2 * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
4 * Permission to use, copy, modify, distribute, and sell this software and
5 * its documentation for any purpose is hereby granted without fee, provided
6 * that (i) the above copyright notices and this permission notice appear in
7 * all copies of the software and related documentation, and (ii) the name of
8 * Silicon Graphics may not be used in any advertising or
9 * publicity relating to the software without the specific, prior written
10 * permission of Silicon Graphics.
12 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
14 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
15 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
17 * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
18 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
19 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
20 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
21 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
32 static void Init(void)
34 fprintf(stderr, "GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
35 fprintf(stderr, "GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
36 fprintf(stderr, "GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
38 glClearColor(1.0, 1.0, 1.0, 0.0);
41 static void Reshape(int width, int height)
43 glViewport(0, 0, (GLint)width, (GLint)height);
45 glMatrixMode(GL_PROJECTION);
47 glOrtho(-1.2, 1.2, -1.2, 1.2, -0.5, 1000.0);
48 glMatrixMode(GL_MODELVIEW);
51 static void Key(unsigned char key, int x, int y)
63 static void quad( float half )
66 glVertex3f( half/9.0, -half/9.0, -25.0 + half);
67 glVertex3f( half/9.0, half/9.0, -25.0 + half);
68 glVertex3f(-half/9.0, half/9.0, -25.0 - half);
69 glVertex3f(-half/9.0, -half/9.0, -25.0 - half);
73 static void Draw(void)
75 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
76 glEnable(GL_DEPTH_TEST);
78 /* red: offset back */
79 glEnable(GL_POLYGON_OFFSET_FILL);
80 glPolygonOffset(0, 4);
84 /* black: no offset */
85 glDisable(GL_POLYGON_OFFSET_FILL);
89 /* green: offset 0 (this should obscure the black quad) */
90 glEnable(GL_POLYGON_OFFSET_FILL);
91 glPolygonOffset(0, 0);
92 glDepthFunc( GL_EQUAL );
96 /* blue: offset forward */
97 glDepthFunc( GL_LESS );
98 glPolygonOffset(0, -4);
102 glDisable(GL_POLYGON_OFFSET_FILL);
111 static GLenum Args(int argc, char **argv)
115 doubleBuffer = GL_FALSE;
117 for (i = 1; i < argc; i++) {
118 if (strcmp(argv[i], "-sb") == 0) {
119 doubleBuffer = GL_FALSE;
120 } else if (strcmp(argv[i], "-db") == 0) {
121 doubleBuffer = GL_TRUE;
123 fprintf(stderr, "%s (Bad option).\n", argv[i]);
130 int main(int argc, char **argv)
134 glutInit(&argc, argv);
136 if (Args(argc, argv) == GL_FALSE) {
140 glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
142 type = GLUT_RGB | GLUT_ALPHA | GLUT_DEPTH;
143 type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
144 glutInitDisplayMode(type);
146 if (glutCreateWindow(*argv) == GL_FALSE) {
152 glutReshapeFunc(Reshape);
153 glutKeyboardFunc(Key);
154 glutDisplayFunc(Draw);