progs/redbook/checker.c

   1
   2 /* Copyright (c) Mark J. Kilgard, 1994. */
   3
   4 /*
   5  * (c) Copyright 1993, Silicon Graphics, Inc.
   6  * ALL RIGHTS RESERVED
   7  * Permission to use, copy, modify, and distribute this software for
   8  * any purpose and without fee is hereby granted, provided that the above
   9  * copyright notice appear in all copies and that both the copyright notice
  10  * and this permission notice appear in supporting documentation, and that
  11  * the name of Silicon Graphics, Inc. not be used in advertising
  12  * or publicity pertaining to distribution of the software without specific,
  13  * written prior permission.
  14  *
  15  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
  16  * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  18  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  19  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  20  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
  21  * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
  22  * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
  23  * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
  24  * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
  25  * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
  26  * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
  27  *
  28  * US Government Users Restricted Rights
  29  * Use, duplication, or disclosure by the Government is subject to
  30  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  31  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  32  * clause at DFARS 252.227-7013 and/or in similar or successor
  33  * clauses in the FAR or the DOD or NASA FAR Supplement.
  34  * Unpublished-- rights reserved under the copyright laws of the
  35  * United States.  Contractor/manufacturer is Silicon Graphics,
  36  * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
  37  *
  38  * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
  39  */
  40 /*  checker.c
  41  *  This program texture maps a checkerboard image onto
  42  *  two rectangles.  This program clamps the texture, if
  43  *  the texture coordinates fall outside 0.0 and 1.0.
  44  */
  45 #include <stdlib.h>
  46 #include <GL/glut.h>
  47
  48 /*      Create checkerboard texture     */
  49 #define checkImageWidth 64
  50 #define checkImageHeight 64
  51 GLubyte checkImage[checkImageWidth][checkImageHeight][3];
  52
  53 void makeCheckImage(void)
  54 {
  55     int i, j, c;
  56
  57     for (i = 0; i < checkImageWidth; i++) {
  58         for (j = 0; j < checkImageHeight; j++) {
  59             c = ((((i&0x8)==0)^((j&0x8)==0)))*255;
  60             checkImage[i][j][0] = (GLubyte) c;
  61             checkImage[i][j][1] = (GLubyte) c;
  62             checkImage[i][j][2] = (GLubyte) c;
  63         }
  64     }
  65 }
  66
  67 void myinit(void)
  68 {
  69     glClearColor (0.0, 0.0, 0.0, 0.0);
  70     glEnable(GL_DEPTH_TEST);
  71     glDepthFunc(GL_LESS);
  72
  73     makeCheckImage();
  74     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  75     glTexImage2D(GL_TEXTURE_2D, 0, 3, checkImageWidth,
  76         checkImageHeight, 0, GL_RGB, GL_UNSIGNED_BYTE,
  77         &checkImage[0][0][0]);
  78     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
  79     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
  80     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  81     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  82     glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
  83     glEnable(GL_TEXTURE_2D);
  84     glShadeModel(GL_FLAT);
  85 }
  86
  87 void display(void)
  88 {
  89     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  90     glBegin(GL_QUADS);
  91     glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
  92     glTexCoord2f(0.0, 1.0); glVertex3f(-2.0, 1.0, 0.0);
  93     glTexCoord2f(1.0, 1.0); glVertex3f(0.0, 1.0, 0.0);
  94     glTexCoord2f(1.0, 0.0); glVertex3f(0.0, -1.0, 0.0);
  95
  96     glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0);
  97     glTexCoord2f(0.0, 1.0); glVertex3f(1.0, 1.0, 0.0);
  98     glTexCoord2f(1.0, 1.0); glVertex3f(2.41421, 1.0, -1.41421);
  99     glTexCoord2f(1.0, 0.0); glVertex3f(2.41421, -1.0, -1.41421);
 100     glEnd();
 101     glutSwapBuffers();
 102 }
 103
 104 void myReshape(int w, int h)
 105 {
 106     glViewport(0, 0, w, h);
 107     glMatrixMode(GL_PROJECTION);
 108     glLoadIdentity();
 109     gluPerspective(60.0, 1.0*(GLfloat)w/(GLfloat)h, 1.0, 30.0);
 110     glMatrixMode(GL_MODELVIEW);
 111     glLoadIdentity();
 112     glTranslatef(0.0, 0.0, -3.6);
 113 }
 114
 115 static void
 116 key(unsigned char k, int x, int y)
 117 {
 118   switch (k) {
 119   case 27:  /* Escape */
 120     exit(0);
 121     break;
 122   default:
 123     return;
 124   }
 125   glutPostRedisplay();
 126 }
 127
 128 int
 129 main(int argc, char** argv)
 130 {
 131     glutInit(&argc, argv);
 132     glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
 133     glutCreateWindow("checker");
 134     myinit();
 135     glutReshapeFunc (myReshape);
 136     glutDisplayFunc(display);
 137     glutKeyboardFunc(key);
 138     glutMainLoop();
 139     return 0;             /* ANSI C requires main to return int. */
 140 }