Extrude graphics

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Extrude graphics based on an attribute value.

screenshot

Use case

Graphics representing features can be vertically extruded to represent properties of the data that might otherwise go unseen. Extrusion can add visual prominence to data beyond what may be offered by varying the color, size, or shape of symbol alone. For example, graphics representing wind turbines in a wind farm application can be extruded by a real-world "height" attribute so that they can be visualized in a landscape. Likewise, census data can be extruded by a thematic "population" attribute to visually convey population levels across a country.

How to use the sample

Run the sample. Note that the graphics are extruded to the level set in their height property.

How it works

  1. Create a GraphicsOverlay and SimpleRenderer.
  2. Get the renderer's SceneProperties using renderer::sceneProperties().
  3. Set the extrusion mode for the renderer with props::setExtrusionMode(ExtrusionMode::BaseHeight).
  4. Specify the attribute name of the graphic that the extrusion mode will use: props::setExtrusionExpression("[height]").
  5. Set the renderer on the graphics overlay using graphicsOverlay::setRenderer(renderer).
  6. Create graphics with the attribute set: graphic::attributes()::insertAttribute("height", z).

Relevant API

  • RendererSceneProperties
  • ExtrusionMode
  • SceneProperties::setExtrusionExpression()
  • SimpleRenderer

About the data

Data is hard coded in this sample as a demonstration of how to create and set an attribute to a graphic. To extrude graphics based on pre-existing attributes (e.g. from a feature layer) see the FeatureLayerExtrusion sample.

Tags

3D, extrude, extrusion, height, scene, visualization

Sample Code

ExtrudeGraphics.cppExtrudeGraphics.cppExtrudeGraphics.hExtrudeGraphics.qml
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// [WriteFile Name=ExtrudeGraphics, Category=Scenes]
// [Legal]
// Copyright 2016 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 "ExtrudeGraphics.h"

#include "Scene.h"
#include "SceneQuickView.h"
#include "Basemap.h"
#include "ArcGISTiledElevationSource.h"
#include "SimpleRenderer.h"
#include "PointBuilder.h"
#include "Point.h"
#include "PolygonBuilder.h"
#include "Polygon.h"
#include "SimpleFillSymbol.h"

#include <cmath>
#include <ctime>

using namespace Esri::ArcGISRuntime;

ExtrudeGraphics::ExtrudeGraphics(QQuickItem* parent) :
  QQuickItem(parent)
{
  srand(time(nullptr));
}

ExtrudeGraphics::~ExtrudeGraphics() = default;

void ExtrudeGraphics::init()
{
  qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
  qmlRegisterType<ExtrudeGraphics>("Esri.Samples", 1, 0, "ExtrudeGraphicsSample");
}

void ExtrudeGraphics::componentComplete()
{
  QQuickItem::componentComplete();

  // find QML SceneView component
  m_sceneView = findChild<SceneQuickView*>("sceneView");

  // create a new basemap instance
  Basemap* basemap = new Basemap(BasemapStyle::ArcGISImageryStandard, this);
  // create a new scene instance
  m_scene = new Scene(basemap, this);
  // set scene on the scene view
  m_sceneView->setArcGISScene(m_scene);

  // create a new elevation source
  ArcGISTiledElevationSource* elevationSource = new ArcGISTiledElevationSource(m_elevationSourceUrl, this);
  // add the elevation source to the scene to display elevation
  m_scene->baseSurface()->elevationSources()->append(elevationSource);

  // create a camera
  const double latitude = 28.4;
  const double longitude = 83.9;
  const double altitude = 10010.0;
  const double heading = 10.0;
  const double pitch = 80.0;
  const double roll = 0.0;
  Camera camera(latitude, longitude, altitude, heading, pitch, roll);
  // set the viewpoint
  m_sceneView->setViewpointCameraAndWait(camera);

  // graphics location
  double lon = camera.location().x() - 0.03;
  double lat = camera.location().y() + 0.2;

  GraphicsOverlay* graphicsOverlay = new GraphicsOverlay(this);

  // set renderer with extrusion property
  SimpleRenderer* renderer = new SimpleRenderer(this);
  RendererSceneProperties props = renderer->sceneProperties();
  props.setExtrusionMode(ExtrusionMode::BaseHeight);
  props.setExtrusionExpression("[height]");
  renderer->setSceneProperties(props);
  SimpleFillSymbol* sfs = new SimpleFillSymbol(SimpleFillSymbolStyle::Solid, QColor("red"), this);
  renderer->setSymbol(sfs);
  graphicsOverlay->setRenderer(renderer);

  // setup graphic locations
  QList<Point> pointsList;
  for (int i = 0; i <= 100; i++)
  {
    Point point(i / 10 * (m_size * 2) + lon, i % 10 * (m_size * 2) + lat, m_sceneView->spatialReference());
    pointsList.append(point);
  }

  for (const Point& point : pointsList)
  {
    // create a random z value
    const int randNum = rand() % 6 + 1;
    const double z = m_maxZ * randNum;

    // create a list of points
    const QList<Point> points { Point(point.x(), point.y(), z)
                              , Point(point.x() + m_size, point.y(), z)
                              , Point(point.x() + m_size, point.y() + m_size, z)
                              , Point(point.x(), point.y() + m_size, z)
                              };

    // create a new graphic
    Graphic* graphic = new Graphic(createPolygonFromPoints(points), this);
    // add a height attribute to the graphic using the attribute list model
    // the extrusion will be applied to this attribute. See the expression above
    graphic->attributes()->insertAttribute("height", z);
    // add the graphic to the graphic overlay
    graphicsOverlay->graphics()->append(graphic);
  }

  m_sceneView->graphicsOverlays()->append(graphicsOverlay);
}

// helper to create polygon from points
Esri::ArcGISRuntime::Polygon ExtrudeGraphics::createPolygonFromPoints(QList<Point> points)
{
  Esri::ArcGISRuntime::Polygon polygon;
  if (points.length() == 0)
    return polygon;

  // create a polygon builder
  PolygonBuilder* pb = new PolygonBuilder(m_sceneView->spatialReference(), this);
  for (const Point& point : points)
  {
    // add each point to the builder object
    pb->addPoint(point);
  }
  return polygon = pb->toGeometry();
}

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