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("First Tri") == GL_FALSE
) {
152 glutReshapeFunc(Reshape
);
153 glutKeyboardFunc(Key
);
154 glutDisplayFunc(Draw
);