This encapsulates Node socket members behind a set of specific methods;
as such it is no longer possible to directly access Node class members
from exporters and parts of Cycles.
The methods are defined via the NODE_SOCKET_API macros in `graph/
node.h`, and are for getting or setting a specific socket's value, as
well as querying or modifying the state of its update flag.
The setters will check whether the value has changed and tag the socket
as modified appropriately. This will let us know how a Node has changed
and what to update, which is the first concrete step toward a more
granular scene update system.
Since the setters will tag the Node sockets as modified when passed
different data, this patch also removes the various modified methods
on Nodes in favor of Node::is_modified which checks the sockets'
update flags status.
Reviewed By: brecht
Maniphest Tasks: T79174
Differential Revision: https://developer.blender.org/D8544
Uniform attributes require immediate access to the shader list
in object update code, so setting the field can't be deferred
to a background task. This required adding a parameter to the
clear method of Geometry.
Ref D2057
This splits the volume related data (properties for rendering and attributes) of the Mesh node
into a new `Volume` node type.
This `Volume` node derives from the `Mesh` class since we generate a mesh for the bounds of the
volume, as such we can safely work on `Volumes` as if they were `Meshes`, e.g. for BVH creation.
However such code should still check for the geometry type of the object to be `MESH` or `VOLUME`
which may be bug prone if this is forgotten.
This is part of T79131.
Reviewed By: brecht
Maniphest Tasks: T79131
Differential Revision: https://developer.blender.org/D8538
