Display 3D labels in scene

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This sample demonstrates how to display custom labels in a 3D scene.

screenshot

Use case

Labeling features is useful to visually display information or attributes on a scene. For example, city officials or maintenance crews may want to show installation dates of features of a gas network.

How to use the sample

Pan and zoom to explore the scene. Notice the labels showing installation dates of features in the 3D gas network.

How it works

  1. Create a Scene from a PortalItem.
  2. Add the scene to a SceneView and load it.
  3. After loading is complete, obtain the FeatureLayer from one of the GroupLayers in the scene's operationalLayers.
  4. Create a TextSymbol to define how labels are stylized.
  5. After the Scene has loaded, obtain the FeatureLayer from the scene's operationalLayers.
  6. Create an LabelDefinition using an ArcadeLabelExpression.
    • Set the "labelExpressionInfo.expression" key to define what text the label should display. You can use fields of the feature by using $feature.NAME in the expression.
  7. Add the definition to the feature layer's labelDefinitions array.

Relevant API

  • ArcadeLabelExpression
  • FeatureLayer
  • LabelDefinition
  • Scene
  • SceneView
  • TextSymbol

About the data

This sample shows a New York City infrastructure scene hosted on ArcGIS Online.

Tags

3D, arcade, attribute, buildings, label, model, scene, symbol, text, URL, visualization

Sample Code

Display3DLabelsInScene.cppDisplay3DLabelsInScene.cppDisplay3DLabelsInScene.hDisplay3DLabelsInScene.qml
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// [WriteFile Name=Display3DLabelsInScene, Category=Scenes]
// [Legal]
// Copyright 2021 Esri.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "Display3DLabelsInScene.h"

#include "ArcadeLabelExpression.h"
#include "ArcGISTiledElevationSource.h"
#include "FeatureLayer.h"
#include "GroupLayer.h"
#include "LabelDefinition.h"
#include "Layer.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include "TextSymbol.h"

using namespace Esri::ArcGISRuntime;

Display3DLabelsInScene::Display3DLabelsInScene(QObject* parent /* = nullptr */):
  QObject(parent),
  m_scene(new Scene(QUrl("https://www.arcgis.com/home/item.html?id=850dfee7d30f4d9da0ebca34a533c169"), this))
{
  connect(m_scene, &Scene::doneLoading, this, [this]()
  {
    for (Layer* layer : *m_scene->operationalLayers())
    {
      if (layer->name() == "Gas")
      {
        // The gas layer is a GroupLayer type consisting of Layer types.
        // Labels can only be displayed on FeatureLayer types, so we must first convert it to a FeatureLayer class.
        GroupLayer* gasGroupLayer = dynamic_cast<GroupLayer*>(layer);
        if (!gasGroupLayer)
          continue;

        FeatureLayer* gasFeatureLayer = dynamic_cast<FeatureLayer*>(gasGroupLayer->layers()->first());
        if (gasFeatureLayer)
          display3DLabelsOnFeatureLayer(gasFeatureLayer);

        break;
      }
    }
  });
}

void Display3DLabelsInScene::display3DLabelsOnFeatureLayer(FeatureLayer* featureLayer)
{
  TextSymbol* textSymbol = new TextSymbol(this);
  textSymbol->setColor(QColor("#ffa500"));
  textSymbol->setHaloColor(QColor(Qt::white));
  textSymbol->setHaloWidth(2.0);
  textSymbol->setSize(14.0);

  ArcadeLabelExpression* labelExpression = new ArcadeLabelExpression("Text($feature.INSTALLATIONDATE, 'D MMM Y')", this);
  LabelDefinition* labelDefinition = new LabelDefinition(labelExpression, textSymbol, this);
  labelDefinition->setPlacement(LabelingPlacement::LineAboveAlong);
  labelDefinition->setUseCodedValues(true);

  featureLayer->labelDefinitions()->clear();
  featureLayer->labelDefinitions()->append(labelDefinition);
  featureLayer->setLabelsEnabled(true);
}

Display3DLabelsInScene::~Display3DLabelsInScene() = default;

void Display3DLabelsInScene::init()
{
  // Register classes for QML
  qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
  qmlRegisterType<Display3DLabelsInScene>("Esri.Samples", 1, 0, "Display3DLabelsInSceneSample");
}

SceneQuickView* Display3DLabelsInScene::sceneView() const
{
  return m_sceneView;
}

// Set the view (created in QML)
void Display3DLabelsInScene::setSceneView(SceneQuickView* sceneView)
{
  if (!sceneView || sceneView == m_sceneView)
    return;

  m_sceneView = sceneView;
  m_sceneView->setArcGISScene(m_scene);

  emit sceneViewChanged();
}

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