Show viewshed from geoelement in scene

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
// Copyright 2025 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 'dart:async';
import 'dart:io';

import 'package:arcgis_maps/arcgis_maps.dart';
import 'package:arcgis_maps_sdk_flutter_samples/common/common.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';

class ShowViewshedFromGeoelementInScene extends StatefulWidget {
  const ShowViewshedFromGeoelementInScene({super.key});

  @override
  State<ShowViewshedFromGeoelementInScene> createState() =>
      _ShowViewshedFromGeoelementInSceneState();
}

class _ShowViewshedFromGeoelementInSceneState
    extends State<ShowViewshedFromGeoelementInScene>
    with SampleStateSupport {
  // Create a controller for the scene view.
  final _sceneViewController = ArcGISSceneView.createController();

  // The graphic for the tank.
  Graphic? _tankGraphic;

  // Timer for animation.
  Timer? _animationTimer;

  // Waypoint for tank graphic.
  ArcGISPoint? _waypoint;

  // A flag for when the map view is ready and controls can be used.
  var _ready = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        top: false,
        left: false,
        right: false,
        child: Stack(
          children: [
            // Add a scene view to the widget tree and set a controller.
            ArcGISSceneView(
              controllerProvider: () => _sceneViewController,
              onSceneViewReady: onSceneViewReady,
              onTap: onTap,
            ),
            // Display a progress indicator and prevent interaction until state is ready.
            LoadingIndicator(visible: !_ready),
            // Banner at the top.
            SafeArea(
              child: IgnorePointer(
                child: Container(
                  width: double.infinity,
                  padding: const EdgeInsets.all(10),
                  color: Colors.black.withValues(alpha: 0.5),
                  child: const Text(
                    'Tap on the map to move the tank and update the viewshed.',
                    textAlign: TextAlign.center,
                    style: TextStyle(color: Colors.white, fontSize: 16),
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  // Called when the scene view is ready.
  Future<void> onSceneViewReady() async {
    // Create and configure the scene with elevation.
    final scene = _createScene();
    // Assign the scene to the scene view controller.
    _sceneViewController.arcGISScene = scene;

    // Load the tank graphic from the local data.
    _tankGraphic = await _loadTankGraphic();

    // Add the tank graphic to the scene.
    _addTankToScene(_tankGraphic!);

    // Set up the orbit camera controller to follow the tank.
    _setupCameraController(_tankGraphic!);

    // Add the viewshed to the scene.
    _addViewshedToScene(_tankGraphic!);

    setState(() => _ready = true);
  }

  // Creates a scene with an imagery basemap and adds elevation data.
  ArcGISScene _createScene() {
    final scene = ArcGISScene.withBasemapStyle(BasemapStyle.arcGISImagery);

    // Add world elevation source to the scene's surface.
    final elevationSource = ArcGISTiledElevationSource.withUri(
      Uri.parse(
        'https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer',
      ),
    );
    scene.baseSurface.elevationSources.add(elevationSource);

    // Create the building layer and add it to the scene.
    final buildingsLayer = ArcGISSceneLayer.withUri(
      Uri.parse(
        'https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0',
      ),
    );
    scene.operationalLayers.add(buildingsLayer);

    return scene;
  }

  // Convert the tapped location into a waypoint within the scene and initiate the tank's animation towards the waypoint.
  Future<void> onTap(Offset localPosition) async {
    // Convert localPosition to scenePoint.
    final scenePoint = await _sceneViewController.screenToLocation(
      screen: localPosition,
    );

    setState(() => _waypoint = scenePoint);

    _startTankAnimation();
  }

  // Animate the tank toward the waypoint.
  void _startTankAnimation() {
    // Cancel any existing timer.
    _animationTimer?.cancel();
    _animationTimer = Timer.periodic(const Duration(milliseconds: 100), (
      timer,
    ) async {
      if (_tankGraphic == null || _waypoint == null) return;

      final tempPos = _tankGraphic!.geometry! as ArcGISPoint;

      final currentPos = ArcGISPoint(
        x: tempPos.x,
        y: tempPos.y,
        spatialReference: SpatialReference.wgs84,
      );
      final target = ArcGISPoint(
        x: _waypoint!.x,
        y: _waypoint!.y,
        spatialReference: SpatialReference.wgs84,
      );

      // Use geodetic distance to get distance and azimuth.
      final result = GeometryEngine.distanceGeodetic(
        point1: currentPos,
        point2: target,
        distanceUnit: LinearUnit(unitId: LinearUnitId.meters),
        azimuthUnit: AngularUnit(unitId: AngularUnitId.degrees),
        curveType: GeodeticCurveType.geodesic,
      );

      final distance = result.distance;
      final azimuth = result.azimuth1;

