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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+ * Unpublished-- rights reserved under the copyright laws of the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.
+ */
+
+/*
+ * tess.c
+ * This program demonstrates polygon tessellation.
+ * Two tesselated objects are drawn. The first is a
+ * rectangle with a triangular hole. The second is a
+ * smooth shaded, self-intersecting star.
+ *
+ * Note the exterior rectangle is drawn with its vertices
+ * in counter-clockwise order, but its interior clockwise.
+ * Note the combineCallback is needed for the self-intersecting
+ * star. Also note that removing the TessProperty for the
+ * star will make the interior unshaded (WINDING_ODD).
+ */
+#include <GL/glut.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifdef GLU_VERSION_1_2
+
+/* Win32 calling conventions. */
+#ifndef CALLBACK
+#define CALLBACK
+#endif
+
+GLuint startList;
+
+void display (void) {
+ glClear(GL_COLOR_BUFFER_BIT);
+ glColor3f(1.0, 1.0, 1.0);
+ glCallList(startList);
+ glCallList(startList + 1);
+ glFlush();
+}
+
+void CALLBACK beginCallback(GLenum which)
+{
+ glBegin(which);
+}
+
+void CALLBACK errorCallback(GLenum errorCode)
+{
+ const GLubyte *estring;
+
+ estring = gluErrorString(errorCode);
+ fprintf(stderr, "Tessellation Error: %s\n", estring);
+ exit(0);
+}
+
+void CALLBACK endCallback(void)
+{
+ glEnd();
+}
+
+void CALLBACK vertexCallback(GLvoid *vertex)
+{
+ const GLdouble *pointer;
+
+ pointer = (GLdouble *) vertex;
+ glColor3dv(pointer+3);
+ glVertex3dv(vertex);
+}
+
+/* combineCallback is used to create a new vertex when edges
+ * intersect. coordinate location is trivial to calculate,
+ * but weight[4] may be used to average color, normal, or texture
+ * coordinate data. In this program, color is weighted.
+ */
+void CALLBACK combineCallback(GLdouble coords[3],
+ GLdouble *vertex_data[4],
+ GLfloat weight[4], GLdouble **dataOut )
+{
+ GLdouble *vertex;
+ int i;
+
+ vertex = (GLdouble *) malloc(6 * sizeof(GLdouble));
+
+ vertex[0] = coords[0];
+ vertex[1] = coords[1];
+ vertex[2] = coords[2];
+ for (i = 3; i < 7; i++)
+ vertex[i] = weight[0] * vertex_data[0][i]
+ + weight[1] * vertex_data[1][i]
+ + weight[2] * vertex_data[2][i]
+ + weight[3] * vertex_data[3][i];
+ *dataOut = vertex;
+}
+
+void init (void)
+{
+ GLUtesselator *tobj;
+ GLdouble rect[4][3] = {50.0, 50.0, 0.0,
+ 200.0, 50.0, 0.0,
+ 200.0, 200.0, 0.0,
+ 50.0, 200.0, 0.0};
+ GLdouble tri[3][3] = {75.0, 75.0, 0.0,
+ 125.0, 175.0, 0.0,
+ 175.0, 75.0, 0.0};
+ GLdouble star[5][6] = {250.0, 50.0, 0.0, 1.0, 0.0, 1.0,
+ 325.0, 200.0, 0.0, 1.0, 1.0, 0.0,
+ 400.0, 50.0, 0.0, 0.0, 1.0, 1.0,
+ 250.0, 150.0, 0.0, 1.0, 0.0, 0.0,
+ 400.0, 150.0, 0.0, 0.0, 1.0, 0.0};
+
+ glClearColor(0.0, 0.0, 0.0, 0.0);
+
