Billboard

查阅Mars3D API

internal constructor new Cesium.Billboard(options, billboardCollection)

engine/Source/Scene/Billboard.js 95

A billboard is created and its initial properties are set by calling BillboardCollection#add. Do not call the constructor directly.

A viewport-aligned image positioned in the 3D scene, that is created and rendered using a BillboardCollection.

Example billboards

Performance:

Reading a property, e.g., Billboard#show, is constant time. Assigning to a property is constant time but results in CPU to GPU traffic when BillboardCollection#update is called. The per-billboard traffic is the same regardless of how many properties were updated. If most billboards in a collection need to be updated, it may be more efficient to clear the collection with BillboardCollection#removeAll and add new billboards instead of modifying each one.

参数名称	类型	描述信息
options	Billboard.ConstructorOptions	Object describing initialization options
billboardCollection	BillboardCollection	Instance of BillboardCollection

Throws:

• DeveloperError : scaleByDistance.far must be greater than scaleByDistance.near
• DeveloperError : translucencyByDistance.far must be greater than translucencyByDistance.near
• DeveloperError : pixelOffsetScaleByDistance.far must be greater than pixelOffsetScaleByDistance.near
• DeveloperError : distanceDisplayCondition.far must be greater than distanceDisplayCondition.near

Demo:

• Cesium Sandcastle Billboard Demo

参考:

• BillboardCollection
• BillboardCollection#add
• Label

成员(属性)

使用示例s:

// Example 1.
// Have the billboard up vector point north
billboard.alignedAxis = Cesium.Cartesian3.UNIT_Z;

// Example 2.
// Have the billboard point east.
billboard.alignedAxis = Cesium.Cartesian3.UNIT_Z;
billboard.rotation = -Cesium.Math.PI_OVER_TWO;

// Example 3.
// Reset the aligned axis
billboard.alignedAxis = Cesium.Cartesian3.ZERO;

Gets or sets the color that is multiplied with the billboard's texture. This has two common use cases. First, the same white texture may be used by many different billboards, each with a different color, to create colored billboards. Second, the color's alpha component can be used to make the billboard translucent as shown below. An alpha of 0.0 makes the billboard transparent, and 1.0 makes the billboard opaque.

default

alpha : 0.5

The red, green, blue, and alpha values are indicated by value's red, green, blue, and alpha properties as shown in Example 1. These components range from 0.0 (no intensity) to 1.0 (full intensity).

使用示例s:

// Example 1. Assign yellow.
b.color = Cesium.Color.YELLOW;

// Example 2. Make a billboard 50% translucent.
b.color = new Cesium.Color(1.0, 1.0, 1.0, 0.5);

默认值: undefined

Gets or sets the 3D Cartesian offset applied to this billboard in eye coordinates. Eye coordinates is a left-handed coordinate system, where x points towards the viewer's right, y points up, and z points into the screen. Eye coordinates use the same scale as world and model coordinates, which is typically meters.

An eye offset is commonly used to arrange multiple billboards or objects at the same position, e.g., to arrange a billboard above its corresponding 3D model.

Below, the billboard is positioned at the center of the Earth but an eye offset makes it always appear on top of the Earth regardless of the viewer's or Earth's orientation.

b.eyeOffset = new Cartesian3(0.0, 8000000.0, 0.0);

默认值: HeightReference.NONE

Gets or sets the horizontal origin of this billboard, which determines if the billboard is to the left, center, or right of its anchor position.

使用示例:

// Use a bottom, left origin
b.horizontalOrigin = Cesium.HorizontalOrigin.LEFT;
b.verticalOrigin = Cesium.VerticalOrigin.BOTTOM;

使用示例:

// load an image from a URL
b.image = 'some/image/url.png';

// assuming b1 and b2 are billboards in the same billboard collection,
// use the same image for both billboards.
b2.image = b1.image;

Gets or sets the pixel offset in screen space from the origin of this billboard. This is commonly used to align multiple billboards and labels at the same position, e.g., an image and text. The screen space origin is the top, left corner of the canvas; x increases from left to right, and y increases from top to bottom.

default

b.pixeloffset = new Cartesian2(50, 25);

The billboard's origin is indicated by the yellow point.

使用示例s:

// Example 1.
// Set a billboard's pixel offset scale to 0.0 when the
// camera is 1500 meters from the billboard and scale pixel offset to 10.0 pixels
// in the y direction the camera distance approaches 8.0e6 meters.
b.pixelOffset = new Cesium.Cartesian2(0.0, 1.0);
b.pixelOffsetScaleByDistance = new Cesium.NearFarScalar(1.5e2, 0.0, 8.0e6, 10.0);

// Example 2.
// disable pixel offset by distance
b.pixelOffsetScaleByDistance = undefined;

默认值: false

Gets or sets the uniform scale that is multiplied with the billboard's image size in pixels. A scale of 1.0 does not change the size of the billboard; a scale greater than 1.0 enlarges the billboard; a positive scale less than 1.0 shrinks the billboard.

