ローカル空間にあるアニメーションクリップの AABB をアタッチします。
It is precomputed on import for imported models/animations based on the meshes that this animation clip affects. This bounding box is specific to the mesh(es) that this clip is attached to during import, i.e. this means that it is calculated based on the file that is part of and on the "Model" file if you're using Model@Animation notation.