OpenGLUT 0.6.3 development - OpenGLUT: tesswind.c File Reference
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# tesswind.c File Reference

## Detailed Description

This program demonstrates the winding rule polygon tessellation property. Four tessellated objects are drawn, each with very different contours. When the w key is pressed, the objects are drawn with a different winding rule.

    /*
     * 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     * Unpublished-- rights reserved under the copyright laws of the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.
     */

    #include <GL/openglut.h>
    #include <stdlib.h>
    #include <stdio.h>

    #ifdef GLU_VERSION_1_2

    /* Win32 calling conventions. */
    #ifndef CALLBACK
    #define CALLBACK
    #endif

    GLdouble currentWinding = GLU_TESS_WINDING_ODD;
    int currentShape = 0;
    GLUtesselator *tobj;
    GLuint list;

    /*  Make four display lists,
     *  each with a different tessellated object.
     */
    void makeNewLists (void) {
       int i;
       static GLdouble rects[12][3] =
          {{ 50.0,  50.0, 0.0}, {300.0,  50.0, 0.0},
           {300.0, 300.0, 0.0}, { 50.0, 300.0, 0.0},
           {100.0, 100.0, 0.0}, {250.0, 100.0, 0.0},
           {250.0, 250.0, 0.0}, {100.0, 250.0, 0.0},
           {150.0, 150.0, 0.0}, {200.0, 150.0, 0.0},
           {200.0, 200.0, 0.0}, {150.0, 200.0, 0.0}};
       static GLdouble spiral[16][3] =
          {{400.0, 250.0, 0.0}, {400.0,  50.0, 0.0},
           { 50.0,  50.0, 0.0}, { 50.0, 400.0, 0.0},
           {350.0, 400.0, 0.0}, {350.0, 100.0, 0.0},
           {100.0, 100.0, 0.0}, {100.0, 350.0, 0.0},
           {300.0, 350.0, 0.0}, {300.0, 150.0, 0.0},
           {150.0, 150.0, 0.0}, {150.0, 300.0, 0.0},
           {250.0, 300.0, 0.0}, {250.0, 200.0, 0.0},
           {200.0, 200.0, 0.0}, {200.0, 250.0, 0.0}};
       static GLdouble quad1[4][3] =
          {{ 50.0, 150.0, 0.0}, {350.0, 150.0, 0.0},
           {350.0, 200.0, 0.0}, { 50.0, 200.0, 0.0}};
       static GLdouble quad2[4][3] =
          {{100.0, 100.0, 0.0}, {300.0, 100.0, 0.0},
           {300.0, 350.0, 0.0}, {100.0, 350.0, 0.0}};
       static GLdouble tri[3][3] =
          {{200.0, 50.0, 0.0}, {250.0, 300.0, 0.0},
           {150.0, 300.0, 0.0}};

       gluTessProperty(tobj, GLU_TESS_WINDING_RULE,
                       currentWinding);

       glNewList(list, GL_COMPILE);
          gluTessBeginPolygon(tobj, NULL);
             gluTessBeginContour(tobj);
             for (i = 0; i < 4; i++)
                gluTessVertex(tobj, rects[i], rects[i]);
             gluTessEndContour(tobj);
             gluTessBeginContour(tobj);
             for (i = 4; i < 8; i++)
                gluTessVertex(tobj, rects[i], rects[i]);
             gluTessEndContour(tobj);
             gluTessBeginContour(tobj);
             for (i = 8; i < 12; i++)
                gluTessVertex(tobj, rects[i], rects[i]);
             gluTessEndContour(tobj);
          gluTessEndPolygon(tobj);
       glEndList();

       glNewList(list+1, GL_COMPILE);
          gluTessBeginPolygon(tobj, NULL);
             gluTessBeginContour(tobj);
             for (i = 0; i < 4; i++)
                gluTessVertex(tobj, rects[i], rects[i]);
             gluTessEndContour(tobj);
             gluTessBeginContour(tobj);
             for (i = 7; i >= 4; i--)
                gluTessVertex(tobj, rects[i], rects[i]);
             gluTessEndContour(tobj);
             gluTessBeginContour(tobj);
             for (i = 11; i >= 8; i--)
                gluTessVertex(tobj, rects[i], rects[i]);
             gluTessEndContour(tobj);
          gluTessEndPolygon(tobj);
       glEndList();

