Exception occurred while drawing and filling polygons

[wangningyu]

osgEarth Version (required): 3.8.0

Description of the problem: Polygon filling anomaly

What you have tried: I have tried three methods to fill the semi transparent space

Under the 2D plan view (-180/90 in the lower left and right corners, 180/90 in the upper right corner), the following effect should be drawn:

I have encountered an issue where the semi transparent color filling is abnormal when drawing polygons.

I have tried the following three methods:

• 1.the default method

void OSGWidget::addLargeConcavePolygonBase(osgEarth::MapNode* mapNode)
{
    QPolygonF               qPoly;
    std::vector<osg::Vec3d> ctrlPoints;

    ctrlPoints.push_back(osg::Vec3d(90.0,  30.0, 0));
    ctrlPoints.push_back(osg::Vec3d(120.0,  13.0, 0));
    ctrlPoints.push_back(osg::Vec3d(140.0,  1.0, 0));
    ctrlPoints.push_back(osg::Vec3d(95.0,  -4.0, 0));
    ctrlPoints.push_back(osg::Vec3d(85.0,  -5.0, 0));
    ctrlPoints.push_back(osg::Vec3d(75.0,  -6.0, 0));
    ctrlPoints.push_back(osg::Vec3d(45.0,  -7.0, 0));
    ctrlPoints.push_back(osg::Vec3d(15.0,  -10.0, 0));
    ctrlPoints.push_back(osg::Vec3d(0.0,  -8.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-8.0,  -20.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-15.0,  -45.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-90.0,  -70.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-135.0,  -45.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-160.0,  -0.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-90.0,  28.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-5.0,  6.0, 0));

    for (size_t i = 0; i < ctrlPoints.size() - 1; ++i)
        qPoly.push_back(QPointF(ctrlPoints.at(i).x(), ctrlPoints.at(i).y()));

    static osg::observer_ptr<osg::Group> m_polygonGroup;
    if (m_polygonGroup.valid()) m_root->removeChild(m_polygonGroup.get());

    osg::ref_ptr<osg::Group> newGroup = new osg::Group();
    m_root->addChild(newGroup.get());
    m_polygonGroup = newGroup.get();

    const osgEarth::SpatialReference    *srs = mapNode->getMap()->getSRS();
    osgEarth::Style                     style;

    style.getOrCreate<osgEarth::PolygonSymbol>()->fill()->color() = osgEarth::Color(osg::Vec4(1.0, 0.65, 0.0, 0.4));
    //style.getOrCreate<osgEarth::LineSymbol>()->stroke()->color() = osgEarth::Color(osg::Vec4(1.0, 0.65, 0.0, 0.4));
    //style.getOrCreate<osgEarth::LineSymbol>()->stroke()->width() = osgEarth::Distance(0.001, osgEarth::Units::PIXELS);
    //style.getOrCreate<osgEarth::LineSymbol>()->tessellationSize() = osgEarth::Distance(1000, osgEarth::Units::METERS);

    osgEarth::AltitudeSymbol* as = style.getOrCreate<osgEarth::AltitudeSymbol>();
    as->clamping() = osgEarth::AltitudeSymbol::CLAMP_RELATIVE_TO_TERRAIN;
    as->technique() = osgEarth::AltitudeSymbol::TECHNIQUE_DRAPE;
    as->verticalOffset() = osgEarth::Distance(0.5, osgEarth::Units::METERS);

    osg::ref_ptr<osgEarth::Polygon> poly = new osgEarth::Polygon();
    for (const QPointF& pt : qPoly)
    {
        poly->push_back(osg::Vec3d(pt.x(), pt.y(), 0.0));
    }

    if (poly->front() != poly->back())
        poly->push_back(poly->front());

    poly->rewind(osgEarth::Geometry::ORIENTATION_CCW);

    osg::ref_ptr<osgEarth::FeatureNode> fn = new osgEarth::FeatureNode(new osgEarth::Feature(poly.get(), srs, style));
    fn->getOrCreateStateSet()->setRenderBinDetails(10, "RenderBin");
    newGroup->addChild(fn.get());
}

this type can't show any polygon and fill color

• 2. use TessellateOperator::tessellateGeo

// Using TessellateOperator to segment and draw functions
void OSGWidget::addLargeConcavePolygonTess(osgEarth::MapNode* mapNode)
{
    std::vector<osg::Vec3d> ctrlPoints;

