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diff --git a/progs/redbook/feedback.c b/progs/redbook/feedback.c
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+/*
+ * Copyright (c) 1993-1997, Silicon Graphics, Inc.
+ * ALL RIGHTS RESERVED
+ * Permission to use, copy, modify, and distribute this software for
+ * any purpose and without fee is hereby granted, provided that the above
+ * copyright notice appear in all copies and that both the copyright notice
+ * and this permission notice appear in supporting documentation, and that
+ * the name of Silicon Graphics, Inc. not be used in advertising
+ * or publicity pertaining to distribution of the software without specific,
+ * written prior permission.
+ *
+ * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
+ * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
+ * FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
+ * GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
+ * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
+ * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
+ * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
+ * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
+ * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
+ * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * US Government Users Restricted Rights
+ * Use, duplication, or disclosure by the Government is subject to
+ * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
+ * (c)(1)(ii) of the Rights in Technical Data and Computer Software
+ * clause at DFARS 252.227-7013 and/or in similar or successor
+ * clauses in the FAR or the DOD or NASA FAR Supplement.
+ * Unpublished-- rights reserved under the copyright laws of the
+ * United States. Contractor/manufacturer is Silicon Graphics,
+ * Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
+ *
+ * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
+ */
+
+/*
+ * feedback.c
+ * This program demonstrates use of OpenGL feedback. First,
+ * a lighting environment is set up and a few lines are drawn.
+ * Then feedback mode is entered, and the same lines are
+ * drawn. The results in the feedback buffer are printed.
+ */
+#include <GL/glut.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+/* Initialize lighting.
+ */
+void init(void)
+{
+ glEnable(GL_LIGHTING);
+ glEnable(GL_LIGHT0);
+}
+
+/* Draw a few lines and two points, one of which will
+ * be clipped. If in feedback mode, a passthrough token
+ * is issued between the each primitive.
+ */
+void drawGeometry (GLenum mode)
+{
+ glBegin (GL_LINE_STRIP);
+ glNormal3f (0.0, 0.0, 1.0);
+ glVertex3f (30.0, 30.0, 0.0);
+ glVertex3f (50.0, 60.0, 0.0);
+ glVertex3f (70.0, 40.0, 0.0);
+ glEnd ();
+ if (mode == GL_FEEDBACK)
+ glPassThrough (1.0);
+ glBegin (GL_POINTS);
+ glVertex3f (-100.0, -100.0, -100.0); /* will be clipped */
+ glEnd ();
+ if (mode == GL_FEEDBACK)
+ glPassThrough (2.0);
+ glBegin (GL_POINTS);
+ glNormal3f (0.0, 0.0, 1.0);
+ glVertex3f (50.0, 50.0, 0.0);
+ glEnd ();
+}
+
+/* Write contents of one vertex to stdout. */
+void print3DcolorVertex (GLint size, GLint *count,
+ GLfloat *buffer)
+{
+ int i;
+
+ printf (" ");
+ for (i = 0; i < 7; i++) {
+ printf ("%4.2f ", buffer[size-(*count)]);
+ *count = *count - 1;
+ }
+ printf ("\n");
+}
+
+/* Write contents of entire buffer. (Parse tokens!) */
+void printBuffer(GLint size, GLfloat *buffer)
+{
+ GLint count;
+ GLfloat token;
+
+ count = size;
+ while (count) {
+ token = buffer[size-count]; count--;
+ if (token == GL_PASS_THROUGH_TOKEN) {
+ printf ("GL_PASS_THROUGH_TOKEN\n");
+ printf (" %4.2f\n", buffer[size-count]);
+ count--;
+ }
+ else if (token == GL_POINT_TOKEN) {
+ printf ("GL_POINT_TOKEN\n");
+ print3DcolorVertex (size, &count, buffer);
+ }
+ else if (token == GL_LINE_TOKEN) {
+ printf ("GL_LINE_TOKEN\n");
+ print3DcolorVertex (size, &count, buffer);
+ print3DcolorVertex (size, &count, buffer);
+ }
+ else if (token == GL_LINE_RESET_TOKEN) {
+ printf ("GL_LINE_RESET_TOKEN\n");
+ print3DcolorVertex (size, &count, buffer);
+ print3DcolorVertex (size, &count, buffer);
+ }
+ }
+}
+
+void display(void)
+{
+ GLfloat feedBuffer[1024];
+ GLint size;
+
+ glMatrixMode (GL_PROJECTION);
+ glLoadIdentity ();
+ glOrtho (0.0, 100.0, 0.0, 100.0, 0.0, 1.0);
+
+ glClearColor (0.0, 0.0, 0.0, 0.0);
+ glClear(GL_COLOR_BUFFER_BIT);
+ drawGeometry (GL_RENDER);
+
+ glFeedbackBuffer (1024, GL_3D_COLOR, feedBuffer);
+ (void) glRenderMode (GL_FEEDBACK);
+ drawGeometry (GL_FEEDBACK);
+
+ size = glRenderMode (GL_RENDER);
+ printBuffer (size, feedBuffer);
+}
+
+/* ARGSUSED1 */
+void keyboard(unsigned char key, int x, int y)
+{
+ switch (key) {
+ case 27:
+ exit(0);
+ break;
+ }
+}
+
+/* Main Loop */
+int main(int argc, char** argv)
+{
+ glutInit(&argc, argv);
+ glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
+ glutInitWindowSize (100, 100);
+ glutInitWindowPosition (100, 100);
+ glutCreateWindow(argv[0]);
+ init();
+ glutDisplayFunc(display);
+ glutKeyboardFunc (keyboard);
+ glutMainLoop();
+ return 0;
+}