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ThreeJS BufferAttribute
2022-04-29 10:06:44

ThreeJS BufferAttribute

This class stores data for an attribute associated with a BufferGeometry (such as vertex positions, face indices, normals, colours, UVs, and any custom attributes), allowing for more efficient data passing to the GPU.

Data is stored as vectors of any length (defined by itemSize), and in general, if an index is passed in, it is automatically multiplied by the vector length in the methods outlined below.

Constructor

BufferAttribute( array : TypedArray, itemSize : Integer, normalized : Boolean )

array -- Must be a TypedArray. Used to instantiate the buffer.

This array should have

itemSize * numVertices

elements, where numVertices is the number of vertices in the associated BufferGeometry.

itemSize -- the number of values of the array that should be associated with a particular vertex.

normalized -- (optional) Applies to integer data only. Indicates how the underlying data in the buffer maps to the values in the GLSL code.

Properties

.array : TypedArray

The array holding data stored in the buffer.

.count : Integer

Stores the array's length divided by the itemSize.

If the buffer is storing a 3-component vector (such as a position, normal, or color), then this will count the number of such vectors stored.

.itemSize : Integer

The length of vectors that are being stored in the array.

.name : String

Optional name for this attribute instance. Default is an empty string.

.needsUpdate : Boolean

Flag to indicate that this attribute has changed and should be re-sent to the GPU. Set this to true when you modify the value of the array.

Setting this to true also increments the version.

.normalized : Boolean

Indicates how the underlying data in the buffer maps to the values in the GLSL shader code. See the constructor above for details.

.onUploadCallback : Function

A callback function that is executed after the Renderer has transferred the attribute array data to the GPU.

.updateRange : Object

Object containing:

offset: Default is 0. Position at which to start update.

count: Default is -1, which means don't use update ranges.

This can be used to only update some components of stored vectors (for example, just the component related to color).

.usage : Usage

Defines the intended usage pattern of the data store for optimization purposes. Corresponds to the usage parameter of WebGLRenderingContext.bufferData(). Default is StaticDrawUsage. See usage constants for all possible values.

.version : Integer

A version number, incremented every time the needsUpdate property is set to true.

Methods

.applyMatrix3 ( m : Matrix3 ) : this

Applies matrix m to every Vector3 element of this BufferAttribute.

.applyMatrix4 ( m : Matrix4 ) : this

Applies matrix m to every Vector3 element of this BufferAttribute.

.applyNormalMatrix ( m : Matrix3 ) : this

Applies normal matrix m to every Vector3 element of this BufferAttribute.

.transformDirection ( m : Matrix4 ) : this

Applies matrix m to every Vector3 element of this BufferAttribute, interpreting the elements as a direction vectors.

.clone () : BufferAttribute

Return a copy of this bufferAttribute.

.copy ( bufferAttribute : BufferAttribute ) : this

Copies another BufferAttribute to this BufferAttribute.

.copyArray ( array ) : this

Copy the array given here (which can be a normal array or TypedArray) into array.

See TypedArray.set for notes on requirements if copying a TypedArray.

.copyAt ( index1 : Integer, bufferAttribute : BufferAttribute, index2 : Integer ) : this

Copy a vector from bufferAttribute[index2] to array[index1].

.copyColorsArray ( colors : Array ) : this

Copy an array representing RGB color values into array.

.copyVector2sArray ( vectors : Array ) : this

Copy an array representing Vector2s into array.

.copyVector3sArray ( vectors : Array ) : this

Copy an array representing Vector3s into array.

.copyVector4sArray ( vectors : Array ) : this

Copy an array representing Vector4s into array.

.getX ( index : Integer ) : Number

Returns the x component of the vector at the given index.

.getY ( index : Integer ) : Number

Returns the y component of the vector at the given index.

.getZ ( index : Integer ) : Number

Returns the z component of the vector at the given index.

.getW ( index : Integer ) : Number

Returns the w component of the vector at the given index.

.onUpload ( callback : Function ) : this

Sets the value of the onUploadCallback property.

In the WebGL / Buffergeometry this is used to free memory after the buffer has been transferred to the GPU.

.set ( value : Array, offset : Integer ) : this

value -- an Array or TypedArray from which to copy values.

offset -- (optional) index of the array at which to start copying.

Calls TypedArray.set( value, offset ) on the array.

In particular, see that page for requirements on value being a TypedArray.

.setUsage ( value : Usage ) : this

Set usage to value. See usage constants for all possible input values.

.setX ( index : Integer, x : Float ) : this

Sets the x component of the vector at the given index.

.setY ( index : Integer, y : Float ) : this

Sets the y component of the vector at the given index.

.setZ ( index : Integer, z : Float ) : this

Sets the z component of the vector at the given index.

.setW ( index : Integer, w : Float ) : this

Sets the w component of the vector at the given index.

.setXY ( index : Integer, x : Float, y : Float ) : this

Sets the x and y components of the vector at the given index.

.setXYZ ( index : Integer, x : Float, y : Float, z : Float ) : this

Sets the x, y and z components of the vector at the given index.

.setXYZW ( index : Integer, x : Float, y : Float, z : Float, w : Float ) : this

Sets the x, y, z and w components of the vector at the given index.