Blender Git Loki

Geometry Nodes : Removing "Combine Strings" and Group Instance ID from UI

This diff remove "Combine Strings" and "Group Instance ID" nodes from the UI (but keep them in the source code to be able to bring them back if needed).

This is part of "Cleanup 1st Sprint Nodes" (https://developer.blender.org/T82370).

Differential Revision: https://developer.blender.org/D9558

Rename: "Nodes" modifier to "Empty"

This introduces a regression. Users need to re-create their modifiers
and set their values again. The NodeGroups are intact so all they need
is to create new "Empty" modifiers and set the node group.

---

Original problem: Eventually most modifiers will be node-based, so naming
this new modifier "Nodes" will get outdated pretty quickly.

Calling it "Empty" it's fairly descriptive, since the node tree simply connects
the modifier Input to an Output, without any effect.

There is a potential problem, that it could be associated with the
Empty object type. Like some sort of Hook.

This is the task T82700, and the design task T82537.

Geometry Nodes: Improve error messages for property mismatches

Related to T82438. This adds some basic checks for common errors and
currently unsupported socket types in the modifier.

Merge branch 'master' into geometry-nodes

Cleanup: Remove unused variable

Cleanup: Clang Tidy

Cleanup: Spelling

Also move some input extraction after the special case check.

Geometry Nodes: Add method enums to mesh triangulate node

This commit adds the remaining "method" enums from the triangulate modifier.

Differential Revision: https://developer.blender.org/D9502

Merge branch 'master' into geometry-nodes

Geometry Nodes: Add null check for modifier property UI functions

An ID IDProperty exposed to the modifier (object, material, etc) does not
have min, max, etc. values, so they should not be required.

Cleanup: Fix typo

Geometry Nodes: Add modifier disabled check

Geometry Nodes: use density attribute name instead of index as node input

This implements a workaround for the issue that (for historical reasons)
the names of vertex groups are stored on the object while the actual vertex
group data is stored on the mesh.

The solution is to copy the vertex group names from the object into
the `MeshComponent` so that the information is not lost, when the
object cannot be accessed.

Geometry Nodes: cleanup geometry node interface

Previously, the execution function of a geometry node has three parameters.
Now it has only one. This makes it easier to pass more information to the
execution function, that might only be used by a few nodes, because we
don't have to add more parameters that are unused in most cases.

Geometry Nodes: actually create instances in Point Instance node

Geometry Nodes: support instances in Transform node

Geometry Nodes: new DupliGenerator for instances component

With this, instances generated in a node tree can be rendered.

Geometry Nodes: improve point distribute node

* Support vertex weights to control density.
* O(n) performance instead of O(n^2).
* More stable when density weights are changed.

The vertex group has to be specified using an index for now.
This is a technical limitation that will resolved a bit later.

Geometry Nodes: support geometry components in depsgraph object iterator

Objects can evaluate to a geometry set instead of a single ID (only point cloud
objects for now). In the depsgraph object iterator, those geometry components
are expanded into temporary objects.

It's important to note that instanced objects can also contain geometry
components. Therefore, they have to be split up into multiple objects
as well in some cases.

At a high level the iterator works like so:
```
for object in depsgraph:
for component in object:
yield object_from_component(component)
for dupli in make_duplis_list(object):
for component in dupli:
yield object_from_component(component)
```

DEG_iterator_objects_next has been cleaned up, to make this structure
a bit more apparent.

Geometry Nodes: better handle link cycles