Function computeTrianglesFromCycles

src/Gui/VectorAnimationComplex/KeyFace.cpp:249–314

}

void computeTrianglesFromCycles(const QList<Cycle> & cycles, Triangles & triangles)
{

    // Creating polygon data for GLU tesselator
    PolygonData vertices = createPolygonData(cycles);

    // Creating the GLU tesselation object
    if(!tobjOffline)
    {
        tobjOffline = gluNewTess();
    }
    if(tobj != tobjOffline)
    {
        tobj = tobjOffline;

        gluTessCallback(tobj, GLU_TESS_VERTEX,
                        (GLvoid (CALLBACK*) ()) &offlineTessVertex);
        gluTessCallback(tobj, GLU_TESS_BEGIN,
                        (GLvoid (CALLBACK*) ()) &offlineTessBegin);
        gluTessCallback(tobj, GLU_TESS_END,
                        (GLvoid (CALLBACK*) ()) &offlineTessEnd);
        gluTessCallback(tobj, GLU_TESS_ERROR,
                        (GLvoid (CALLBACK*) ()) &offlineTessError);
        gluTessCallback(tobj, GLU_TESS_COMBINE,
                        (GLvoid (CALLBACK*) ()) &offlineTessCombine);
    }

    // Using the tesselation object
    gluTessProperty(tobj, GLU_TESS_WINDING_RULE, GLU_TESS_WINDING_ODD);

    // Specifying data
    offlineTessTriangles.clear();
    gluTessBeginPolygon(tobj, NULL);
    {
        for(auto & vec: vertices) // for each cycle
        {
            gluTessBeginContour(tobj); // draw a contour
            {
                for(auto & v: vec) // for each vertex in cycle
                {
                    // safeguard against NaN and other oddities
                    const double MAX_VALUE = 10000;
                    const double MIN_VALUE = -10000;
                    if( v[0] > MIN_VALUE &&
                        v[0] < MAX_VALUE &&
                        v[1] > MIN_VALUE &&
                        v[1] < MAX_VALUE &&
                        v[2] > MIN_VALUE &&
                        v[2] < MAX_VALUE )
                    {
                        gluTessVertex(tobj, v.data(), v.data()); // send vertex
                    }
                    else
                    {
                        qDebug() << "ignored vertex" << v[0]  << v[1]  << v[2] << "for tesselation";
                    }
                }
            }