Scene

new Cesium.Scene(options)

The container for all 3D graphical objects and state in a Cesium virtual scene. Generally, a scene is not created directly; instead, it is implicitly created by CesiumWidget.
Name Type Description
options object Object with the following properties:
Name Type Default Description
canvas HTMLCanvasElement The HTML canvas element to create the scene for.
contextOptions ContextOptions optional Context and WebGL creation properties.
creditContainer Element optional The HTML element in which the credits will be displayed.
creditViewport Element optional The HTML element in which to display the credit popup. If not specified, the viewport will be a added as a sibling of the canvas.
mapProjection MapProjection new GeographicProjection() optional The map projection to use in 2D and Columbus View modes.
orderIndependentTranslucency boolean true optional If true and the configuration supports it, use order independent translucency.
scene3DOnly boolean false optional If true, optimizes memory use and performance for 3D mode but disables the ability to use 2D or Columbus View.
shadows boolean false optional Determines if shadows are cast by light sources.
mapMode2D MapMode2D MapMode2D.INFINITE_SCROLL optional Determines if the 2D map is rotatable or can be scrolled infinitely in the horizontal direction.
requestRenderMode boolean false optional If true, rendering a frame will only occur when needed as determined by changes within the scene. Enabling improves performance of the application, but requires using Scene#requestRender to render a new frame explicitly in this mode. This will be necessary in many cases after making changes to the scene in other parts of the API. See Improving Performance with Explicit Rendering.
maximumRenderTimeChange number 0.0 optional If requestRenderMode is true, this value defines the maximum change in simulation time allowed before a render is requested. See Improving Performance with Explicit Rendering.
depthPlaneEllipsoidOffset number 0.0 optional Adjust the DepthPlane to address rendering artefacts below ellipsoid zero elevation.
msaaSamples number 1 optional If provided, this value controls the rate of multisample antialiasing. Typical multisampling rates are 2, 4, and sometimes 8 samples per pixel. Higher sampling rates of MSAA may impact performance in exchange for improved visual quality. This value only applies to WebGL2 contexts that support multisample render targets.
Throws:
Example:
// Create scene without anisotropic texture filtering
const scene = new Cesium.Scene({
  canvas : canvas,
  contextOptions : {
    allowTextureFilterAnisotropic : false
  }
});
See:

Members

additionalLights : Array.<PunctualLight>

场景内额外的灯光。
Example:
scene.additionalLights.add(new Cesium.PunctualLight({
  type: Cesium.LightType.POINT,
  position: pointLightPosition,  // 世界坐标
  range: 100,
  color: Cesium.Color.WHITE,
}));

scene.additionalLights.add(new Cesium.PunctualLight({
  type: Cesium.LightType.SPOT,
  position: spotLightPosition,   // 世界坐标
  direction: spotLightDirection, // 世界坐标
  intensity: 100,
  color: Cesium.Color.WHITE,
});

scene.additionalLights.add(new Cesium.PunctualLight({
  type: Cesium.LightType.DIRECTIONAL,
  direction: directionalLightDirection,  // 世界坐标
  intensity: 1,
  color: Cesium.Color.WHITE,
});
The background color, which is only visible if there is no sky box, i.e., Scene#skyBox is undefined.
Default Value: Color.BLACK
See:
Gets or sets the camera.

readonly cameraUnderground : boolean

Whether or not the camera is underneath the globe.
Default Value: false

readonly canvas : HTMLCanvasElement

Gets the canvas element to which this scene is bound.

readonly clampToHeightSupported : boolean

Returns true if the Scene#clampToHeight and Scene#clampToHeightMostDetailed functions are supported.
See:

completeMorphOnUserInput : boolean

Determines whether or not to instantly complete the scene transition animation on user input.
Default Value: true

debugCommandFilter : function

This property is for debugging only; it is not for production use.

A function that determines what commands are executed. As shown in the examples below, the function receives the command's owner as an argument, and returns a boolean indicating if the command should be executed.

The default is undefined, indicating that all commands are executed.

Default Value: undefined
Example:
// Do not execute any commands.
scene.debugCommandFilter = function(command) {
    return false;
};

// Execute only the billboard's commands.  That is, only draw the billboard.
const billboards = new Cesium.BillboardCollection();
scene.debugCommandFilter = function(command) {
    return command.owner === billboards;
};

readonly debugFrustumStatistics : object

This property is for debugging only; it is not for production use.

