* There's not a good accepted terminology for this kind of event, and for
historical reasons 'drawcall' has been the accepted term, even though
that can be quite confusing when a dispatch or a copy is a 'drawcall'.
* This is particularly highlighted by the event browser filters where
$draw() includes draws and dispatches, but $dispatch() only includes
dispatches, it's hard to intuitively understand why $draw() matches all
of these calls.
* As a result we've defined the term 'action' to cover these types of
events in the same way that we defined 'event' in the first place to
mean a single atomic API call.
* Moving away from 'registers' explicitly being stored, we now have a single
variable array where the shader representation is responsible for allocating
it.
* In DXBC we calculate the number of each type of mutable variable (temps,
indexable temps, and outputs) and assign slots linearly.
* We also update some naming - high-level variables aren't "locals" since they
could be globals too, and debugging variables aren't "registers" but simply
the variables we use for debugging which may be more complex than float4 for
other APIs.
* The local variable matching by string name is unnecessary for this change
but will be more useful in future after further refactors where there isn't
a single list of variables to index into at the upper level.
* In particular this means that it's safe to compare a ResourceId or similar
against None. It is always not-equal but it's useful to have the comparison
work and return the expected result instead of throwing a null reference
exception.
* Previously we would convert from python to C++ arrays immediately by
copying, and vice-versa convert TO python immediately by creating a
new python list by copying.
* This however behaves rather poorly in common situations, e.g.:
> foo.bar.append(5)
Would not append 5 to foo.bar, but copy foo.bar to a temporary, append
5 to it, then destroy it leaving foo.bar untouched.
* Instead we leave the C++ array type as a pointer for as long as we can
and instead implement the python sequence API as extensions/slots that
work in-place on the original array.
baldurk