There are rumors that the new Materials System will push objects that use the new materials into the Land Impact Accounting system. Some have found that when playing with Materials the Land Impact can escalate radically on physics cost. When using Alpha Masking the new materials can drive the Land Impact WAY UP. Plus a single prim, even phantom, can cost 500+ Physics LI. The image below shows a flattened sphere that costs 560 LI.
Andrew said some things that suggest items using Materials are planned to use the Land Impact Cost Accounting system. So, I would guess part of the reason we have this Alpha version viewer is to find problems they have missed. The Land Impact one is a big one.
These bugs suggest they need to consider some new possibilities for limiting the Land Impact. Andrew is thinking about a low cost class for static phantom objects.
The addition of another new item to the LI Accounting System suggests we will see more new modeling features that use the new system. It seems to be the trend at the Lab.
I think it also shows how the system sees basic prims when pushed into the LI Accounting. This may be giving us an idea of how much load prims can actually place on the system. If that is accurate, then the more the LA Accounting is used, the more efficient SL will become with time. The end results will be less lag and faster rendering.
Materials does offer the possibility to triple the amount of textures that must be loaded to render an object. I suppose it is reasonable to place some limits on the feature.
Andrew points out that the reason Phantom prims can still incur a physics cost is that they are not completely collisionless. When answering a question he said, “…because phantom doesn’t actually mean “collisionless”, at least not according to the physics engine. It actually means ‘collides with ground only.’”
There is a convex hull prim type that is completely no physics and it falls through the ground.
WARNING: This high prim Land Impact thing means it is dangerous to play with Materials any place other than a sandbox. You could end up getting large parts of a region returned.