checker.c revision 32001f49 
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34 * Unpublished-- rights reserved under the copyright laws of the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 "glut_wrap.h"
47
48/*	Create checkerboard texture	*/
49#define	checkImageWidth 64
50#define	checkImageHeight 64
51GLubyte checkImage[checkImageWidth][checkImageHeight][3];
52
53static 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
67static 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
87static 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
104static 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
115static void
116key(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
128int
129main(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}
141