Viewshed (location)

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// Copyright 2022 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: https://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.

using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.GeoAnalysis;

using Colors = System.Drawing.Color;
using GeoViewInputEventArgs = Esri.ArcGISRuntime.Maui.GeoViewInputEventArgs;

namespace ArcGIS.Samples.ViewshedLocation
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Viewshed (location)",
        category: "Analysis",
        description: "Perform a viewshed analysis from a defined vantage point.",
        instructions: "Use the sliders to change the properties (heading, pitch, etc.), of the viewshed and see them updated in real time.",
        tags: new[] { "3D", "frustum", "scene", "viewshed", "visibility analysis" })]
    public partial class ViewshedLocation : ContentPage
    {
        // Hold the URL to the elevation source.
        private readonly Uri _localElevationImageService = new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer");

        // Hold the URL to the buildings scene layer.
        private readonly Uri _buildingsUrl = new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0");

        // Hold a reference to the viewshed analysis.
        private LocationViewshed _viewshed;

        // Hold a reference to the analysis overlay that will hold the viewshed analysis.
        private AnalysisOverlay _analysisOverlay;

        // Graphics overlay for viewpoint symbol.
        private GraphicsOverlay _viewpointOverlay;

        // Symbol for viewpoint.
        private SimpleMarkerSceneSymbol _viewpointSymbol;

        public ViewshedLocation()
        {
            InitializeComponent();

            // Initialize the sample
            Initialize();
        }

        private void Initialize()
        {
            // Create the scene with the imagery basemap.
            Scene myScene = new Scene(BasemapStyle.ArcGISImageryStandard);
            MySceneView.Scene = myScene;

            // Add the surface elevation.
            Surface mySurface = new Surface();
            mySurface.ElevationSources.Add(new ArcGISTiledElevationSource(_localElevationImageService));
            myScene.BaseSurface = mySurface;

            // Add the scene layer.
            ArcGISSceneLayer sceneLayer = new ArcGISSceneLayer(_buildingsUrl);
            myScene.OperationalLayers.Add(sceneLayer);

            // Create the MapPoint representing the initial location.
            MapPoint initialLocation = new MapPoint(-4.5, 48.4, 56.0);

            // Create the location viewshed analysis.
            _viewshed = new LocationViewshed(
                initialLocation,
                HeadingSlider.Value,
                PitchSlider.Value,
                HorizontalAngleSlider.Value,
                VerticalAngleSlider.Value,
                MinimumDistanceSlider.Value,
                MaximumDistanceSlider.Value);

            // Create a camera based on the initial location.
            Camera camera = new Camera(initialLocation, 200.0, 20.0, 70.0, 0.0);

            // Create a symbol for the viewpoint.
            _viewpointSymbol = SimpleMarkerSceneSymbol.CreateSphere(Colors.Blue, 10, SceneSymbolAnchorPosition.Center);

            // Add the symbol to the viewpoint overlay.
            _viewpointOverlay = new GraphicsOverlay
            {
                SceneProperties = new LayerSceneProperties(SurfacePlacement.Absolute)
            };
            _viewpointOverlay.Graphics.Add(new Graphic(initialLocation, _viewpointSymbol));

            // Apply the camera to the scene view.
            MySceneView.SetViewpointCamera(camera);

            // Create an analysis overlay for showing the viewshed analysis.
            _analysisOverlay = new AnalysisOverlay();

            // Add the viewshed analysis to the overlay.
            _analysisOverlay.Analyses.Add(_viewshed);

            // Add the analysis overlay to the SceneView.
            MySceneView.AnalysisOverlays.Add(_analysisOverlay);

            // Add the graphics overlay
            MySceneView.GraphicsOverlays.Add(_viewpointOverlay);

            // Update the frustum outline color.
            // The frustum outline shows the volume in which the viewshed analysis is performed.
            Viewshed.FrustumOutlineColor = Colors.Blue;

            // Subscribe to tap events to enable moving the observer.
            MySceneView.GeoViewTapped += MySceneViewOnGeoViewTapped;
        }

        private void MySceneViewOnGeoViewTapped(object sender, GeoViewInputEventArgs viewInputEventArgs)
        {
            if (viewInputEventArgs.Location == null)
            {
                // User clicked on the sky - don't update the location with invalid value.
                return;
            }

            // Update the viewshed location.
            _viewshed.Location = viewInputEventArgs.Location;

            // Move the location off of the ground.
            _viewshed.Location = new MapPoint(_viewshed.Location.X, _viewshed.Location.Y, _viewshed.Location.Z + 10.0);

            // Update the viewpoint symbol.
            _viewpointOverlay.Graphics.Clear();
            _viewpointOverlay.Graphics.Add(new Graphic(_viewshed.Location, _viewpointSymbol));
        }

        private void HandleSettingsChange(object sender, EventArgs e)
        {
            // Return if viewshed hasn't been created yet. This happens when the sample is starting.
            if (_viewshed == null)
            {
                return;
            }

            // Update the viewshed settings.
            _viewshed.Heading = HeadingSlider.Value;
            _viewshed.Pitch = PitchSlider.Value;
            _viewshed.HorizontalAngle = HorizontalAngleSlider.Value;
            _viewshed.VerticalAngle = VerticalAngleSlider.Value;
            _viewshed.MinDistance = MinimumDistanceSlider.Value;
            _viewshed.MaxDistance = MaximumDistanceSlider.Value;

            // Update visibility of the viewshed analysis.
            _viewshed.IsVisible = AnalysisVisibilityCheck.IsToggled;

            // Update visibility of the frustum. Note that the frustum will be invisible
            //     regardless of this setting if the viewshed analysis is not visible.
            _viewshed.IsFrustumOutlineVisible = FrustumVisibilityCheck.IsToggled;
        }
    }
}