When Scene.debugShowFrustums is true, this contains properties with statistics about the number of command execute per frustum. totalCommands is the total number of commands executed, ignoring overlap. commandsInFrustums is an array with the number of times commands are executed redundantly, e.g., how many commands overlap two or three frustums.

Default Value: undefined

debugShowCommands : boolean

This property is for debugging only; it is not for production use.

When true, commands are randomly shaded. This is useful for performance analysis to see what parts of a scene or model are command-dense and could benefit from batching.

Default Value: false

debugShowDepthFrustum : number

This property is for debugging only; it is not for production use.

Indicates which frustum will have depth information displayed.

Default Value: 1

debugShowFramesPerSecond : boolean

This property is for debugging only; it is not for production use.

Displays frames per second and time between frames.

Default Value: false

debugShowFrustumPlanes : boolean

This property is for debugging only; it is not for production use.

When true, draws outlines to show the boundaries of the camera frustums

Default Value: false

debugShowFrustums : boolean

This property is for debugging only; it is not for production use.

When true, commands are shaded based on the frustums they overlap. Commands in the closest frustum are tinted red, commands in the next closest are green, and commands in the farthest frustum are blue. If a command overlaps more than one frustum, the color components are combined, e.g., a command overlapping the first two frustums is tinted yellow.

Default Value: false

readonly drawingBufferHeight : number

The drawingBufferHeight of the underlying GL context.
See:

readonly drawingBufferWidth : number

The drawingBufferHeight of the underlying GL context.
See:

eyeSeparation : number

The eye separation distance in meters for use with cardboard or WebVR.

farToNearRatio : number

The far-to-near ratio of the multi-frustum when using a normal depth buffer.

This value is used to create the near and far values for each frustum of the multi-frustum. It is only used when Scene#logarithmicDepthBuffer is false. When logarithmicDepthBuffer is true, use Scene#logarithmicDepthFarToNearRatio.

Default Value: 1000.0

focalLength : number

The focal length for use when with cardboard or WebVR.
Blends the atmosphere to geometry far from the camera for horizon views. Allows for additional performance improvements by rendering less geometry and dispatching less terrain requests.
The value used for gamma correction. This is only used when rendering with high dynamic range.
Default Value: 2.2
Gets or sets the depth-test ellipsoid.
Gets the collection of ground primitives.

highDynamicRange : boolean

Whether or not to use high dynamic range rendering.
Default Value: false

readonly highDynamicRangeSupported : boolean

Whether or not high dynamic range rendering is supported.
Default Value: true

readonly id : string

Gets the unique identifier for this scene.
Gets the collection of image layers that will be rendered on the globe.

invertClassification : boolean

When false, 3D Tiles will render normally. When true, classified 3D Tile geometry will render normally and unclassified 3D Tile geometry will render with the color multiplied by Scene#invertClassificationColor.
Default Value: false

invertClassificationColor : Color

The highlight color of unclassified 3D Tile geometry when Scene#invertClassification is true.

When the color's alpha is less than 1.0, the unclassified portions of the 3D Tiles will not blend correctly with the classified positions of the 3D Tiles.

Also, when the color's alpha is less than 1.0, the WEBGL_depth_texture and EXT_frag_depth WebGL extensions must be supported.

Default Value: Color.WHITE

readonly invertClassificationSupported : boolean

Returns true if the Scene#invertClassification is supported.
See:

readonly lastRenderTime : JulianDate

Gets the simulation time when the scene was last rendered. Returns undefined if the scene has not yet been rendered.
The light source for shading. Defaults to a directional light from the Sun.

logarithmicDepthBuffer : boolean

Whether or not to use a logarithmic depth buffer. Enabling this option will allow for less frustums in the multi-frustum, increasing performance. This property relies on fragmentDepth being supported.

logarithmicDepthFarToNearRatio : number

The far-to-near ratio of the multi-frustum when using a logarithmic depth buffer.

This value is used to create the near and far values for each frustum of the multi-frustum. It is only used when Scene#logarithmicDepthBuffer is true. When logarithmicDepthBuffer is false, use Scene#farToNearRatio.