+ startList = glGenLists(2);
+
+ tobj = gluNewTess();
+ gluTessCallback(tobj, GLU_TESS_VERTEX,
+ (GLvoid (CALLBACK*) ()) &glVertex3dv);
+ gluTessCallback(tobj, GLU_TESS_BEGIN,
+ (GLvoid (CALLBACK*) ()) &beginCallback);
+ gluTessCallback(tobj, GLU_TESS_END,
+ (GLvoid (CALLBACK*) ()) &endCallback);
+ gluTessCallback(tobj, GLU_TESS_ERROR,
+ (GLvoid (CALLBACK*) ()) &errorCallback);
+
+ /* rectangle with triangular hole inside */
+ glNewList(startList, GL_COMPILE);
+ glShadeModel(GL_FLAT);
+ gluTessBeginPolygon(tobj, NULL);
+ gluTessBeginContour(tobj);
+ gluTessVertex(tobj, rect[0], rect[0]);
+ gluTessVertex(tobj, rect[1], rect[1]);
+ gluTessVertex(tobj, rect[2], rect[2]);
+ gluTessVertex(tobj, rect[3], rect[3]);
+ gluTessEndContour(tobj);
+ gluTessBeginContour(tobj);
+ gluTessVertex(tobj, tri[0], tri[0]);
+ gluTessVertex(tobj, tri[1], tri[1]);
+ gluTessVertex(tobj, tri[2], tri[2]);
+ gluTessEndContour(tobj);
+ gluTessEndPolygon(tobj);
+ glEndList();
+
+ gluTessCallback(tobj, GLU_TESS_VERTEX,
+ (GLvoid (CALLBACK*) ()) &vertexCallback);
+ gluTessCallback(tobj, GLU_TESS_BEGIN,
+ (GLvoid (CALLBACK*) ()) &beginCallback);
+ gluTessCallback(tobj, GLU_TESS_END,
+ (GLvoid (CALLBACK*) ()) &endCallback);
+ gluTessCallback(tobj, GLU_TESS_ERROR,
+ (GLvoid (CALLBACK*) ()) &errorCallback);
+ gluTessCallback(tobj, GLU_TESS_COMBINE,
+ (GLvoid (CALLBACK*) ()) &combineCallback);
+
+ /* smooth shaded, self-intersecting star */
+ glNewList(startList + 1, GL_COMPILE);
+ glShadeModel(GL_SMOOTH);
+ gluTessProperty(tobj, GLU_TESS_WINDING_RULE,
+ GLU_TESS_WINDING_POSITIVE);
+ gluTessBeginPolygon(tobj, NULL);
+ gluTessBeginContour(tobj);
+ gluTessVertex(tobj, star[0], star[0]);
+ gluTessVertex(tobj, star[1], star[1]);
+ gluTessVertex(tobj, star[2], star[2]);
+ gluTessVertex(tobj, star[3], star[3]);
+ gluTessVertex(tobj, star[4], star[4]);
+ gluTessEndContour(tobj);
+ gluTessEndPolygon(tobj);
+ glEndList();
+ gluDeleteTess(tobj);
+}
+
+void reshape (int w, int h)
+{
+ glViewport(0, 0, (GLsizei) w, (GLsizei) h);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h);
+}
+
+/* ARGSUSED1 */
+void keyboard(unsigned char key, int x, int y)
+{
+ switch (key) {
+ case 27:
+ exit(0);
+ break;
+ }
+}
+
+int main(int argc, char** argv)
+{
+ glutInit(&argc, argv);
+ glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
+ glutInitWindowSize(500, 500);
+ glutCreateWindow(argv[0]);
+ init();
+ glutDisplayFunc(display);
+ glutReshapeFunc(reshape);
+ glutKeyboardFunc(keyboard);
+ glutMainLoop();
+ return 0;
+}
+
+#else
+int main(int argc, char** argv)
+{
+ fprintf (stderr, "This program demonstrates the new tesselator API in GLU 1.2.\n");
+ fprintf (stderr, "Your GLU library does not support this new interface, sorry.\n");
+ return 0;
+}
+#endif
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