A class containing utility functions for [page:BufferGeometry BufferGeometry] instances.
geometry -- A [page:BufferGeometry BufferGeometry] instance, which must have index, position, normal, and uv attributes.
Calculates and adds tangent attribute to a geometry.
geometries -- Array of [page:BufferGeometry BufferGeometry] instances.
Merges a set of geometries into a single instance. All geometries must have compatible attributes.
If merge does not succeed, the method returns null.
attributes -- Array of [page:BufferAttribute BufferAttribute] instances.
Merges a set of attributes into a single instance. All attributes must have compatible properties
and types, and [page:InterleavedBufferAttribute InterleavedBufferAttributes] are not supported. If merge does not succeed, the method
returns null.