242 lines
7.8 KiB
C
242 lines
7.8 KiB
C
/*
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* Copyright (c) 1993-1997, Silicon Graphics, Inc.
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* ALL RIGHTS RESERVED
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* Permission to use, copy, modify, and distribute this software for
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* any purpose and without fee is hereby granted, provided that the above
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* copyright notice appear in all copies and that both the copyright notice
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* and this permission notice appear in supporting documentation, and that
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* the name of Silicon Graphics, Inc. not be used in advertising
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* or publicity pertaining to distribution of the software without specific,
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* written prior permission.
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*
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* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
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* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
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* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
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* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
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* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
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* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
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* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
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* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
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* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
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* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* US Government Users Restricted Rights
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* Use, duplication, or disclosure by the Government is subject to
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* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
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* (c)(1)(ii) of the Rights in Technical Data and Computer Software
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* clause at DFARS 252.227-7013 and/or in similar or successor
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* clauses in the FAR or the DOD or NASA FAR Supplement.
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* Unpublished-- rights reserved under the copyright laws of the
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* United States. Contractor/manufacturer is Silicon Graphics,
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* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
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*
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* OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
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*/
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/*
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* tess.c
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* This program demonstrates polygon tessellation.
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* Two tesselated objects are drawn. The first is a
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* rectangle with a triangular hole. The second is a
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* smooth shaded, self-intersecting star.
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*
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* Note the exterior rectangle is drawn with its vertices
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* in counter-clockwise order, but its interior clockwise.
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* Note the combineCallback is needed for the self-intersecting
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* star. Also note that removing the TessProperty for the
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* star will make the interior unshaded (WINDING_ODD).
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*/
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#include <GL/glut.h>
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#include <stdlib.h>
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#include <stdio.h>
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#ifdef GLU_VERSION_1_2
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/* Win32 calling conventions. */
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#ifndef CALLBACK
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#define CALLBACK
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#endif
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GLuint startList;
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void display (void) {
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glClear(GL_COLOR_BUFFER_BIT);
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glColor3f(1.0, 1.0, 1.0);
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glCallList(startList);
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glCallList(startList + 1);
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glFlush();
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}
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void CALLBACK beginCallback(GLenum which)
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{
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glBegin(which);
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}
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void CALLBACK errorCallback(GLenum errorCode)
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{
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const GLubyte *estring;
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estring = gluErrorString(errorCode);
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fprintf(stderr, "Tessellation Error: %s\n", (char *) estring);
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exit(0);
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}
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void CALLBACK endCallback(void)
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{
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glEnd();
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}
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void CALLBACK vertexCallback(GLvoid *vertex)
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{
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const GLdouble *pointer;
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pointer = (GLdouble *) vertex;
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glColor3dv(pointer+3);
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glVertex3dv(pointer);
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}
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/* combineCallback is used to create a new vertex when edges
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* intersect. coordinate location is trivial to calculate,
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* but weight[4] may be used to average color, normal, or texture
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* coordinate data. In this program, color is weighted.
