PyNodes opens up the node system in Blender to scripters and adds a number of UI-level improvements.
=== Dynamic node type registration ===
Node types can now be added at runtime, using the RNA registration mechanism from python. This enables addons such as render engines to create a complete user interface with nodes.
Examples of how such nodes can be defined can be found in my personal wiki docs atm [1] and as a script template in release/scripts/templates_py/custom_nodes.py [2].
=== Node group improvements ===
Each node editor now has a tree history of edited node groups, which allows opening and editing nested node groups. The node editor also supports pinning now, so that different spaces can be used to edit different node groups simultaneously. For more ramblings and rationale see (really old) blog post on code.blender.org [3].
The interface of node groups has been overhauled. Sockets of a node group are no longer displayed in columns on either side, but instead special input/output nodes are used to mirror group sockets inside a node tree. This solves the problem of long node lines in groups and allows more adaptable node layout. Internal sockets can be exposed from a group by either connecting to the extension sockets in input/output nodes (shown as empty circle) or by adding sockets from the node property bar in the "Interface" panel. Further details such as the socket name can also be changed there.
[1] http://wiki.blender.org/index.php/User:Phonybone/Python_Nodes
[2] http://projects.blender.org/scm/viewvc.php/trunk/blender/release/scripts/templates_py/custom_nodes.py?view=markup&root=bf-blender
[3] http://code.blender.org/index.php/2012/01/improving-node-group-interface-editing/
It is not a well-supported feature of the primary node systems (shader, compositor, texture) in Blender. If anybody wants to create a node system that has actual use for loops, they can do so much more elegantly with Python nodes, but it does not have to be a core node type in Blender. Removing this should ease node code maintenance a bit.
The reason is that the per-node updates used for Reroute node type inheritance are not supposed to be looking at connected nodes, they are purely for "local" updates. For this sort of "global" update which requires depth-first search, the update function on the node tree level must be used instead.
1) For inserting into existing groups:
The 'Make Group from selected' (CTRL+g) operator shows a selection popup (like the object parenting operator), with options depending on the type of the active node (last selected):
* "New" -> regular operator, creates new group type with all selected nodes inside.
* "Insert" (only if active node is a group) -> adds all other selected nodes into the group.
Currently still prohibits groups inside groups in general, though would be technically possible as long as no actual recursion occurs (group containing itself).
2) For extracting from an existing group:
New 'Separate from group' operator (p), works similar to separating vertices/edges/faces from mesh. Two modes:
* "Copy" makes a copy of the nodes in the parent tree, but keeps the original group intact.
* "Move" removes selected nodes from the node group and adds them to the parent tree
This branch adds mostly organizational improvements to the node system by renaming the node folders and files. A couple of internal features have been added too.
Detailed information can be found on the wiki page:
http://wiki.blender.org/index.php/User:Phonybone/Particles2010