Default Value: 1e9
Determines if the 2D map is rotatable or can be scrolled infinitely in the horizontal direction.
Get the map projection to use in 2D and Columbus View modes.
Default Value: new GeographicProjection()

readonly maximumAliasedLineWidth : number

The maximum aliased line width, in pixels, supported by this WebGL implementation. It will be at least one.
See:
  • glGet with ALIASED_LINE_WIDTH_RANGE.

readonly maximumCubeMapSize : number

The maximum length in pixels of one edge of a cube map, supported by this WebGL implementation. It will be at least 16.
See:
  • glGet with GL_MAX_CUBE_MAP_TEXTURE_SIZE.

maximumRenderTimeChange : number

If Scene#requestRenderMode is true, this value defines the maximum change in simulation time allowed before a render is requested. Lower values increase the number of frames rendered and higher values decrease the number of frames rendered. If undefined, changes to the simulation time will never request a render. This value impacts the rate of rendering for changes in the scene like lighting, entity property updates, and animations.
Default Value: 0.0
See:

minimumDisableDepthTestDistance : number

The distance from the camera at which to disable the depth test of billboards, labels and points to, for example, prevent clipping against terrain. When set to zero, the depth test should always be applied. When less than zero, the depth test should never be applied. Setting the disableDepthTestDistance property of a billboard, label or point will override this value.
Default Value: 0.0
Gets or sets the current mode of the scene.
Default Value: SceneMode.SCENE3D
The Moon
Default Value: undefined
The event fired at the completion of a scene transition.
Default Value: Event()
The event fired at the beginning of a scene transition.
Default Value: Event()
The current morph transition time between 2D/Columbus View and 3D, with 0.0 being 2D or Columbus View and 1.0 being 3D.
Default Value: 1.0

msaaSamples : number

The sample rate of multisample antialiasing (values greater than 1 enable MSAA).
Default Value: 1

readonly msaaSupported : boolean

Returns true if the Scene's context supports MSAA.

nearToFarDistance2D : number

Determines the uniform depth size in meters of each frustum of the multifrustum in 2D. If a primitive or model close to the surface shows z-fighting, decreasing this will eliminate the artifact, but decrease performance. On the other hand, increasing this will increase performance but may cause z-fighting among primitives close to the surface.
Default Value: 1.75e6

readonly orderIndependentTranslucency : boolean

Gets whether or not the scene has order independent translucency enabled. Note that this only reflects the original construction option, and there are other factors that could prevent OIT from functioning on a given system configuration.

outputHighDynamicRange : Boolean

是否使用浮点数纹理保存 HDR 值
Default Value: false

readonly pickPositionSupported : boolean

Returns true if the Scene#pickPosition function is supported.
See:

pickTranslucentDepth : boolean

When true, enables picking translucent geometry using the depth buffer. Note that Scene#useDepthPicking must also be true for enabling this to work.

There is a decrease in performance when enabled. There are extra draw calls to write depth for translucent geometry.

Default Value: false
Example:
// picking the position of a translucent primitive
viewer.screenSpaceEventHandler.setInputAction(function onLeftClick(movement) {
     const pickedFeature = viewer.scene.pick(movement.position);
     if (!Cesium.defined(pickedFeature)) {
         // nothing picked
         return;
     }
     const worldPosition = viewer.scene.pickPosition(movement.position);
}, Cesium.ScreenSpaceEventType.LEFT_CLICK);
Post processing effects applied to the final render.
Gets the event that will be raised immediately after the scene is rendered. Subscribers to the event receive the Scene instance as the first parameter and the current time as the second parameter.
See:
Gets the event that will be raised immediately after the scene is updated and before the scene is rendered. Subscribers to the event receive the Scene instance as the first parameter and the current time as the second parameter.
See:
Gets the event that will be raised after the scene is updated and immediately before the scene is rendered. Subscribers to the event receive the Scene instance as the first parameter and the current time as the second parameter.
See:
Gets the event that will be raised before the scene is updated or rendered. Subscribers to the event receive the Scene instance as the first parameter and the current time as the second parameter.
See:
Gets the collection of primitives.

