Viewshed (location)

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// Copyright 2018 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 Android.App;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using Esri.ArcGISRuntime.UI.GeoAnalysis;
using System;
using Surface = Esri.ArcGISRuntime.Mapping.Surface;

namespace ArcGISRuntime.Samples.ViewshedLocation
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.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 class ViewshedLocation : Activity
    {
        // Hold a reference to the scene view.
        private SceneView _mySceneView;

        // 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;

        // References to UI elements.
        private SeekBar _headingSlider;

        private SeekBar _pitchSlider;
        private SeekBar _horizontalAngleSlider;
        private SeekBar _verticalAngleSlider;
        private SeekBar _minimumDistanceSlider;
        private SeekBar _maximumDistanceSlider;
        private Switch _analysisVisibilitySwitch;
        private Switch _frustumVisibilitySwitch;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Viewshed (Location)";

            // Create the layout
            CreateLayout();

            // 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.Progress,
                _pitchSlider.Progress,
                _horizontalAngleSlider.Progress,
                _verticalAngleSlider.Progress,
                _minimumDistanceSlider.Progress,
                _maximumDistanceSlider.Progress);

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

            // 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);

            // Create a symbol for the viewpoint.
            _viewpointSymbol = SimpleMarkerSceneSymbol.CreateSphere(System.Drawing.Color.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));

            // 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 = System.Drawing.Color.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)
        {
            // Reset the horizontal and vertical angle if they go out of bounds
            if (_horizontalAngleSlider.Progress < 1) { _horizontalAngleSlider.Progress = 1; }
            if (_verticalAngleSlider.Progress < 1) { _verticalAngleSlider.Progress = 1; }

            // Update the viewshed settings.
            _viewshed.Heading = _headingSlider.Progress;
            _viewshed.Pitch = _pitchSlider.Progress;
            _viewshed.HorizontalAngle = _horizontalAngleSlider.Progress;
            _viewshed.VerticalAngle = _verticalAngleSlider.Progress;
            _viewshed.MinDistance = _minimumDistanceSlider.Progress + 5;
            _viewshed.MaxDistance = _maximumDistanceSlider.Progress;

            // Update visibility of the viewshed analysis.
            _viewshed.IsVisible = _analysisVisibilitySwitch.Checked;

            // 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 = _frustumVisibilitySwitch.Checked;
        }

        private void CreateLayout()
        {
            // Create a new vertical layout for the app
            LinearLayout layout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Heading
            TextView headingLabel = new TextView(this) { Text = "Heading:" };
            _headingSlider = new SeekBar(this) { Max = 360 };
            layout.AddView(headingLabel);
            layout.AddView(_headingSlider);

            // Pitch
            TextView pitchLabel = new TextView(this) { Text = "Pitch:" };
            _pitchSlider = new SeekBar(this) { Max = 180, Progress = 60 };
            layout.AddView(pitchLabel);
            layout.AddView(_pitchSlider);

            // Horizontal Angle
            TextView horizontalAngleLabel = new TextView(this) { Text = "Horizontal Angle:" };
            _horizontalAngleSlider = new SeekBar(this) { Max = 120, Progress = 75 };
            layout.AddView(horizontalAngleLabel);
            layout.AddView(_horizontalAngleSlider);

            // Vertical Angle
            TextView verticalAngleLabel = new TextView(this) { Text = "Vertical Angle:" };
            _verticalAngleSlider = new SeekBar(this) { Max = 120, Progress = 90 };
            layout.AddView(verticalAngleLabel);
            layout.AddView(_verticalAngleSlider);

            // Minimum Distance
            TextView minimumDistanceLabel = new TextView(this) { Text = "Minimum Distance:" };
            _minimumDistanceSlider = new SeekBar(this) { Max = 8994 };
            layout.AddView(minimumDistanceLabel);
            layout.AddView(_minimumDistanceSlider);
            layout.SetHorizontalGravity(GravityFlags.FillHorizontal);

            // Maximum Distance
            TextView maximumDistanceLabel = new TextView(this) { Text = "Maximum Distance:" };
            _maximumDistanceSlider = new SeekBar(this) { Max = 9999, Progress = 1500 };
            layout.AddView(maximumDistanceLabel);
            layout.AddView(_maximumDistanceSlider);

            // Analysis Visibility
            TextView analysisVisibilityLabel = new TextView(this) { Text = "Analysis Visibility:" };
            _analysisVisibilitySwitch = new Switch(this) { Checked = true };
            layout.AddView(analysisVisibilityLabel);
            layout.AddView(_analysisVisibilitySwitch);

            // Frustum Visibility
            TextView frustumVisibilityLabel = new TextView(this) { Text = "Frustum Visibility:" };
            _frustumVisibilitySwitch = new Switch(this) { Checked = false };
            layout.AddView(frustumVisibilityLabel);
            layout.AddView(_frustumVisibilitySwitch);

            // Add the scene view to the layout
            _mySceneView = new SceneView(this);
            layout.AddView(_mySceneView);

            // Show the layout in the app
            SetContentView(layout);

            // Subscribe to events
            _headingSlider.ProgressChanged += HandleSettingsChange;
            _pitchSlider.ProgressChanged += HandleSettingsChange;
            _horizontalAngleSlider.ProgressChanged += HandleSettingsChange;
            _verticalAngleSlider.ProgressChanged += HandleSettingsChange;
            _minimumDistanceSlider.ProgressChanged += HandleSettingsChange;
            _maximumDistanceSlider.ProgressChanged += HandleSettingsChange;
            _analysisVisibilitySwitch.Click += HandleSettingsChange;
            _frustumVisibilitySwitch.Click += HandleSettingsChange;
        }

        protected override void OnDestroy()
        {
            base.OnDestroy();

            // Remove the sceneview
            (_mySceneView.Parent as ViewGroup).RemoveView(_mySceneView);
            _mySceneView.Dispose();
            _mySceneView = null;
        }
    }
}