OBB

OBB is an acronym used in different technical domains, most commonly referring to oriented bounding boxes in computer graphics and to Android expansion files used to deliver large app resources. A concise overview of these two meanings follows.

Oriented bounding box

An oriented bounding box (OBB) is a rectangular box in 2D or 3D whose faces are aligned with the object’s local coordinate axes rather than the global world axes. An OBB is defined by its center, three orthogonal axes, and extents along each axis. Because the box can rotate with the object, an OBB typically fits the object more tightly than an axis-aligned bounding box (AABB). OBBs are used in collision detection, visibility tests, and physics simulations, and they can be organized into hierarchical structures (OBB trees) to accelerate queries. Computing and testing OBBs often involve the Separating Axis Theorem and related algorithms.

Android OBB files

In Android development, OBB also stands for opaque binary blob, a container used to store large expansion resources separate from the APK. Expansion files are delivered by Google Play as ZIP-based archives with names such as main.version.package.obb and patch.version.package.obb. They are stored on the device under /Android/obb/<package-name> and accessed by apps via the APK Expansion Files API (for example, APKExpansionSupport). Each app may have a main OBB and an optional patch OBB, each up to about 2 GB, containing assets like textures, audio, or sizable data sets that would otherwise inflate the APK size.

See also

Bounding boxes, collision detection, APK expansion files.