LineOfSightViewModel

// instantiate a new view model
const losViewModel = new LineOfSightViewModel({
 view: view
});

// set an observer
losViewModel.observer = new Point({
  latitude: 42.3521,
  longitude: -71.0559,
  z: 147.139
});

// set a target by passing in a LineOfSightTarget to the targets collection
losViewModel.targets = [new LineOfSightTarget({
   location: new Point({
     latitude: 42.352,
     longitude: -71.051,
     z: 0
   })
})];

// when using JavaScript LineOfSightTarget can be autocast
losViewModel.targets = [{
   location: {
     latitude: 42.352,
     longitude: -71.051,
     z: 0
   }
}];

viewModel.start();

reactiveUtils.watch(
  () => losViewModel.observer,
  (value) => {
    // do something with the value
  }
);

const highlightHandles = [];

reactiveUtils.watch(
  () => {
    // Watch the whole expression. The callback will be called if any target is added or removed
    // and also if any of the target's `intersectedGraphic` property changes.
    viewModel.targets
      .map((target) => target.intersectedGraphic)
      .map((graphic) => !!graphic)
      .toArray()
  },
  (intersectedGraphics) => {
    // Remove the previous highlights
    highlightHandles.forEach((handle) => handle.remove());

    // Highlight all the intersected graphics
    highlightHandles = intersectedGraphics.map((graphic) => {
      return layerView.highlight(graphic);
    });
  }
);

Property Overview

Property Details

analysis LineOfSightAnalysisautocastreadonly

Since: ArcGIS Maps SDK for JavaScript 4.23

The line of sight analysis object being created or modified by the view model.

This property can be set during view model construction, to provide an existing analysis to the view model for modification. Properties on the analysis can also be updated once it's assigned to the view model.

If no analysis is provided during view model construction, the view model automatically creates its own analysis and adds it to the view. In this case, the analysis will also be automatically removed from the view when the view model is destroyed.

Example

// Construct a line of sight analysis object outside of the view model
const analysis = new LineOfSightAnalysis({
  observer: {
    type: "point", // autocasts as new Point()
    x: 7.67,
    y: 45.981,
    z: 3435.765
  },
  targets: [{
    location: {
      type: "point",
      x: 7.659,
      y: 45.976,
      z: 4437
    }
  }]
});

// Ensure that the analysis is added to the view
view.analyses.add(analysis);

// Frame the analysis in the view
view.goTo(analysis.extent);

// Pass the analysis object as a constructor parameter to modify it using the view model
const viewModel = new LineOfSightViewModel({
  analysis: analysis,
  view: view
});

declaredClass Stringreadonly inherited

The name of the class. The declared class name is formatted as esri.folder.className.

observer Point

The observer's viewpoint from which lines of sight will be drawn towards the targets. The Z value of the point is an absolute value.

state Stringreadonly

The view model's state.

Value	Description
disabled	not ready yet
ready	ready for analysis
creating	observer/target points are being placed
created	finished analysis

Possible Values:"disabled"|"ready"|"creating"|"created"

Default Value:disabled

targets Collection<LineOfSightTarget>

A collection of LineOfSightTarget containing the target location and the analysis results.

view SceneView

The view from which the widget will operate.

Method Overview

Method Details

addHandles(handleOrHandles, groupKey)inherited

Since: ArcGIS Maps SDK for JavaScript 4.25

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();

Parameters

handleOrHandles WatchHandle|WatchHandle[] Handles marked for removal once the object is destroyed.

groupKey * optional Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

clear()

Clears the current analysis results. After calling this method, the user can set a new observer and targets.

continue()

If stopped, this method continues the line of sight analysis and the user can add more targets.

hasHandles(groupKey){Boolean}inherited

Since: ArcGIS Maps SDK for JavaScript 4.25

Returns true if a named group of handles exist.

Parameter

groupKey * optional A group key.

Returns

Type	Description
Boolean	Returns true if a named group of handles exist.

Example

// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

removeHandles(groupKey)inherited

Since: ArcGIS Maps SDK for JavaScript 4.25

Removes a group of handles owned by the object.

Parameter

groupKey * optional A group key or an array or collection of group keys to remove.

Example

obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");

start()

Starts a new line of sight analysis.

stop()

Stops the current line of sight analysis, keeping the results in the view. Users can still interact with existing targets and the observer but they can't place new target points.