Filter features in scene

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// Copyright 2023 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.

import ArcGIS
import SwiftUI

struct FilterFeaturesInSceneView: View {
    /// The result of the loading the view model for this sample.
    @State private var modelResult: Result<Model, any Error>?

    var body: some View {
        switch modelResult {
        case .success(let model):
            SceneView(scene: model.scene, graphicsOverlays: [model.graphicsOverlay])
                .toolbar {
                    ToolbarItem(placement: .bottomBar) {
                        switch model.filterState {
                        case .filter:
                            Button("Filter", action: model.filterScene)
                        case .showDetailedBuildings:
                            Button("Show Detailed Buildings", action: model.showDetailedBuildings)
                        case .reset:
                            Button("Reset", action: model.resetScene)
                        }
                    }
                }
        case .failure(let error):
            ContentUnavailableView {
                Label("Error Setting Up Sample", systemImage: "exclamationmark.triangle")
            } description: {
                Text(error.localizedDescription)
            } actions: {
                Button("Retry") { modelResult = nil }
            }
        case .none:
            ProgressView("Loading model")
                .task {
                    modelResult = await Result(awaiting: Model.init)
                }
        }
    }
}

private extension FilterFeaturesInSceneView {
    /// The model used to store the geo model and other expensive objects
    /// used in this view.
    @Observable
    final class Model {
        /// The scene for this sample.
        let scene: ArcGIS.Scene = {
            let scene = Scene()

            // Adds the World Elevation 3D elevation source to the scene's base surface.
            let elevationSource = ArcGISTiledElevationSource(url: .worldElevationService)
            scene.baseSurface.addElevationSource(elevationSource)

            // Sets the initial viewpoint for the scene.
            scene.initialViewpoint = .sanFranciscoBuildings

            return scene
        }()

        /// The "Buildings" ArcGIS scene layer from the scene's basemap.
        private let buildingsLayer: ArcGISSceneLayer

        /// An ArcGIS scene layer containing detailed buildings in San Francisco, CA, USA.
        private let detailedBuildingsLayer = ArcGISSceneLayer(url: .sanFranciscoBuildings)

        /// The graphics overlay for the scene view.
        let graphicsOverlay = GraphicsOverlay()

        /// A polygon filter for filtering the features in the `buildingsLayer`.
        private let polygonFilter: SceneLayerPolygonFilter

        /// A red extent boundary graphic that represents the full extent of the detailed buildings scene layer.
        private let sanFranciscoExtentGraphic: Graphic = {
            // Creates a graphic from a red outline symbol.
            let redLineSymbol = SimpleLineSymbol(color: .red, width: 5)
            let redOutlineFillSymbol = SimpleFillSymbol(color: .clear, outline: redLineSymbol)
            let graphic = Graphic(symbol: redOutlineFillSymbol)

            // Initially hides the graphic, since the filter has not been applied yet.
            graphic.isVisible = false

            return graphic
        }()

        /// The different states for filtering features in a scene.
        enum FilterState {
            case filter, showDetailedBuildings, reset
        }

        /// The filter state for the scene view.
        private(set) var filterState: FilterState = .filter

        /// An error that can occur during the model's initialization.
        enum InitializationError: Error {
            case missingBuildingsLayer
            case missingDetailedBuildingsLayerExtent
        }

        init() async throws {
            // Creates the "Navigation" 3D basemap and sets it on the scene.
            let basemap = Basemap(url: .navigation3DBasemap)!
            scene.basemap = basemap

            // Gets the "Buildings" base layer from the basemap.
            try await basemap.load()
            guard let buildingsLayer = basemap.baseLayers
                .first(where: { $0.name == "Buildings" }) as? ArcGISSceneLayer else {
                throw InitializationError.missingBuildingsLayer
            }
            self.buildingsLayer = buildingsLayer

            // Creates a polygon from the detailedBuildingsLayer's extent.
            try await detailedBuildingsLayer.load()
            guard let extent = detailedBuildingsLayer.fullExtent else {
                throw InitializationError.missingDetailedBuildingsLayerExtent
            }
            let polygon = Polygon(
                points: [
                    Point(x: extent.xMin, y: extent.yMin),
                    Point(x: extent.xMax, y: extent.yMin),
                    Point(x: extent.xMax, y: extent.yMax),
                    Point(x: extent.xMin, y: extent.yMax)
                ]
            )

            // Adds the polygon to the graphic and adds the graphic to the overlay.
            sanFranciscoExtentGraphic.geometry = polygon
            graphicsOverlay.addGraphic(sanFranciscoExtentGraphic)

            // Creates a disjoint scene layer polygon filter using the polygon.
            polygonFilter = SceneLayerPolygonFilter(
                polygons: [polygon],
                spatialRelationship: .disjoint
            )

            // Adds the detailed buildings layer to the scene.
            // The layer is also initially hidden to that it doesn't
            // clip into the `buildingsLayer` while it is unfiltered.
            detailedBuildingsLayer.isVisible = false
            scene.addOperationalLayer(detailedBuildingsLayer)
        }

        /// Filters the `buildingsLayer` features within the `detailedBuildingsLayer` extent.
        func filterScene() {
            // Applies the polygon filter to the buildings layer.
            buildingsLayer.polygonFilter = polygonFilter
            // Shows graphic to indicate the filtered extent.
            sanFranciscoExtentGraphic.isVisible = true

            filterState = .showDetailedBuildings
        }

        /// Shows the detailed buildings scene layer.
        func showDetailedBuildings() {
            detailedBuildingsLayer.isVisible = true

            filterState = .reset
        }

        /// Resets the scene filters and hides the detailed buildings and extent graphic.
        func resetScene() {
            // Hides the detailed buildings layer.
            detailedBuildingsLayer.isVisible = false
            // Removes the polygon filter from the building layer.
            buildingsLayer.polygonFilter = nil
            // Hides the red extent boundary graphic.
            sanFranciscoExtentGraphic.isVisible = false

            filterState = .filter
        }
    }
}

private extension URL {
    /// The URL to the "Navigation" 3D basemap on ArcGIS Online.
    static var navigation3DBasemap: URL {
        URL(string: "https://www.arcgis.com/home/item.html?id=00a5f468dda941d7bf0b51c144aae3f0")!
    }

    /// The URL to the San Francisco Buildings scene server on ArcGIS REST.
    static var sanFranciscoBuildings: URL {
        URL(string: "https://tiles.arcgis.com/tiles/z2tnIkrLQ2BRzr6P/arcgis/rest/services/SanFrancisco_Bldgs/SceneServer")!
    }

    /// The URL to the World Elevation 3D image server on ArcGIS REST.
    static var worldElevationService: URL {
        URL(string: "https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer")!
    }
}

private extension Viewpoint {
    /// The initial viewpoint to be displayed when the sample is first opened.
    static let sanFranciscoBuildings = Viewpoint(
        latitude: .nan,
        longitude: .nan,
        scale: .nan,
        camera: Camera(
            latitude: 37.702425,
            longitude: -122.421008,
            altitude: 207,
            heading: 60,
            pitch: 70,
            roll: 0
        )
    )
}

#Preview {
    NavigationStack {
        FilterFeaturesInSceneView()
    }
}