feedback.c revision 32001f49 
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31 * Unpublished-- rights reserved under the copyright laws of the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/*
39 * feedback.c
40 * This program demonstrates use of OpenGL feedback.  First,
41 * a lighting environment is set up and a few lines are drawn.
42 * Then feedback mode is entered, and the same lines are
43 * drawn.  The results in the feedback buffer are printed.
44 */
45#include "glut_wrap.h"
46#include <stdlib.h>
47#include <stdio.h>
48
49/*  Initialize lighting.
50 */
51static void init(void)
52{
53   glEnable(GL_LIGHTING);
54   glEnable(GL_LIGHT0);
55}
56
57/* Draw a few lines and two points, one of which will
58 * be clipped.  If in feedback mode, a passthrough token
59 * is issued between the each primitive.
60 */
61static void drawGeometry (GLenum mode)
62{
63   glBegin (GL_LINE_STRIP);
64   glNormal3f (0.0, 0.0, 1.0);
65   glVertex3f (30.0, 30.0, 0.0);
66   glVertex3f (50.0, 60.0, 0.0);
67   glVertex3f (70.0, 40.0, 0.0);
68   glEnd ();
69   if (mode == GL_FEEDBACK)
70      glPassThrough (1.0);
71   glBegin (GL_POINTS);
72   glVertex3f (-100.0, -100.0, -100.0);  /*  will be clipped  */
73   glEnd ();
74   if (mode == GL_FEEDBACK)
75      glPassThrough (2.0);
76   glBegin (GL_POINTS);
77   glNormal3f (0.0, 0.0, 1.0);
78   glVertex3f (50.0, 50.0, 0.0);
79   glEnd ();
80}
81
82/* Write contents of one vertex to stdout.	*/
83static void print3DcolorVertex (GLint size, GLint *count,
84                                GLfloat *buffer)
85{
86   int i;
87
88   printf ("  ");
89   for (i = 0; i < 7; i++) {
90      printf ("%4.2f ", buffer[size-(*count)]);
91      *count = *count - 1;
92   }
93   printf ("\n");
94}
95
96/*  Write contents of entire buffer.  (Parse tokens!)	*/
97static void printBuffer(GLint size, GLfloat *buffer)
98{
99   GLint count;
100   GLfloat token;
101
102   count = size;
103   while (count) {
104      token = buffer[size-count]; count--;
105      if (token == GL_PASS_THROUGH_TOKEN) {
106         printf ("GL_PASS_THROUGH_TOKEN\n");
107         printf ("  %4.2f\n", buffer[size-count]);
108         count--;
109      }
110      else if (token == GL_POINT_TOKEN) {
111         printf ("GL_POINT_TOKEN\n");
112         print3DcolorVertex (size, &count, buffer);
113      }
114      else if (token == GL_LINE_TOKEN) {
115         printf ("GL_LINE_TOKEN\n");
116         print3DcolorVertex (size, &count, buffer);
117         print3DcolorVertex (size, &count, buffer);
118      }
119      else if (token == GL_LINE_RESET_TOKEN) {
120         printf ("GL_LINE_RESET_TOKEN\n");
121         print3DcolorVertex (size, &count, buffer);
122         print3DcolorVertex (size, &count, buffer);
123      }
124   }
125}
126
127static void display(void)
128{
129   GLfloat feedBuffer[1024];
130   GLint size;
131
132   glMatrixMode (GL_PROJECTION);
133   glLoadIdentity ();
134   glOrtho (0.0, 100.0, 0.0, 100.0, 0.0, 1.0);
135
136   glClearColor (0.0, 0.0, 0.0, 0.0);
137   glClear(GL_COLOR_BUFFER_BIT);
138   drawGeometry (GL_RENDER);
139
140   glFeedbackBuffer (1024, GL_3D_COLOR, feedBuffer);
141   (void) glRenderMode (GL_FEEDBACK);
142   drawGeometry (GL_FEEDBACK);
143
144   size = glRenderMode (GL_RENDER);
145   printBuffer (size, feedBuffer);
146
147   glFinish();
148}
149
150/* ARGSUSED1 */
151static void keyboard(unsigned char key, int x, int y)
152{
153   switch (key) {
154      case 27:
155         exit(0);
156         break;
157   }
158}
159
160/*  Main Loop  */
161int main(int argc, char** argv)
162{
163   glutInit(&argc, argv);
164   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
165   glutInitWindowSize (100, 100);
166   glutInitWindowPosition (100, 100);
167   glutCreateWindow(argv[0]);
168   init();
169   glutDisplayFunc(display);
170   glutKeyboardFunc (keyboard);
171   glutMainLoop();
172   return 0;
173}
174