Function edgeColoringInkTrap

MyGUIEngine/src/msdfgen/core/edge-coloring.cpp:151–258

};

void edgeColoringInkTrap(Shape &shape, double angleThreshold, unsigned long long seed) {
    typedef EdgeColoringInkTrapCorner Corner;
    double crossThreshold = sin(angleThreshold);
    EdgeColor color = initColor(seed);
    std::vector<Corner> corners;
    for (std::vector<Contour>::iterator contour = shape.contours.begin(); contour != shape.contours.end(); ++contour) {
        if (contour->edges.empty())
            continue;
        double splineLength = 0;
        { // Identify corners
            corners.clear();
            Vector2 prevDirection = contour->edges.back()->direction(1);
            int index = 0;
            for (std::vector<EdgeHolder>::const_iterator edge = contour->edges.begin(); edge != contour->edges.end(); ++edge, ++index) {
                if (isCorner(prevDirection.normalize(), (*edge)->direction(0).normalize(), crossThreshold)) {
                    Corner corner = { index, splineLength };
                    corners.push_back(corner);
                    splineLength = 0;
                }
                splineLength += estimateEdgeLength(*edge);
                prevDirection = (*edge)->direction(1);
            }
        }

        // Smooth contour
        if (corners.empty()) {
            switchColor(color, seed);
            for (std::vector<EdgeHolder>::iterator edge = contour->edges.begin(); edge != contour->edges.end(); ++edge)
                (*edge)->color = color;
        }
        // "Teardrop" case
        else if (corners.size() == 1) {
            EdgeColor colors[3];
            switchColor(color, seed);
            colors[0] = color;
            colors[1] = WHITE;
            switchColor(color, seed);
            colors[2] = color;
            int corner = corners[0].index;
            if (contour->edges.size() >= 3) {
                int m = (int) contour->edges.size();
                for (int i = 0; i < m; ++i)
                    contour->edges[(corner+i)%m]->color = colors[1+symmetricalTrichotomy(i, m)];
            } else if (contour->edges.size() >= 1) {
                // Less than three edge segments for three colors => edges must be split
                EdgeSegment *parts[7] = { };
                contour->edges[0]->splitInThirds(parts[0+3*corner], parts[1+3*corner], parts[2+3*corner]);
                if (contour->edges.size() >= 2) {
                    contour->edges[1]->splitInThirds(parts[3-3*corner], parts[4-3*corner], parts[5-3*corner]);
                    parts[0]->color = parts[1]->color = colors[0];
                    parts[2]->color = parts[3]->color = colors[1];
                    parts[4]->color = parts[5]->color = colors[2];
                } else {
                    parts[0]->color = colors[0];
                    parts[1]->color = colors[1];
                    parts[2]->color = colors[2];
                }
                contour->edges.clear();