Pre-build RBD Objects and Visual Clue

Before us diving into the others dynamics features, we need deeply understand a very important concept. That is pre-build RBD objects
In many cases (collision detection, cloth enable etc.), we need create some pre-build the RBD objects in agent memory and let our animation bones drive these internal RBD before really physical simulation. In this time, you cannot see agent perform physical behavior, but actually the physical contents are there and controlled by action.
Firstly, let's take a look at that when these pre-build RBD objects will be created and why we need them, and how can we know/detect their existence. Then we will introduce you how can you optimize and avoid our engine create these pre-build RBD objects if our scene doesn't need them.
When these conditions, these pre-build RBD will be created in agent memory:

• collide channel in input
• RBD collide check in input
• cloth enable
• partial dynamics
• body dynamics
• broken dynamics

We created them because we need these RBD to:

• collision detection
• hold cloth attach points or collide with cloth
• drive the partial dynamical chain

If there are internal pre-build RBD created, you can simply switch to the wireframe mode to check their existence. Just like the picture below, the bone with "dot/small point" is exact pre-build RBD inside its memory. Please notice there also a "cross", which will be talked about in collision detection session.

If there are internal RBD in agent, system will mark "dot" into the Bone

If collide enable, everyone has their own pre-build RBD internal

The pre-build RBD objects will take memory, so please keep check them if you're working on the scenes with physical features. If not nessecery, please make sure they will not going to be created.