attributes for comparision

[jaigsingla]

Dear all,

As we can get Text content of shape attribute name and numerical expression in text-> priority.

How to get attribute numeric values for comparison ?\

thanks,
Jay

[smarttigerfly]

I think you should use script like this:

const char* styles_css =
R"(
p{fill:#000080;fill-opacity: 0.5;stroke:#3f763f;stroke-width: 1px;altitude-clamping:terrain;altitude-technique:drape;}
p1:p{fill:#66FF66;}
p2:p{fill:#33CC33;}
p3:p{fill:#009900;}
)";

const char* script_source = R"(
function getStyleClass()
{
    var pop = parseFloat(feature.properties.pop);
    if ( pop<200000 ) {return "p1";}
    else if (pop < 500000) {return "p2";}
    else {return "p3";}
}
)";

int main(int argc, char** argv)
{
    osgEarth::initialize();
    osg::ArgumentParser arguments(&argc, argv);

    // create the map.
    osg::ref_ptr<Map> map = new Map();

    {
        GDALImageLayer* layer = new GDALImageLayer();
        layer->setURL("E:\\osgEarthData\\data\\world.tif");
        map->addLayer(layer);
    }


    // create a feature source to load the building footprint shapefile.
    OGRFeatureSource* data = new OGRFeatureSource();
    data->setName("buildings-data");
    data->setURL("E:\\osgEarthData\\css\\sld_cookbook_polygon.shp");
    Status s = data->open();
    if (s.isError())
    {
        OE_WARN << s.message() << std::endl;
        exit(0);
    }

    StyleSheet* stringSheet = new StyleSheet();
    stringSheet->addStylesFromCSS(styles_css);
    stringSheet->setScript(new StyleSheet::ScriptDef(script_source));
    stringSheet->addSelector(StyleSelector("default", StringExpression("getStyleClass()")));

    FeatureModelLayer* layer = new FeatureModelLayer();
    layer->setFeatureSource(data);
    layer->setStyleSheet(stringSheet);

    map->addLayer(layer);

    if (layer->getStatus().isError())
    {
        OE_WARN << layer->getStatus().message() << std::endl;
    }

    // initialize a viewer:
    osgViewer::Viewer viewer(arguments);

    EarthManipulator* manip = new EarthManipulator();
    viewer.setCameraManipulator(manip);

    osg::Group* root = new osg::Group();
    viewer.setSceneData(root);

    // make the map scene graph:
    MapNode* mapNode = new MapNode(map.get());
    root->addChild(mapNode);

    GLUtils::setGlobalDefaults(root->getOrCreateStateSet());

    viewer.realize();
    // zoom to a good startup position
    manip->setViewpoint(Viewpoint(
        "Home",
        0, 0, 0,   // longitude, latitude, altitude
        180, 0, 34500000.0), // heading, pitch, range
        5.0);                    // duration

    // This will mitigate near clip plane issues if you zoom in close to the ground:
    LogarithmicDepthBuffer buf;
    buf.install(viewer.getCamera());

    return viewer.run();
}

The shapefile sld_cookbook_polygon.shp has the pop attribute.

[jaigsingla]

int main(int argc, char** argv)
{
osg::ArgumentParser arguments(&argc, argv);
osg::DisplaySettings::instance()->setMinimumNumStencilBits(8);
Map* map = new Map();
// Add an imagery layer (blue marble from a TMS source)
{
GDALOptions gdal;
gdal.url() = "G:/data/viz/world.tif";
ImageLayer* baseLayer = new ImageLayer("world", gdal);
map->addImageLayer(baseLayer);
}
osgViewer::Viewer viewer(arguments);

//FeatureSource featureSrc;
OGRFeatureOptions featureOptions;
featureOptions.name() = "Shapefile";
featureOptions.url() = "G:/viz/data/world.shp";

    osg::ref_ptr<FeatureSource> features = FeatureSourceFactory::create(featureOptions);
   osg::ref_ptr<FeatureCursor> cursor = features->createFeatureCursor();

   Style labelStyle;

   TextSymbol* text = labelStyle.getOrCreateSymbol<TextSymbol>();

   std::string g_priorityAttrib;

   g_priorityAttrib = "pop_cntry";

   text->content() = StringExpression("[cntry_name]");

   text->priority() = NumericExpression("[pop_cntry]");

   text->removeDuplicateLabels() = true;

    while (cursor->hasMore())
   {
          text->removeDuplicateLabels() = true;
          Feature* feature = cursor->nextFeature();
          float pop = feature->getDouble(g_priorityAttrib, 0.0);
             if (pop > 10000000) {
                 text->fill()->color() = Color::White;
                 text->halo()->color() = Color::Blue;
                 text->size() = 18.0f;
          }
          else{
          text->size() = 16.0f;
          text->alignment() = TextSymbol::ALIGN_CENTER_CENTER;
          text->fill()->color() = Color::White;
          text->halo()->color() = Color::DarkGray;
          }
   }

   // and configure a model layer:

   FeatureGeomModelOptions geomOptions;

   geomOptions.featureOptions() = featureOptions;

   geomOptions.styles() = new StyleSheet();

   geomOptions.styles()->addStyle(labelStyle);

   ModelLayerOptions layerOptions("my features", geomOptions);

   MapNodeOptions mapNodeOptions;

   mapNodeOptions.enableLighting() = false;

   map->addModelLayer(new ModelLayer(layerOptions));

   MapNode* mapNode = new MapNode(map, mapNodeOptions);

  osgEarth::Util::EarthManipulator* manip = new EarthManipulator();

   root = new osg::Group();
   root->addChild(mapNode);
   viewer.setSceneData(root);
   viewer.setCameraManipulator(manip);
   //Viewer

viewer.addEventHandler(new osgViewer::StatsHandler);
viewer.addEventHandler(new osgViewer::WindowSizeHandler);
viewer.addEventHandler(new osgViewer::ThreadingHandler());
viewer.run();
return 0;

thanks for the reply..

I was trying with above mentioned code. It is giving some access violation reading location error at cursor->hasMore

Are you using osgearth 2.8 or later??

thanks
Jay