2 * Copyright (c) 1993-1997, Silicon Graphics, Inc.
4 * Permission to use, copy, modify, and distribute this software for
5 * any purpose and without fee is hereby granted, provided that the above
6 * copyright notice appear in all copies and that both the copyright notice
7 * and this permission notice appear in supporting documentation, and that
8 * the name of Silicon Graphics, Inc. not be used in advertising
9 * or publicity pertaining to distribution of the software without specific,
10 * written prior permission.
12 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
13 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
14 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
15 * FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
16 * GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
17 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
18 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
19 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
20 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
21 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
22 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
23 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
25 * US Government Users Restricted Rights
26 * Use, duplication, or disclosure by the Government is subject to
27 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
28 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
29 * clause at DFARS 252.227-7013 and/or in similar or successor
30 * clauses in the FAR or the DOD or NASA FAR Supplement.
31 * Unpublished-- rights reserved under the copyright laws of the
32 * United States. Contractor/manufacturer is Silicon Graphics,
33 * Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
35 * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
42 static int leftFirst
= GL_TRUE
;
44 static struct { GLenum func
; const char *str
; } funcs
[] =
46 { GL_LESS
, "GL_LESS" },
47 { GL_LEQUAL
, "GL_LEQUAL" },
48 { GL_GREATER
, "GL_GREATER" },
49 { GL_GEQUAL
, "GL_GEQUAL" },
50 { GL_EQUAL
, "GL_EQUAL" },
51 { GL_NOTEQUAL
, "GL_NOTEQUAL" },
52 { GL_ALWAYS
, "GL_ALWAYS" },
53 { GL_NEVER
, "GL_NEVER" },
56 #define NUM_FUNCS (sizeof(funcs) / sizeof(funcs[0]))
58 static int curFunc
= 0;
59 static double clearVal
= 1.0;
62 static void usage(void)
64 printf("t - toggle rendering order of triangles\n");
65 printf("c - toggle Z clear value between 0, 1\n");
66 printf("f - cycle through depth test functions\n");
70 static void init(void)
72 glEnable(GL_DEPTH_TEST
);
73 glClearColor (1.0, 0.0, 0.0, 0.0);
76 static void drawLeftTriangle(void)
78 /* draw yellow triangle on LHS of screen */
79 glBegin (GL_TRIANGLES
);
80 glColor4f(1.0, 1.0, 0.0, 0.75);
81 glVertex3f(0.1, 0.9, -1.0);
82 glVertex3f(0.1, 0.1, -1.0);
83 glVertex3f(0.8, 0.5, 1.0);
87 static void drawRightTriangle(void)
89 /* draw cyan triangle on RHS of screen */
90 glBegin (GL_TRIANGLES
);
91 glColor4f(0.0, 1.0, 1.0, 0.75);
92 glVertex3f(0.9, 0.9, 0.0);
93 glVertex3f(0.2, 0.5, 0.0);
94 glVertex3f(0.9, 0.1, 0.0);
100 printf("GL_CLEAR_DEPTH = %f GL_DEPTH_FUNC = %s\n",
101 clearVal
, funcs
[curFunc
].str
);
102 glClearDepth(clearVal
);
103 glDepthFunc(funcs
[curFunc
].func
);
105 glClear(GL_COLOR_BUFFER_BIT
| GL_DEPTH_BUFFER_BIT
);
119 void reshape(int w
, int h
)
121 glViewport(0, 0, (GLsizei
) w
, (GLsizei
) h
);
122 glMatrixMode(GL_PROJECTION
);
125 gluOrtho2D (0.0, 1.0, 0.0, 1.0*(GLfloat
)h
/(GLfloat
)w
);
127 gluOrtho2D (0.0, 1.0*(GLfloat
)w
/(GLfloat
)h
, 0.0, 1.0);
131 void keyboard(unsigned char key
, int x
, int y
)
136 clearVal
= 1.0 - clearVal
;
141 curFunc
= (curFunc
+ 1) % NUM_FUNCS
;
146 leftFirst
= !leftFirst
;
149 case 27: /* Escape key */
158 * Open window with initial window size, title bar,
159 * RGBA display mode, and handle input events.
161 int main(int argc
, char** argv
)
163 glutInit(&argc
, argv
);
164 glutInitDisplayMode (GLUT_SINGLE
| GLUT_RGB
| GLUT_DEPTH
);
165 glutInitWindowSize (200, 200);
166 glutCreateWindow (argv
[0]);
167 glutReshapeFunc (reshape
);
168 glutKeyboardFunc (keyboard
);
169 glutDisplayFunc (display
);