This sample demonstrates how to display custom labels in a 3D scene.
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
- Create a
Scene
from aPortalItem
. - Add the scene to a
SceneView
and load it. - After loading is complete, obtain the
FeatureLayer
from one of theGroupLayer
s in the scene'soperationalLayers
. - Create a
TextSymbol
to define how labels are stylized. - After the
Scene
has loaded, obtain theFeatureLayer
from the scene'soperationalLayers
. - Create an
LabelDefinition
using anArcadeLabelExpression
.- 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.
- Set the "labelExpressionInfo.expression" key to define what text the label should display. You can use fields of the feature by using
- 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
// [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 "FeatureLayer.h"
#include "LabelDefinition.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include "TextSymbol.h"
#include "Error.h"
#include "LayerListModel.h"
#include "GroupLayer.h"
#include "ServiceTypes.h"
#include "LabelDefinitionListModel.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();
}