Why you should use a basic cube for your Root Prim

Whatever works for you is ultimately fine, but there are many good reasons to use an invisible cube for your root prim.

  • Your invisible root cube can be positioned anywhere in the vehicle to adjust your steering and banking, as the center of the root prim is the pivot point for rotational forces applied to the vehicle. Adjust your up/down and forward/back position of the root to make changes to your steering and banking.
  • Your root cube angle can be adjusted to get your vehicle perfectly level, and you are not stuck working around the 0 rotation of a sculpted/mesh part
  • Your root cube should be rezzed by you and will show the object as having you as the creator. If you buy pre-made mesh components or map-free sculpties and use those as a root prim, the creator of that object will be shown as the vehicle creator. That's why you should always be the one to rez your own root prim.
  • Using the newer mesh physics for vehicles with mesh or builds over 32 prims, your root prim will always be solid/convex hull. Convex hull shaped prims use up extra physics allotment, the more complex the shape the more land impact they use. Using a basic cube for the root will use the least amount of physics allotment as convex hull shape.
  • An invisible root prim allows you to resize the prim as needed to affect handling and physics. You are not constrained to part size. This is especially important when using mesh physics, as the only prims to have weight and mass are ones set to solid/convex hull. Increasing your solid/convex hull root size will give you much better weight and physics reaction to work with, and can act as an invisible solid shield to prevent your more delicate parts from getting stuck on objects.
  • It is important your root prim is not too tiny or narrow, as it will be applying less rotational torque to the rest of the linkset. An invisible cube has no visible restrictions on size and position.