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31 * Unpublished-- rights reserved under the copyright laws of the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
42static int leftFirst = GL_TRUE;
43
44static 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
58static int curFunc = 0;
59static double clearVal = 1.0;
60static float minZ = 0.0;
61static float maxZ = 1.0;
62
63static 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
76static void init(void)
77{
78   glEnable(GL_DEPTH_TEST);
79   glClearColor (1.0, 0.0, 0.0, 0.0);
80}
81
82static 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
93static 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
104static 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
127static 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 */
139static 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 */
191int 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