       glNewList(list+2, GL_COMPILE);
          gluTessBeginPolygon(tobj, NULL);
             gluTessBeginContour(tobj);
             for (i = 0; i < 16; i++)
                gluTessVertex(tobj, spiral[i], spiral[i]);
             gluTessEndContour(tobj);
          gluTessEndPolygon(tobj);
       glEndList();

       glNewList(list+3, GL_COMPILE);
          gluTessBeginPolygon(tobj, NULL);
             gluTessBeginContour(tobj);
             for (i = 0; i < 4; i++)
                gluTessVertex(tobj, quad1[i], quad1[i]);
             gluTessEndContour(tobj);
             gluTessBeginContour(tobj);
             for (i = 0; i < 4; i++)
                gluTessVertex(tobj, quad2[i], quad2[i]);
             gluTessEndContour(tobj);
             gluTessBeginContour(tobj);
             for (i = 0; i < 3; i++)
                gluTessVertex(tobj, tri[i], tri[i]);
             gluTessEndContour(tobj);
          gluTessEndPolygon(tobj);
       glEndList();
    }

    void display (void) {
       glClear(GL_COLOR_BUFFER_BIT);
       glColor3f(1.0, 1.0, 1.0);
       glPushMatrix();
       glCallList(list);
       glTranslatef(0.0, 500.0, 0.0);
       glCallList(list+1);
       glTranslatef(500.0, -500.0, 0.0);
       glCallList(list+2);
       glTranslatef(0.0, 500.0, 0.0);
       glCallList(list+3);
       glPopMatrix();
       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", (char *) estring);
       exit(0);
    }

    void CALLBACK endCallback(void)
    {
       glEnd();
    }

    /*  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.
     */
    /* ARGSUSED */
    void CALLBACK combineCallback(GLdouble coords[3], GLdouble *data[4],
                         GLfloat weight[4], GLdouble **dataOut )
    {
       GLdouble *vertex;
       vertex = (GLdouble *) malloc(3 * sizeof(GLdouble));

       vertex[0] = coords[0];
       vertex[1] = coords[1];
       vertex[2] = coords[2];
       *dataOut = vertex;
    }

    void init(void)
    {
       glClearColor(0.0, 0.0, 0.0, 0.0);
       glShadeModel(GL_FLAT);

       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);
       gluTessCallback(tobj, GLU_TESS_COMBINE,
                       (GLvoid (CALLBACK*) ()) &combineCallback);

       list = glGenLists(4);
       makeNewLists();
    }

    void reshape(int w, int h)
    {
       glViewport(0, 0, (GLsizei) w, (GLsizei) h);
       glMatrixMode(GL_PROJECTION);
       glLoadIdentity();
       if (w <= h)
          gluOrtho2D(0.0, 1000.0, 0.0, 1000.0 * (GLdouble)h/(GLdouble)w);
       else
          gluOrtho2D(0.0, 1000.0 * (GLdouble)w/(GLdouble)h, 0.0, 1000.0);
       glMatrixMode(GL_MODELVIEW);
       glLoadIdentity();
    }

    /* ARGSUSED1 */
    void keyboard(unsigned char key, int x, int y)
    {
       switch (key) {
          case 'w':
          case 'W':
             if (currentWinding == GLU_TESS_WINDING_ODD)
                currentWinding = GLU_TESS_WINDING_NONZERO;
             else if (currentWinding == GLU_TESS_WINDING_NONZERO)
                currentWinding = GLU_TESS_WINDING_POSITIVE;
             else if (currentWinding == GLU_TESS_WINDING_POSITIVE)
                currentWinding = GLU_TESS_WINDING_NEGATIVE;
             else if (currentWinding == GLU_TESS_WINDING_NEGATIVE)
                currentWinding = GLU_TESS_WINDING_ABS_GEQ_TWO;
             else if (currentWinding == GLU_TESS_WINDING_ABS_GEQ_TWO)
                currentWinding = GLU_TESS_WINDING_ODD;
             makeNewLists();
             glutPostRedisplay();
             break;
          case 27:
             exit(0);
             break;
          default:
             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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