    ctrlPoints.push_back(osg::Vec3d(90.0,  30.0, 0));
    ctrlPoints.push_back(osg::Vec3d(120.0,  13.0, 0));
    ctrlPoints.push_back(osg::Vec3d(140.0,  1.0, 0));
    ctrlPoints.push_back(osg::Vec3d(95.0,  -4.0, 0));
    ctrlPoints.push_back(osg::Vec3d(85.0,  -5.0, 0));
    ctrlPoints.push_back(osg::Vec3d(75.0,  -6.0, 0));
    ctrlPoints.push_back(osg::Vec3d(45.0,  -7.0, 0));
    ctrlPoints.push_back(osg::Vec3d(15.0,  -10.0, 0));
    ctrlPoints.push_back(osg::Vec3d(0.0,  -8.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-8.0,  -20.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-15.0,  -45.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-90.0,  -70.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-135.0,  -45.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-160.0,  -0.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-90.0,  28.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-5.0,  6.0, 0));

    osg::ref_ptr<osgEarth::Polygon> finalPoly = new osgEarth::Polygon();
    int numPoints = ctrlPoints.size();

    for (int i = 0; i < numPoints; ++i)
    {
        std::vector<osg::Vec3d> segmentPoints;

        // Calculate the index of the next point, and if it reaches the end, take the remainder to return to 0
        int nextIdx = (i + 1) % numPoints;

        // Split the long side into multiple segments
        osgEarth::Util::TessellateOperator::tessellateGeo(
            ctrlPoints[i],
            ctrlPoints[nextIdx],
            100,
            osgEarth::GEOINTERP_GREAT_CIRCLE, // Interpolation of large circular flight path
            segmentPoints
            );

        // Discard the last point of each paragraph
        // This not only avoids repeating the beginning and end, but also perfectly closes the entire polygon
        for (size_t j = 0; j < segmentPoints.size() - 1; ++j) {
            finalPoly->push_back(segmentPoints[j]);
        }
    }

    osg::ref_ptr<osgEarth::Feature> feature = new osgEarth::Feature(finalPoly.get(), osgEarth::SpatialReference::get("wgs84"));
    osgEarth::Style style;

    osgEarth::PolygonSymbol* fill = style.getOrCreate<osgEarth::PolygonSymbol>();
    fill->fill()->color() = osgEarth::Color(osgEarth::Color::Red, 0.5);

    osgEarth::LineSymbol* ls = style.getOrCreate<osgEarth::LineSymbol>();
    ls->stroke()->color() = osgEarth::Color::Green;
    ls->stroke()->width() = osgEarth::Distance(1.0, osgEarth::Units::PIXELS);

    osgEarth::AltitudeSymbol* alt = style.getOrCreate<osgEarth::AltitudeSymbol>();
    alt->clamping() = osgEarth::AltitudeSymbol::CLAMP_TO_TERRAIN;
    alt->technique() = osgEarth::AltitudeSymbol::TECHNIQUE_DRAPE;//TECHNIQUE_GPU;
    feature->setStyle(style);

    osg::ref_ptr<osgEarth::FeatureNode> node = new osgEarth::FeatureNode(feature.get());
    node->setMapNode(mapNode);

    mapNode->addChild(node.get());
}

TessellateOperator's type can show the green bordline, but fill failed.

• 3. split the East and West Hemispheres

// Forcefully insert a necessary point passing through the Y-axis in a polygon
QPolygonF insertYAxisIntersections(const QPolygonF& poly)
{
    QPolygonF newPoly;
    int n = poly.size();
    if (n < 2) return poly;

    for (int i = 0; i < n; ++i)
    {
        const QPointF& p1 = poly[i];
        const QPointF& p2 = poly[(i+1) % n]; // Next points, wrap around the polygon

        newPoly.push_back(p1); // First add the current point

        // Determine whether two points span both sides (x < 0 and x > 0)
        if ((p1.x() < 0 && p2.x() > 0) || (p1.x() > 0 && p2.x() < 0))
        {
            double t = (0.0 - p1.x()) / (p2.x() - p1.x()); // linear interpolation
            double yIntersect = p1.y() + t * (p2.y() - p1.y());
            QPointF interPoint(0.0, yIntersect);

