osgEarth 的热力图代码

以下是一个osgEarth生成热力图的示例代码：

#include <osgEarth/MapNode>
#include <osgEarth/GeoData>
#include <osgEarth/Features>
#include <osgEarthSymbology/Style>
#include <osgEarthUtil/Heatmap>

using namespace osgEarth;
using namespace osgEarth::Features;
using namespace osgEarth::Symbology;
using namespace osgEarth::Util;

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

    // 创建地图并加载地形
    Map* map = new Map();
    map->setGlobalOptions(new MapOptions());
    map->getGlobalOptions()->setTerrainOptions(TerrainOptions());
    map->getGlobalOptions()->getTerrainOptions().setDriver("gdal");
    map->getGlobalOptions()->getTerrainOptions().layers().push_back(osgEarth::LayerOptions("world", "http://mapserver.osgeo.org/cgi-bin/wms?", "world"));

    MapNodeOptions mapNodeOptions;
    mapNodeOptions.enableLighting() = false;
    MapNode* mapNode = new MapNode(map, mapNodeOptions);

    // 创建热力图渲染器
    HeatmapOptions heatmapOptions;
    heatmapOptions.radius() = 50.0;
    heatmapOptions.gradient() = Heatmap::GradientType::GT_HEATMAP;

    Heatmap* heatmap = new Heatmap(mapNode, heatmapOptions);

    // 生成热力图数据
    FeatureList features;

    for (int i = 0; i < 1000; i++)
    {
        double lat = 30.0 + (rand() / (RAND_MAX / 20.0) - 10.0);
        double lon = 120.0 + (rand() / (RAND_MAX / 20.0) - 10.0);

        Feature* feature = new Feature(new Point(lon, lat, 0.0, mapNode->getMapSRS()), mapNode->getMapSRS());
        feature->set("value", (double)rand() / RAND_MAX * 100.0);

        features.push_back(feature);
    }

    // 设置热力图样式
    Style style;
    style.getOrCreate<LineSymbol>()->stroke()->color() = Color::White;
    style.getOrCreate<PointSymbol>()->size() = 20.0f;
    style.getOrCreate<PointSymbol>()->fill()->color() = Color::Red;
    style.getOrCreate<PointSymbol>()->stroke()->color() = Color::White;
    style.getOrCreate<TextSymbol>()->halo()->color() = Color::Black;
    style.getOrCreate<TextSymbol>()->alignment() = TextSymbol::ALIGN_CENTER_BOTTOM;
    style.getOrCreate<TextSymbol>()->content() = "${value}";

    // 开始渲染热力图
    heatmap->setFeatures(features);
    heatmap->setStyle(style);

    // 将热力图添加到场景中并运行
    osg::ref_ptr<osg::Group> root = new osg::Group();
    root->addChild(mapNode);
    root->addChild(heatmap->getNode());

    osgViewer::Viewer viewer(arguments);
    viewer.setSceneData(root);
    return viewer.run();
}

这个示例代码使用osgEarth创建一个地图，并在地图上生成一个包含1000个随机点的热力图。可以使用`HeatmapOptions`类来控制热力图的半径、渐变类型等。热力图的外观可以通过设置`Style`类来调整。最后，将热力图添加到场景中并运行。