      // Stop if close enough.
      if (distance <= 5) {
        _waypoint = null;
        timer.cancel();
        return;
      }

      // Move a small step toward the waypoint.
      const step = 1.0; // meters
      final movedPoints = GeometryEngine.moveGeodetic(
        pointCollection: [currentPos],
        distance: step,
        azimuth: azimuth,
        distanceUnit: LinearUnit(unitId: LinearUnitId.meters),
        azimuthUnit: AngularUnit(unitId: AngularUnitId.degrees),
        curveType: GeodeticCurveType.geodesic,
      );

      if (movedPoints.isEmpty) return;

      final newPoint = movedPoints.first;
      _tankGraphic!.geometry = newPoint;

      // Update heading.
      final currentHeading =
          (_tankGraphic!.attributes['HEADING'] as num?)?.toDouble() ?? 0.0;

      final headingDiff = shortestAngle(currentHeading, azimuth);
      final newHeading = currentHeading + headingDiff / 10;

      _tankGraphic!.attributes['HEADING'] = newHeading;
    });
  }

  // Calculate shortest angle to rotate.
  double shortestAngle(double from, double to) {
    final difference = (to - from + 540) % 360 - 180;
    return difference;
  }

  // Loads the 3D tank model from local sample data and returns it as a Graphic.
  Future<Graphic> _loadTankGraphic() async {
    const downloadFileName = 'bradley_low_3ds';

    final appDir = await getApplicationDocumentsDirectory();
    final zipFile = File('${appDir.absolute.path}/$downloadFileName.zip');
    if (!zipFile.existsSync()) {
      await downloadSampleDataWithProgress(
        itemIds: ['07d62a792ab6496d9b772a24efea45d0'],
        destinationFiles: [zipFile],
      );
    }

    final tankModelPath =
        '${appDir.absolute.path}/$downloadFileName/bradle.3ds';

    // Define the tank symbol.
    final tankSymbol =
        ModelSceneSymbol.withUri(uri: Uri.parse(tankModelPath), scale: 10)
          ..heading = 90
          ..anchorPosition = SceneSymbolAnchorPosition.bottom;

    // Return the graphic that combines geometry and symbol.
    return Graphic(
      geometry: ArcGISPoint(x: -4.506390, y: 48.385624),
      attributes: {'HEADING': 0.0},
      symbol: tankSymbol,
    );
  }

  // Adds the tank graphic to a graphics overlay and sets the initial viewpoint.
  void _addTankToScene(Graphic tankGraphic) {
    final graphicsOverlay = GraphicsOverlay()
      ..graphics.add(tankGraphic)
      ..sceneProperties = LayerSceneProperties(
        surfacePlacement: SurfacePlacement.relative,
      );

    // Configure the heading expression for the tank; this will allow the
    // viewshed to update automatically based on the tank's position.
    final renderer = SimpleRenderer()
      ..sceneProperties.headingExpression = '[HEADING]'
      ..sceneProperties.pitchExpression = '[PITCH]'
      ..sceneProperties.rollExpression = '[ROLL]';
    graphicsOverlay.renderer = renderer;

    _sceneViewController.graphicsOverlays.add(graphicsOverlay);
  }

  // Add viewshed to the scene.
  void _addViewshedToScene(Graphic tankGraphic) {
    // Create a GeoElementViewshed attached to the scene.
    final geoElementViewshed =
        GeoElementViewshed(
            geoElement: tankGraphic,
            horizontalAngle: 90,
            verticalAngle: 40,
            headingOffset: 0,
            pitchOffset: 0,
            minDistance: 0.1,
            maxDistance: 250,
          )
          // Offset the observer location to the front of the tank.
          ..offsetZ = 0.5
          ..offsetY = 4;

    // Create an Analysis Overlay and add the viewshed to it.
    final analysisOverlay = AnalysisOverlay()..analyses.add(geoElementViewshed);

    // Add the analysis overlay to the scene view.
    _sceneViewController.analysisOverlays.add(analysisOverlay);
  }

  // Configures the orbit camera controller for the tank graphic.
  void _setupCameraController(Graphic tankGraphic) {
    final cameraController = OrbitGeoElementCameraController(
      targetGeoElement: tankGraphic,
      distance: 200,
    );
    _sceneViewController.cameraController = cameraController;
  }
}