BufferAttribute

This class stores data for an attribute (such as vertex positions, face indices, normals, colors, UVs, and any custom attributes) associated with a BufferGeometry, which allows for more efficient passing of data to the GPU. See that page for details and a usage example. When working with vector-like data, the .fromBufferAttribute(attribute, index) helper methods on Vector2, Vector3, Vector4, and Color classes may be helpful.

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. For instance, if this attribute is storing a 3-component vector (such as a position, normal, or color), then itemSize should be 3.

normalized — (optional) Applies to integer data only. Indicates how the underlying data in the buffer maps to the values in the GLSL code. For instance, if array is an instance of UInt16Array, and normalized is true, the values 0 - +65535 in the array data will be mapped to 0.0f - +1.0f in the GLSL attribute. An Int16Array (signed) would map from -32768 - +32767 to -1.0f - +1.0f. If normalized is false, the values will be converted to floats unmodified, i.e. 32767 becomes 32767.0f.

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.

# .isBufferAttribute : Boolean

Read-only flag to check if a given object is of type BufferAttribute.

# .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.

After the initial use of a buffer, its usage cannot be changed. Instead, instantiate a new one and set the desired usage before the next render.