From left to right in the above image, the scales are 0.5, 1.0, and 2.0.

使用示例s:

// Example 1.
// Set a billboard's scaleByDistance to scale by 1.5 when the
// camera is 1500 meters from the billboard and disappear as
// the camera distance approaches 8.0e6 meters.
b.scaleByDistance = new Cesium.NearFarScalar(1.5e2, 1.5, 8.0e6, 0.0);

// Example 2.
// disable scaling by distance
b.scaleByDistance = undefined;

默认值: true

默认值: false

默认值: SplitDirection.NONE

使用示例s:

// Example 1.
// Set a billboard's translucency to 1.0 when the
// camera is 1500 meters from the billboard and disappear as
// the camera distance approaches 8.0e6 meters.
b.translucencyByDistance = new Cesium.NearFarScalar(1.5e2, 1.0, 8.0e6, 0.0);

// Example 2.
// disable translucency by distance
b.translucencyByDistance = undefined;

Gets or sets the vertical origin of this billboard, which determines if the billboard is to the above, below, or at the center of its anchor position.

使用示例:

// Use a bottom, left origin
b.horizontalOrigin = Cesium.HorizontalOrigin.LEFT;
b.verticalOrigin = Cesium.VerticalOrigin.BOTTOM;

方法

返回值:

Throws:

• DeveloperError : Billboard must be in a collection.

使用示例:

console.log(b.computeScreenSpacePosition(scene).toString());

参考:

• Billboard#eyeOffset
• Billboard#pixelOffset

返回值:

使用示例:

// create a billboard image dynamically
function drawImage(id) {
  // create and draw an image using a canvas
  const canvas = document.createElement('canvas');
  const context2D = canvas.getContext('2d');
  // ... draw image
  return canvas;
}
// drawImage will be called to create the texture
b.setImage('myImage', drawImage);

// subsequent billboards created in the same collection using the same id will use the existing
// texture, without the need to create the canvas or draw the image
b2.setImage('myImage', drawImage);

Throws:

• RuntimeError : image with id must be in the atlas

定义的类型

属性:

属性名称	类型	可选	默认值	描述信息
position	Cartesian3			The cartesian position of the billboard.
id	*	<可选>		A user-defined object to return when the billboard is picked with Scene#pick.
show	boolean	<可选>	true	Determines if this billboard will be shown.
image	string | HTMLCanvasElement	<可选>		A loaded HTMLImageElement, ImageData, or a url to an image to use for the billboard.
scale	number	<可选>	1.0	A number specifying the uniform scale that is multiplied with the billboard's image size in pixels.
pixelOffset	Cartesian2	<可选>	Cartesian2.ZERO	A Cartesian2 Specifying the pixel offset in screen space from the origin of this billboard.
eyeOffset	Cartesian3	<可选>	Cartesian3.ZERO	A Cartesian3 Specifying the 3D Cartesian offset applied to this billboard in eye coordinates.
horizontalOrigin	HorizontalOrigin	<可选>	HorizontalOrigin.CENTER	A HorizontalOrigin Specifying the horizontal origin of this billboard.
verticalOrigin	VerticalOrigin	<可选>	VerticalOrigin.CENTER	A VerticalOrigin Specifying the vertical origin of this billboard.
heightReference	HeightReference	<可选>	HeightReference.NONE	A HeightReference Specifying the height reference of this billboard.
color	Color	<可选>	Color.WHITE	A Color Specifying the color that is multiplied with the billboard's texture.
rotation	number	<可选>	0	A number specifying the rotation angle in radians.
alignedAxis	Cartesian3	<可选>	Cartesian3.ZERO	A Cartesian3 Specifying the aligned axis in world space.
sizeInMeters	boolean	<可选>		A boolean specifying if the billboard size is in meters or pixels.
width	number	<可选>		A number specifying the width of the billboard. If undefined, the image width will be used.
height	number	<可选>		A number specifying the height of the billboard. If undefined, the image height will be used.
scaleByDistance	NearFarScalar	<可选>		A NearFarScalar Specifying near and far scaling properties of a Billboard based on the billboard's distance from the camera.
translucencyByDistance	NearFarScalar	<可选>		A NearFarScalar Specifying near and far translucency properties of a Billboard based on the billboard's distance from the camera.
pixelOffsetScaleByDistance	NearFarScalar	<可选>		A NearFarScalar Specifying near and far pixel offset scaling properties of a Billboard based on the billboard's distance from the camera.
imageSubRegion	BoundingRectangle	<可选>		A BoundingRectangle Specifying the sub-region of the image to use for the billboard, rather than the entire image.
distanceDisplayCondition	DistanceDisplayCondition	<可选>		A DistanceDisplayCondition Specifying the distance from the camera at which this billboard will be displayed.
disableDepthTestDistance	number	<可选>		A number specifying the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain.
splitDirection	SplitDirection	<可选>		A SplitDirection Specifying the split property of the billboard.

返回值: