The Dynamics Parts Info node allows you to control an individual element of a Bullet Parts object. You need to attach an Item ID node pertaining to the Parts object into Item ID on this node and an Integer node to determine the part you wish to use.
In this screenshot we show the Pyramid-shaped Null has the Nodal Motion modifier attached. When we press play on the scene, the null will jump to the Part indicated by the Integer node. We have it set to the default 1, which means the Null will jump to the middle front box. As the boxes fall, the null will match movement and rotation to the part.
- Item ID - The dynamic item in the scene that uses Parts
- Part Number - The ID of the individual part
- Polygon Index - The polygon index for the part
- Part Number - Index number of the part
- Internal Polygon - 1 if the polygon is a boundary between two parts which have not separated yet (i.e. the polygon is inside the volume, not on an outside surface), 0 otherwise. This is what you would use to clip away polygons that shouldn't be visible yet
- Part World Position - World position of the center of mass of the part
- Part World Right/Up/Forward - Right/Up/Forward vectors of the part in world coordinates. Parts start off with the same orientation as the item
- Part World Rotation - HPB rotation of the part in world
Taking the Internal Polygon output to the Surface Clip input will hide internal polygons for a fractured object in Bullet