readonly renderError : Event

Gets the event that will be raised when an error is thrown inside the render function. The Scene instance and the thrown error are the only two parameters passed to the event handler. By default, errors are not rethrown after this event is raised, but that can be changed by setting the rethrowRenderErrors property.

requestRenderMode : boolean

When true, rendering a frame will only occur when needed as determined by changes within the scene. Enabling improves performance of the application, but requires using Scene#requestRender to render a new frame explicitly in this mode. This will be necessary in many cases after making changes to the scene in other parts of the API.
Default Value: false
See:

rethrowRenderErrors : boolean

Exceptions occurring in render are always caught in order to raise the renderError event. If this property is true, the error is rethrown after the event is raised. If this property is false, the render function returns normally after raising the event.
Default Value: false

readonly sampleHeightSupported : boolean

Returns true if the Scene#sampleHeight and Scene#sampleHeightMostDetailed functions are supported.
See:

readonly scene3DOnly : boolean

Gets whether or not the scene is optimized for 3D only viewing.

readonly screenSpaceCameraController : ScreenSpaceCameraController

Gets the controller for camera input handling.
The shadow map for the scene's light source. When enabled, models, primitives, and the globe may cast and receive shadows.
The sky atmosphere drawn around the globe.
Default Value: undefined
The SkyBox used to draw the stars.
Default Value: undefined
See:

smartHDRSupported : Boolean

检查是否支持自定义的 HDR 渲染。
See:

specularEnvironmentMaps : string

The url to the KTX2 file containing the specular environment map and convoluted mipmaps for image-based lighting of PBR models.

readonly specularEnvironmentMapsSupported : boolean

Returns true if specular environment maps are supported.
See:

sphericalHarmonicCoefficients : Array.<Cartesian3>

The spherical harmonic coefficients for image-based lighting of PBR models.

splitPosition : number

Gets or sets the position of the splitter within the viewport. Valid values are between 0.0 and 1.0.
超采样抗锯齿(Supersampling Anti-Aliasing)渲染器。如果开启,则使用超采样的方式来渲染场景(传统渲染器是单采样), 可以改善锯齿问题,但性能开销会增大。
Example:
scene.ssaaRenderer.enable = true;
scene.ssaaRenderer.sampleLevel = 2;
The Sun.
Default Value: undefined
Uses a bloom filter on the sun when enabled.
Default Value: true
The terrain provider providing surface geometry for the globe.

readonly terrainProviderChanged : Event

Gets an event that's raised when the terrain provider is changed

tileReduceResolution : Boolean

地形及影像的视锥体内剔除,开启会减少远处的瓦片数据和级别
Default Value: false

useDepthPicking : boolean

When true, enables picking using the depth buffer.
Default Value: true

useFrustumClipping : Boolean

视锥体内强剔除3dtiles数据,开启会减少远处的瓦片数据和级别
Default Value: false

useSmartHDR : Boolean

是否使用自定义的 HDR 渲染。
Default Value: false
See:
When true, splits the scene into two viewports with steroscopic views for the left and right eyes. Used for cardboard and WebVR.
Default Value: false

Methods

cartesianToCanvasCoordinates(position, result)Cartesian2

Transforms a position in cartesian coordinates to canvas coordinates. This is commonly used to place an HTML element at the same screen position as an object in the scene.
Name Type Description
position Cartesian3 The position in cartesian coordinates.
result Cartesian2 optional An optional object to return the input position transformed to canvas coordinates.
Returns:
The modified result parameter or a new Cartesian2 instance if one was not provided. This may be undefined if the input position is near the center of the ellipsoid.
Example:
// Output the canvas position of longitude/latitude (0, 0) every time the mouse moves.
const scene = widget.scene;
const ellipsoid = scene.globe.ellipsoid;
const position = Cesium.Cartesian3.fromDegrees(0.0, 0.0);
const handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
handler.setInputAction(function(movement) {
    console.log(scene.cartesianToCanvasCoordinates(position));
}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

clampToHeight(cartesian, objectsToExclude, width, result)Cartesian3

Clamps the given cartesian position to the scene geometry along the geodetic surface normal. Returns the clamped position or undefined if there was no scene geometry to clamp to. May be used to clamp objects to the globe, 3D Tiles, or primitives in the scene.

This function only clamps to globe tiles and 3D Tiles that are rendered in the current view. Clamps to all other primitives regardless of their visibility.

