage32);
   glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, 16, 16, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, mipmapImage16);
   glTexImage2D(GL_TEXTURE_2D, 2, GL_RGBA, 8, 8, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, mipmapImage8);
   glTexImage2D(GL_TEXTURE_2D, 3, GL_RGBA, 4, 4, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, mipmapImage4);
   glTexImage2D(GL_TEXTURE_2D, 4, GL_RGBA, 2, 2, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, mipmapImage2);
   glTexImage2D(GL_TEXTURE_2D, 5, GL_RGBA, 1, 1, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, mipmapImage1);

   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
   glEnable(GL_TEXTURE_2D);
}

void display(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
#ifdef GL_VERSION_1_1
   glBindTexture(GL_TEXTURE_2D, texName);
#endif
   glBegin(GL_QUADS);
   glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
   glTexCoord2f(0.0, 8.0); glVertex3f(-2.0, 1.0, 0.0);
   glTexCoord2f(8.0, 8.0); glVertex3f(2000.0, 1.0, -6000.0);
   glTexCoord2f(8.0, 0.0); glVertex3f(2000.0, -1.0, -6000.0);
   glEnd();
   glFlush();
}

void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(60.0, (GLfloat)w/(GLfloat)h, 1.0, 30000.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

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

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize (500, 500);
   glutInitWindowPosition (50, 50);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0;     
}