1 /*
2 * Copyright (c) 1993-1997, Silicon Graphics, Inc.
3 * ALL RIGHTS RESERVED
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.
11 *
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.
24 *
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31 * Unpublished-- rights reserved under the copyright laws of the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.
34 *
35 * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
36 */
37
38 #include "glut_wrap.h"
39 #include <stdlib.h>
40 #include <stdio.h>
41
42 static int leftFirst = GL_TRUE;
43
44 static struct { GLenum func; const char *str; } funcs[] =
45 {
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" },
54 };
55
56 #define NUM_FUNCS (sizeof(funcs) / sizeof(funcs[0]))
57
58 static int curFunc = 0;
59 static double clearVal = 1.0;
60 static float minZ = 0.0;
61 static float maxZ = 1.0;
62
usage(void)63 static void usage(void)
64 {
65 printf("t - toggle rendering order of triangles\n");
66 printf("c - toggle Z clear value between 0, 1\n");
67 printf("f - cycle through depth test functions\n");
68 printf("n/N - decrease/increase depthrange minZ\n");
69 printf("x/X - decrease/increase depthrange maxZ\n");
70 printf("spc - reset\n");
71 printf("z - set to reverse-direction (ztrick) mode\n");
72 fflush(stdout);
73 }
74
75
init(void)76 static void init(void)
77 {
78 glEnable(GL_DEPTH_TEST);
79 glClearColor (1.0, 0.0, 0.0, 0.0);
80 }
81
drawLeftTriangle(void)82 static void drawLeftTriangle(void)
83 {
84 /* draw yellow triangle on LHS of screen */
85 glBegin (GL_TRIANGLES);
86 glColor4f(1.0, 1.0, 0.0, 0.75);
87 glVertex3f(0.1, 0.9, -1.0);
88 glVertex3f(0.1, 0.1, -1.0);
89 glVertex3f(0.8, 0.5, 1.0);
90 glEnd();
91 }
92
drawRightTriangle(void)93 static void drawRightTriangle(void)
94 {
95 /* draw cyan triangle on RHS of screen */
96 glBegin (GL_TRIANGLES);
97 glColor4f(0.0, 1.0, 1.0, 0.75);
98 glVertex3f(0.9, 0.9, 0.0);
99 glVertex3f(0.2, 0.5, 0.0);
100 glVertex3f(0.9, 0.1, 0.0);
101 glEnd();
102 }
103
display(void)104 static void display(void)
105 {
106 printf("GL_CLEAR_DEPTH = %.2f, GL_DEPTH_FUNC = %s, DepthRange(%.1f, %.1f)\n",
107 clearVal, funcs[curFunc].str, minZ, maxZ);
108 fflush(stdout);
109 glClearDepth(clearVal);
110 glDepthRange(minZ, maxZ);
111 glDepthFunc(funcs[curFunc].func);
112
113 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
114
115 if (leftFirst) {
116 drawLeftTriangle();
117 drawRightTriangle();
118 }
119 else {
120 drawRightTriangle();
121 drawLeftTriangle();
122 }
123
124 glFlush();
125 }
126
reshape(int w,int h)127 static void reshape(int w, int h)
128 {
129 glViewport(0, 0, (GLsizei) w, (GLsizei) h);
130 glMatrixMode(GL_PROJECTION);
131 glLoadIdentity();
132 if (w <= h)
133 gluOrtho2D (0.0, 1.0, 0.0, 1.0*(GLfloat)h/(GLfloat)w);
134 else
135 gluOrtho2D (0.0, 1.0*(GLfloat)w/(GLfloat)h, 0.0, 1.0);
136 }
137
138 /* ARGSUSED1 */
keyboard(unsigned char key,int x,int y)139 static void keyboard(unsigned char key, int x, int y)
140 {
141 switch (key) {
142 case 'n':
143 minZ -= .1;
144 break;
145 case 'N':
146 minZ += .1;
147 break;
148 case 'x':
149 maxZ -= .1;
150 break;
151 case 'X':
152 maxZ += .1;
153 break;
154 case 'c':
155 case 'C':
156 clearVal = 1.0 - clearVal;
157 break;
158 case 'f':
159 case 'F':
160 curFunc = (curFunc + 1) % NUM_FUNCS;
161 break;
162 case 't':
163 case 'T':
164 leftFirst = !leftFirst;
165 break;
166 case ' ':
167 curFunc = 0;
168 clearVal = 1.0;
169 minZ = 0.0;
170 maxZ = 1.0;
171 break;
172 case 'z':
173 curFunc = 2;
174 clearVal = 0.0;
175 minZ = 1.0;
176 maxZ = 0.0;
177 break;
178 case 27: /* Escape key */
179 exit(0);
180 break;
181 default:
182 return;
183 }
184 glutPostRedisplay();
185 }
186
187 /* Main Loop
188 * Open window with initial window size, title bar,
189 * RGBA display mode, and handle input events.
190 */
main(int argc,char ** argv)191 int main(int argc, char** argv)
192 {
193 glutInit(&argc, argv);
194 glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
195 glutInitWindowSize (200, 200);
196 glutCreateWindow (argv[0]);
197 glutReshapeFunc (reshape);
198 glutKeyboardFunc (keyboard);
199 glutDisplayFunc (display);
200 init();
201 usage();
202 glutMainLoop();
203 return 0;
204 }
205