Name Type Default Description
cartesian Cartesian3 The cartesian position.
objectsToExclude Array.<Object> optional A list of primitives, entities, or 3D Tiles features to not clamp to.
width number 0.1 optional Width of the intersection volume in meters.
result Cartesian3 optional An optional object to return the clamped position.
Returns:
The modified result parameter or a new Cartesian3 instance if one was not provided. This may be undefined if there was no scene geometry to clamp to.
Throws:
  • DeveloperError : clampToHeight is only supported in 3D mode.
  • DeveloperError : clampToHeight requires depth texture support. Check clampToHeightSupported.
Example:
// Clamp an entity to the underlying scene geometry
const position = entity.position.getValue(Cesium.JulianDate.now());
entity.position = viewer.scene.clampToHeight(position);
See:

clampToHeightMostDetailed(cartesians, objectsToExclude, width)Promise.<Array.<Cartesian3>>

Initiates an asynchronous Scene#clampToHeight query for an array of Cartesian3 positions using the maximum level of detail for 3D Tilesets in the scene. Returns a promise that is resolved when the query completes. Each position is modified in place. If a position cannot be clamped because no geometry can be sampled at that location, or another error occurs, the element in the array is set to undefined.
Name Type Default Description
cartesians Array.<Cartesian3> The cartesian positions to update with clamped positions.
objectsToExclude Array.<Object> optional A list of primitives, entities, or 3D Tiles features to not clamp to.
width number 0.1 optional Width of the intersection volume in meters.
Returns:
A promise that resolves to the provided list of positions when the query has completed.
Throws:
  • DeveloperError : clampToHeightMostDetailed is only supported in 3D mode.
  • DeveloperError : clampToHeightMostDetailed requires depth texture support. Check clampToHeightSupported.
Example:
const cartesians = [
    entities[0].position.getValue(Cesium.JulianDate.now()),
    entities[1].position.getValue(Cesium.JulianDate.now())
];
const promise = viewer.scene.clampToHeightMostDetailed(cartesians);
promise.then(function(updatedCartesians) {
    entities[0].position = updatedCartesians[0];
    entities[1].position = updatedCartesians[1];
}
See:
Instantly completes an active transition.
Destroys the WebGL resources held by this object. Destroying an object allows for deterministic release of WebGL resources, instead of relying on the garbage collector to destroy this object.

Once an object is destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception. Therefore, assign the return value (undefined) to the object as done in the example.
Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
Example:
scene = scene && scene.destroy();
See:

drillPick(windowPosition, limit, width, height)Array.<any>

Returns a list of objects, each containing a `primitive` property, for all primitives at a particular window coordinate position. Other properties may also be set depending on the type of primitive and may be used to further identify the picked object. The primitives in the list are ordered by their visual order in the scene (front to back).
Name Type Default Description
windowPosition Cartesian2 Window coordinates to perform picking on.
limit number optional If supplied, stop drilling after collecting this many picks.
width number 3 optional Width of the pick rectangle.
height number 3 optional Height of the pick rectangle.
Returns:
Array of objects, each containing 1 picked primitives.
Throws:
Example:
const pickedObjects = scene.drillPick(new Cesium.Cartesian2(100.0, 200.0));
See:

getCompressedTextureFormatSupported(format)boolean

Determines if a compressed texture format is supported.
Name Type Description
format string The texture format. May be the name of the format or the WebGL extension name, e.g. s3tc or WEBGL_compressed_texture_s3tc.
Returns:
Whether or not the format is supported.

isDestroyed()boolean

Returns true if this object was destroyed; otherwise, false.

If this object was destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception.
Returns:
true if this object was destroyed; otherwise, false.
See:

morphTo2D(duration)

Asynchronously transitions the scene to 2D.
Name Type Default Description
duration number 2.0 optional The amount of time, in seconds, for transition animations to complete.

morphTo3D(duration)

Asynchronously transitions the scene to 3D.
Name Type Default Description
duration number 2.0 optional The amount of time, in seconds, for transition animations to complete.

morphToColumbusView(duration)

Asynchronously transitions the scene to Columbus View.
Name Type Default Description
duration number 2.0 optional The amount of time, in seconds, for transition animations to complete.

pick(windowPosition, width, height)object

Returns an object with a `primitive` property that contains the first (top) primitive in the scene at a particular window coordinate or undefined if nothing is at the location. Other properties may potentially be set depending on the type of primitive and may be used to further identify the picked object.

