itaps-parallel Mesh Instances

[Jason Kraftcheck]

Mark Miller wrote:
> This is consistent with my understanding of what Jason proposed in the way
> of a multi-plexor also based on my review of the code example he sent.
> 
> And, doesn't this mean that 'co-existance' cannot be solved by a multiplexor?
> Or, does it only mean that it cannot be solved by the currently proposed
> multiplexor?

Given the current C interface, an entity is uniquely identified by the
tuple {mesh_instance,entity_handle}.  If the multiplexer where to present
the fiction of a single mesh_instance combining two real mesh instances,
it would need some mechanism to determine the mesh_instance from the
entity_handle.  Given that a specific handle value may identify valid
entities in both interfaces, it would be necessary for the multiplexer to
create its own handle space and map from each 'virtual' handle to a real
handle and mesh_instance.  I'd probably implement this using integer
handle values, where the highest bits index into an array of
mesh_instances and the lower bits index into a map to the handle in the
mesh instance.

This seems expensive.  Why would anyone want to do this?

- jason