This was many changes that were largely fundamentally related. They included:
- More const modifiers to enforce read only node graphs
- Support for fragment and vertex shaders from the nodes
- Support for node code loaded externally (embedded into the binary)
- Fixed issue preventing two textures from being used in a shader
- Removed several unused functions and cleaned up code
- Fixed video media node misreading its matrix input
If the nodes are now stateless, there's nothing stopping the renderer from
rendering multiple frames at once. Earlier since the nodes held some of their
input/output data (and that data could change per frame), it was not possible
to render multiple frames at once without conflicts. Now that the node state is
held in render threads, they can do whatever they want at any time.
Since all Nodes have an output that provides all output values now, we now
never need to add an output from a Node derivative. These changes remove the
last of them and disable the ability to add more outputs from a derivative.
If Nodes only have the one output, we don't need to do so much differentiation
between them. Previous iteration used outputs as like a distinct function
within a Node (e.g. length output would return one result, buffer output would
produce a different result - each run different code to produce their results).
Now in this iteration, it's more accurate to say a Node is just one function
(which seems more appropriate for a node system anyway).
Since the nodes won't be holding any rendering data themselves in this system,
we may as well enforce some level of non-write access by setting all the
functions to const. They were already const-friendly, they just weren't
labelled as such.
Fixes a "pure virtual method" crash. The inputs will try to send invalidate
cache signals through the node while it's being destroyed if these are left
connected. There's no purpose to sending invalidate cache signals since any
nodes affected by this one will automatically invalidate the cache from its
outputs being disconnected and the node being destroyed so this shouldn't
cause issues.
NodeParams used to be destroyed automatically through the QObject system, but
now that NodeParams perform actions that access the parent Node object in
their destructor, the NodeParam destructor needs to be called before the Node
has been fully destroyed. By destroying explicitly in the Node destructor we
accomplish this.
Old code assumes that a NodeParam's parent will always be a Node. The function
has been separated off and tweaked in the event that this is not the case.
Since we're now working with a separate proxy copy of the original node graph,
if the user changes a parameter in one of those nodes (triggering an
InvalidateCache signal), the values in our copied graph need to be updated
with these new values too.
Useful for detecting when a graph needs recompiling, in tandem with the
"InvalidateCache()" signal when necessary, this signal ripples through the
nodes when any of the connections change which will likely need handling by
the renderer.
Sometimes we'll be copying nodes without wanting to copy their connections,
since we'll want to connect them to equivalent copies rather than connecting
them to the same nodes the originals were connected to. We now have an extra
parameter to distinguish such operations.
Once again, conceptually this system should work, however it does not seem to
be the most efficient and it wouldn't surprise me if the multithreading was
eventually upgraded to an even more coherent system one day. However for
"core principles" this should be fairly decent.
The new rendering pipeline strives to simplify the nodes themselves as much
as possible and move much of the logic to an external rendering engine. This
change removes all of the responsibilities that no longer belong to the
nodes themselves and will soon be folded into the renderer.
Nodes were previously written to be "strongly typed" in that a parameter's
"type" enforced whether it could be connected to another. All code related
to that has now been removed since not only is it hard to maintain and
likely unnecessary, it's possible the nodes will work differently later on
anyway.
itsmattkc