            newPoly.push_back(interPoint); // Insert Intersection Point
        }
    }

    return newPoly;
}

void OSGWidget::addLargeConcavePolygonEastWest(osgEarth::MapNode* mapNode)
{
    QPolygonF               qPoly;
    std::vector<osg::Vec3d> ctrlPoints;

    ctrlPoints.push_back(osg::Vec3d(90.0,  30.0, 0));
    ctrlPoints.push_back(osg::Vec3d(120.0,  13.0, 0));
    ctrlPoints.push_back(osg::Vec3d(140.0,  1.0, 0));
    ctrlPoints.push_back(osg::Vec3d(95.0,  -4.0, 0));
    ctrlPoints.push_back(osg::Vec3d(85.0,  -5.0, 0));
    ctrlPoints.push_back(osg::Vec3d(75.0,  -6.0, 0));
    ctrlPoints.push_back(osg::Vec3d(45.0,  -7.0, 0));
    ctrlPoints.push_back(osg::Vec3d(15.0,  -10.0, 0));
    ctrlPoints.push_back(osg::Vec3d(0.0,  -8.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-8.0,  -20.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-15.0,  -45.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-90.0,  -70.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-135.0,  -45.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-160.0,  -0.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-90.0,  28.0, 0));
    ctrlPoints.push_back(osg::Vec3d(-5.0,  6.0, 0));

    for (size_t i = 0; i < ctrlPoints.size() - 1; ++i)
        qPoly.push_back(QPointF(ctrlPoints.at(i).x(), ctrlPoints.at(i).y()));

    // If two points of the original shape pass through the Y-axis, insert a point that passes through the Y-axis
    QPolygonF                           modifiedPoly = insertYAxisIntersections(qPoly);
    osg::ref_ptr<osg::Group>            newGroup = new osg::Group();
    mapNode->addChild(newGroup.get());

    const osgEarth::SpatialReference* srs = mapNode->getMap()->getSRS();

    osgEarth::Style style;
    style.getOrCreate<osgEarth::PolygonSymbol>()->fill()->color() = osgEarth::Color(osg::Vec4(1.0, 0.65, 0.0, 0.4));

    style.getOrCreate<osgEarth::LineSymbol>()->tessellationSize() = osgEarth::Distance(500, osgEarth::Units::METERS);
    style.getOrCreate<osgEarth::LineSymbol>()->stroke()->color() = osgEarth::Color(osg::Vec4(1.0, 0.65, 0.0, 0.4));
    style.getOrCreate<osgEarth::LineSymbol>()->stroke()->width() = osgEarth::Distance(0.01, osgEarth::Units::METERS);

    osgEarth::AltitudeSymbol* as = style.getOrCreate<osgEarth::AltitudeSymbol>();
    as->clamping() = osgEarth::AltitudeSymbol::CLAMP_RELATIVE_TO_TERRAIN;
    as->technique() = osgEarth::AltitudeSymbol::TECHNIQUE_DRAPE;
    as->verticalOffset() = osgEarth::Distance(0.5, osgEarth::Units::METERS);

    // Draw separately from the east and west hemispheres
    osg::ref_ptr<osgEarth::Polygon> westPoly = new osgEarth::Polygon();
    osg::ref_ptr<osgEarth::Polygon> eastPoly = new osgEarth::Polygon();

    for (const QPointF& pt : modifiedPoly) {
        double lon = pt.x();
        if (lon <= 0) westPoly->push_back(osg::Vec3d(lon, pt.y(), 0));
        if (lon >= 0) eastPoly->push_back(osg::Vec3d(lon, pt.y(), 0));
    }

    // Process polygons of two hemispheres separately
    auto processSubPoly = [&](osg::ref_ptr<osgEarth::Polygon> sub) {
        if (sub->size() < 3) return;
        sub->rewind(osgEarth::Geometry::ORIENTATION_CCW);
        osg::ref_ptr<osgEarth::FeatureNode> fn = new osgEarth::FeatureNode(new osgEarth::Feature(sub.get(), srs, style));
        fn->getOrCreateStateSet()->setRenderBinDetails(10, "RenderBin");
        newGroup->addChild(fn.get());
    };

    if(westPoly->size()) processSubPoly(westPoly);
    if(eastPoly->size()) processSubPoly(eastPoly);
}

If the border lines of the segmented polygon are colored, there will be a vertical line in the middle.

At present, I am not sure if this is due to an error in my usage method or a rendering error myself?