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*/
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void CALLBACK combineCallback(GLdouble coords[3],
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GLdouble *vertex_data[4],
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GLfloat weight[4], GLdouble **dataOut )
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{
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GLdouble *vertex;
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int i;
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vertex = (GLdouble *) malloc(6 * sizeof(GLdouble));
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vertex[0] = coords[0];
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vertex[1] = coords[1];
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vertex[2] = coords[2];
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for (i = 3; i < 6; i++)
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vertex[i] = weight[0] * vertex_data[0][i]
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+ weight[1] * vertex_data[1][i]
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+ weight[2] * vertex_data[2][i]
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+ weight[3] * vertex_data[3][i];
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*dataOut = vertex;
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}
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void init (void)
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{
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GLUtesselator *tobj;
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GLdouble rect[4][3] = {{50.0, 50.0, 0.0},
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{200.0, 50.0, 0.0},
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{200.0, 200.0, 0.0},
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{50.0, 200.0, 0.0}};
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GLdouble tri[3][3] = {{75.0, 75.0, 0.0},
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{125.0, 175.0, 0.0},
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{175.0, 75.0, 0.0}};
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GLdouble star[5][6] = {{250.0, 50.0, 0.0, 1.0, 0.0, 1.0},
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{325.0, 200.0, 0.0, 1.0, 1.0, 0.0},
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{400.0, 50.0, 0.0, 0.0, 1.0, 1.0},
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{250.0, 150.0, 0.0, 1.0, 0.0, 0.0},
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{400.0, 150.0, 0.0, 0.0, 1.0, 0.0}};
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glClearColor(0.0, 0.0, 0.0, 0.0);
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startList = glGenLists(2);
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tobj = gluNewTess();
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gluTessCallback(tobj, GLU_TESS_VERTEX,
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(GLvoid (CALLBACK*) ()) &glVertex3dv);
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gluTessCallback(tobj, GLU_TESS_BEGIN,
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(GLvoid (CALLBACK*) ()) &beginCallback);
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gluTessCallback(tobj, GLU_TESS_END,
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(GLvoid (CALLBACK*) ()) &endCallback);
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gluTessCallback(tobj, GLU_TESS_ERROR,
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(GLvoid (CALLBACK*) ()) &errorCallback);
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/* rectangle with triangular hole inside */
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glNewList(startList, GL_COMPILE);
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glShadeModel(GL_FLAT);
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gluTessBeginPolygon(tobj, NULL);
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gluTessBeginContour(tobj);
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gluTessVertex(tobj, rect[0], rect[0]);
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gluTessVertex(tobj, rect[1], rect[1]);
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gluTessVertex(tobj, rect[2], rect[2]);
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gluTessVertex(tobj, rect[3], rect[3]);
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gluTessEndContour(tobj);
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gluTessBeginContour(tobj);
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gluTessVertex(tobj, tri[0], tri[0]);
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gluTessVertex(tobj, tri[1], tri[1]);
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gluTessVertex(tobj, tri[2], tri[2]);
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gluTessEndContour(tobj);
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gluTessEndPolygon(tobj);
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glEndList();
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gluTessCallback(tobj, GLU_TESS_VERTEX,
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(GLvoid (CALLBACK*) ()) &vertexCallback);
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gluTessCallback(tobj, GLU_TESS_BEGIN,
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(GLvoid (CALLBACK*) ()) &beginCallback);
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gluTessCallback(tobj, GLU_TESS_END,
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(GLvoid (CALLBACK*) ()) &endCallback);
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gluTessCallback(tobj, GLU_TESS_ERROR,
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(GLvoid (CALLBACK*) ()) &errorCallback);
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gluTessCallback(tobj, GLU_TESS_COMBINE,
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(GLvoid (CALLBACK*) ()) &combineCallback);
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/* smooth shaded, self-intersecting star */
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glNewList(startList + 1, GL_COMPILE);
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glShadeModel(GL_SMOOTH);
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gluTessProperty(tobj, GLU_TESS_WINDING_RULE,
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GLU_TESS_WINDING_POSITIVE);
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gluTessBeginPolygon(tobj, NULL);
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gluTessBeginContour(tobj);
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gluTessVertex(tobj, star[0], star[0]);
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gluTessVertex(tobj, star[1], star[1]);
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gluTessVertex(tobj, star[2], star[2]);
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gluTessVertex(tobj, star[3], star[3]);
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gluTessVertex(tobj, star[4], star[4]);
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gluTessEndContour(tobj);
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gluTessEndPolygon(tobj);
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glEndList();
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gluDeleteTess(tobj);
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}
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void reshape (int w, int h)
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{
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glViewport(0, 0, (GLsizei) w, (GLsizei) h);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h);
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}
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/* ARGSUSED1 */
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void keyboard(unsigned char key, int x, int y)
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{
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switch (key) {
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case 27:
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exit(0);
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break;
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}
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}
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int main(int argc, char** argv)
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{
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glutInit(&argc, argv);
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glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
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glutInitWindowSize(500, 500);
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glutCreateWindow(argv[0]);
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init();
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glutDisplayFunc(display);
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glutReshapeFunc(reshape);
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glutKeyboardFunc(keyboard);
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glutMainLoop();
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return 0;
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}
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#else
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int main(int argc, char** argv)
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{
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fprintf (stderr, "This program demonstrates the new tesselator API in GLU 1.2.\n");
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fprintf (stderr, "Your GLU library does not support this new interface, sorry.\n");
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return 0;
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}
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#endif
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