Phantasmal Site > Design > Object Grouping

Object Grouping for Phantasmal, Speculations

We'd like to have objects group up when they're all in the same area. For instance, if you drop seventeen mixed swords in a pile in the middle of the floor, we'd like to see a "pile of swords" rather than each one having its own entry. As we add opportunity for object customization (wear and tear, difference in manufacture, varying styles), this will get even more important.

A first, simple cut at the problem would simply use a single inheritance heirarchy, and each node could be marked with whether it could be used as a player-visible grouping -- "sword" would be a good one, but "iron object" would need to be marked as not player-visible, or perhaps simply given a fudge factor such that it wouldn't often be used.

However, we'd like to have multiple inheritance, not just single inheritance. A group of a shovel, ten hoes, a wheelbarrow, a thresher, and a pickaxe might be characterized by either "some farm equipment, a wheelbarrow and a pickaxe" or "some tools, a wheelbarrow and a thresher". Conceivably it could also be "some metal objects", but that's not very descriptive, so again, the "metal objects" group would be non-player-visible, or tagged such that it was very rarely chosen.

The problem with multiple inheritance is choosing how to characterize a group of objects, and doing so quite quickly. Bear in mind that two different characters (with different fields of view from their two locations) might see these objects differently. For instance, one might not see the thresher from his point of view in the hayloft, while the other might not see the pickaxe from outside the door. This group of objects (sometimes including the pickaxe and thresher) will have to simultaneously be "some farm equipment and a wheelbarrow" and "some tools and a wheelbarrow". That suggests that we need some kind of caching scheme in which we can quickly run over the structures for multiple groups of objects and determine a description.

One example scheme: for every group of four or more objects in a single location, make a group accounting object. This doesn't have to be an object in the MUD sense, but the location containing the objects must be able to easily find and use it. This group accounting object (GAO) will lazily categorize the objects into the group heirarchy when requested to. It must be very quick to merge two or more of these GAOs into a new combined GAO -- for instance, the GAOs for the hayloft, the main floor of the barn and the area just outside the barn door will frequently be merged because they will frequently be visible from the same locations.