/* * 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 * Unpublished-- rights reserved under the copyright laws of the * United States.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); glFinish(); } /* 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; }