When a feature of a 3D Tiles tileset is picked, pick returns a Cesium3DTileFeature object.

Name Type Default Description
windowPosition Cartesian2 Window coordinates to perform picking on.
width number 3 optional Width of the pick rectangle.
height number 3 optional Height of the pick rectangle.
Returns:
Object containing the picked primitive.
Example:
// On mouse over, color the feature yellow.
handler.setInputAction(function(movement) {
    const feature = scene.pick(movement.endPosition);
    if (feature instanceof Cesium.Cesium3DTileFeature) {
        feature.color = Cesium.Color.YELLOW;
    }
}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

pickPosition(windowPosition, result)Cartesian3

Returns the cartesian position reconstructed from the depth buffer and window position.

The position reconstructed from the depth buffer in 2D may be slightly different from those reconstructed in 3D and Columbus view. This is caused by the difference in the distribution of depth values of perspective and orthographic projection.

Set Scene#pickTranslucentDepth to true to include the depth of translucent primitives; otherwise, this essentially picks through translucent primitives.

Name Type Description
windowPosition Cartesian2 Window coordinates to perform picking on.
result Cartesian3 optional The object on which to restore the result.
Returns:
The cartesian position.
Throws:
  • DeveloperError : Picking from the depth buffer is not supported. Check pickPositionSupported.
Update and render the scene. It is usually not necessary to call this function directly because CesiumWidget will do it automatically.
Name Type Description
time JulianDate optional The simulation time at which to render.
Requests a new rendered frame when Scene#requestRenderMode is set to true. The render rate will not exceed the CesiumWidget#targetFrameRate.
See:

sampleHeight(position, objectsToExclude, width)number

Returns the height of scene geometry at the given cartographic position or undefined if there was no scene geometry to sample height from. The height of the input position is ignored. May be used to clamp objects to the globe, 3D Tiles, or primitives in the scene.

This function only samples height from globe tiles and 3D Tiles that are rendered in the current view. Samples height from all other primitives regardless of their visibility.

Name Type Default Description
position Cartographic The cartographic position to sample height from.
objectsToExclude Array.<Object> optional A list of primitives, entities, or 3D Tiles features to not sample height from.
width number 0.1 optional Width of the intersection volume in meters.
Returns:
The height. This may be undefined if there was no scene geometry to sample height from.
Throws:
  • DeveloperError : sampleHeight is only supported in 3D mode.
  • DeveloperError : sampleHeight requires depth texture support. Check sampleHeightSupported.
Example:
const position = new Cesium.Cartographic(-1.31968, 0.698874);
const height = viewer.scene.sampleHeight(position);
console.log(height);
See:

sampleHeightMostDetailed(positions, objectsToExclude, width)Promise.<Array.<Cartographic>>

Initiates an asynchronous Scene#sampleHeight query for an array of Cartographic positions using the maximum level of detail for 3D Tilesets in the scene. The height of the input positions is ignored. Returns a promise that is resolved when the query completes. Each point height is modified in place. If a height cannot be determined because no geometry can be sampled at that location, or another error occurs, the height is set to undefined.
Name Type Default Description
positions Array.<Cartographic> The cartographic positions to update with sampled heights.
objectsToExclude Array.<Object> optional A list of primitives, entities, or 3D Tiles features to not sample height from.
width number 0.1 optional Width of the intersection volume in meters.
Returns:
A promise that resolves to the provided list of positions when the query has completed.
Throws:
  • DeveloperError : sampleHeightMostDetailed is only supported in 3D mode.
  • DeveloperError : sampleHeightMostDetailed requires depth texture support. Check sampleHeightSupported.
Example:
const positions = [
    new Cesium.Cartographic(-1.31968, 0.69887),
    new Cesium.Cartographic(-1.10489, 0.83923)
];
const promise = viewer.scene.sampleHeightMostDetailed(positions);
promise.then(function(updatedPosition) {
    // positions[0].height and positions[1].height have been updated.
    // updatedPositions is just a reference to positions.
}
See:
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