Best Regards!

[gwaldron]

What are you trying to do that requires these huge world-spanning polygons?
Or are you just testing the limits of the software?

Anyway, you might have better luck with a FeatureImageLayer instead of a draped FeatureNode.

<FeatureImage name="Large polygon">
    <OGRFeatures name="geometry">
        <geometry>
            POLYGON ((  90 30,  120 13,  140 1,  95 -4,  85 -5,  75 -6,  45 -7,  15 -10,  0 -8,  -8 -20,  -15 -45,  -90 -70,  -135 -45,  -160 0,  -90 28,  -5 6,  90 30))
        </geometry>
    </OGRFeatures>
    <styles>
        <style type="text/css">
            default {
               fill: #ffff006f;
               stroke: #ffff00;
               stroke-width: 1px;
            }                    
        </style>
    </styles>        
</FeatureImage>

[wangningyu]

than you! I will try this way later.

the sources of these polygon data are:
A numerical value (signal strength) obtained by calculating the global area of 360 * 180 using a wireless communication algorithm, similar to this:
double fVal[5][5] = {....};
Reuse bilinear interpolation to obtain
double fVal[360][720] = {....};
Then use GDAL to extract this data and use GDALContourGenerate to generate contour polygons, similar to this software:

this is the old shape:

use easet and west to draw on osgearth:

this is the old 5*5 data: (lat, lng, MUF)
REC533 Version 16.1207A
TANGIER, Morocco [HR 4/4/.5 ] 500kW 57deg 18ut 11.850MHz JUN 100ssn
5 5 Latitude Longitude MUF MODE ANGL DBU S/N FS/N SNxx
1 1 -90.0000 -180.0000 10.17 --- 3.0 -0.7 34.4 0.010 13.7
2 1 -90.0000 -90.0000 10.17 --- 3.0 -0.7 34.4 0.010 13.7
3 1 -90.0000 0.0000 10.17 --- 3.0 -0.7 34.4 0.010 13.7
4 1 -90.0000 90.0000 10.17 --- 3.0 -0.7 34.4 0.010 13.7
5 1 -90.0000 180.0000 10.17 --- 3.0 -0.7 34.4 0.010 13.7
1 2 -45.0000 -180.0000 10.73 --- 3.0 -8.8 25.8 0.010 8.4
2 2 -45.0000 -90.0000 34.99 --- 3.0 -44.8 -11.1 0.010 -25.2
3 2 -45.0000 0.0000 21.74 --- 3.0 16.8 49.6 0.010 35.7
4 2 -45.0000 90.0000 9.29 --- 3.0 3.8 38.9 0.010 21.4
5 2 -45.0000 180.0000 10.73 --- 3.0 -8.8 25.8 0.010 8.4
1 3 0.0000 -180.0000 22.68 --- 3.0 -41.2 -7.7 0.010 -23.5
2 3 0.0000 -90.0000 28.70 --- 3.0 -36.1 -1.3 0.010 -15.6
3 3 0.0000 0.0000 24.55 3F2 15.0 30.6 63.8 0.107 49.6
4 3 0.0000 90.0000 25.86 --- 3.0 32.6 65.0 0.119 51.6
5 3 0.0000 180.0000 22.68 --- 3.0 -41.2 -7.7 0.010 -23.5
1 4 45.0000 -180.0000 19.18 --- 3.0 -16.7 18.0 0.010 2.0
2 4 45.0000 -90.0000 20.91 4F2 22.0 1.6 37.1 0.010 20.9
3 4 45.0000 0.0000 13.53 1E 8.0 49.7 82.6 0.791 65.8
4 4 45.0000 90.0000 23.08 -I- 3.0 51.4 86.1 0.891 72.3
5 4 45.0000 180.0000 19.18 --- 3.0 -16.7 18.0 0.010 2.0
1 5 90.0000 -180.0000 18.79 3F2 17.0 19.8 54.9 0.010 38.8
2 5 90.0000 -90.0000 18.79 3F2 17.0 19.8 54.9 0.010 38.8
3 5 90.0000 0.0000 18.79 3F2 17.0 19.8 54.9 0.010 38.8
4 5 90.0000 90.0000 18.79 3F2 17.0 19.8 54.9 0.010 38.8
5 5 90.0000 180.0000 18.79 3F2 17.0 19.8 54.9 0.010 38.8