As I had long suspected, building large hierarchies is fiendishly
expensive (at least O(N^2)). However, this is because the hierarchies
are structured such that adding high-level nodes results in a lot of
copying due to the flattened (breadth-first) layout (which does make for
excellent breadth-first performance when working with a hierarchy).
Using tree mode allows adding new nodes to be O(1) (I guess O(N) for the
size of the sub-tree being added, but that's not supported yet) and
costs only an additional 8 bytes per node. Switching from flat mode to
tree mode is very cheap as only the additional tree-related indices need
to be fixed up (they're almost entirely ignored in flat mode). Switching
from tree to flat mode is a little more expensive as the entire tree
needs to be copied, but it seems to be an O(N) (size of the tree).
With this, building the style editor window went from about 25% to about
5% (and most of that is realloc!), with a 1.3% cost for switching from
tree mode to flat mode.
There's still a lot of work to do (supporting removal and tree inserts).
I'm not sure just what was going on other than *other* components were
getting double-removed when the hierarchy reference component was
removed when the entity was being deleted. This might even prevent
issues with removing the hierarchy from an entity that's not being
deleted as the pre-invalidation prevents the removal from deleting the
entity.
The hierarchy leak was particularly troublesome to fix, but now the
hierarchies get updated (and freed) automatically just by removing the
hierarchy reference component from the entity. I suspect there will be
issues with entities that are on multiple hierarchies, but I'll sort
that out later.
There's now a main ecs.h file that includes the sub-system headers,
removing the need to explicitly include several header files, but the
sub-systems are a less cluttered.
This means that the component id used for hierarchy references must be
passed to Hierarchy_New and Hierarchy_Copy, but does all an entity to
have more than one hierarchy, which is useful for canvases (hierarchies
of views) in the 3d world (the canvas root would have a 3d hierarchy
reference and a 2d (view) hierarchy reference).
In the end, it was removal of the old entries that corrupted the parent
indices. Very nicely, most of the fixes involved removing code. Taking
advantage of the ECS to debug the hierarchies was fun, and the resulting
colorized entity names helped no end.
This improves the behavior of hierarchies when self-inserting, but nq's
sbar still crashes when trying to do so. However, its tree is a fair bit
more complex than the test case (that does pass now), so I need to try
to replicate the important parts of the tree with fewer objects (180 is
too many to work with).
Its updates to the various indices were out, but this was missed due to
the tests being wrong. I wonder if I got interrupted while working on
them last and just assumed the removals were correct. This improves
sbar's behavior, but it's still wrong when pulling the armory view out
of the inventory. Very unsure what's going on, but the various indices
look ok, as do the view positions.
The hierarchy-specific tests from the transform tests have been moved
into the ecs tests and the transform tests renamed appropriately. As
part of the process, hierarchies can now have a null type (ie, no
additional components maintained by the hierarchy). This should make
sorting out the issues highlighted by sbar a bit easier.
It should have always been here, but when I first created the hierarchy
and transform objects, I didn't know where things would go. Having two
chunks of code for setting an entity's parent was too already too much,
and I expect to have other hierarchy types. Doesn't fix the issues
encountered with sbar, of course.
As an implementation detail, inserting null hierarchies (src hierarchy
is null) is supported for ease of hierarchy construction from data. No
component data is copied, only the child and parent indices and counts
are updated.
While the libraries are probably getting a little out of hand, the
separation into its own directory is probably a good thing as an ECS
should not be tied to scenes. This should make the ECS more generally
useful.
