Geometry Nodes: initial scattering and geometry nodes

This is the initial merge from the geometry-nodes branch.
Nodes:
* Attribute Math
* Boolean
* Edge Split
* Float Compare
* Object Info
* Point Distribute
* Point Instance
* Random Attribute
* Random Float
* Subdivision Surface
* Transform
* Triangulate

It includes the initial evaluation of geometry node groups in the Geometry Nodes modifier.

Notes on the Generic attribute access API

The API adds an indirection for attribute access. That has the following benefits:
* Most code does not have to care about how an attribute is stored internally.
  This is mainly necessary, because we have to deal with "legacy" attributes
  such as vertex weights and attributes that are embedded into other structs
  such as vertex positions.
* When reading from an attribute, we generally don't care what domain the
  attribute is stored on. So we want to abstract away the interpolation that
  that adapts attributes from one domain to another domain (this is not
  actually implemented yet).

Other possible improvements for later iterations include:
* Actually implement interpolation between domains.
* Don't use inheritance for the different attribute types. A single class for read
  access and one for write access might be enough, because we know all the ways
  in which attributes are stored internally. We don't want more different internal
  structures in the future. On the contrary, ideally we can consolidate the different
  storage formats in the future to reduce the need for this indirection.
* Remove the need for heap allocations when creating attribute accessors.

It includes commits from:
* Dalai Felinto
* Hans Goudey
* Jacques Lucke
* Léo Depoix

3 files changed, 16 insertions, 0 deletions

diff --git a/source/blender/depsgraph/CMakeLists.txt b/source/blender/depsgraph/CMakeLists.txt
index 2f613a0d416..95ae587f4ce 100644
--- a/source/blender/depsgraph/CMakeLists.txt
+++ b/source/blender/depsgraph/CMakeLists.txt
@@ -24,6 +24,7 @@ set(INC
   ../blenlib
   ../bmesh
   ../draw
+  ../functions
   ../makesdna
   ../makesrna
   ../modifiers
diff --git a/source/blender/depsgraph/DEG_depsgraph_build.h b/source/blender/depsgraph/DEG_depsgraph_build.h
index 2147a584765..f894bdabba4 100644
--- a/source/blender/depsgraph/DEG_depsgraph_build.h
+++ b/source/blender/depsgraph/DEG_depsgraph_build.h
@@ -141,6 +141,9 @@ void DEG_add_object_relation(struct DepsNodeHandle *node_handle,
 void DEG_add_simulation_relation(struct DepsNodeHandle *node_handle,
                                  struct Simulation *simulation,
                                  const char *description);
+void DEG_add_node_tree_relation(struct DepsNodeHandle *node_handle,
+                                struct bNodeTree *node_tree,
+                                const char *description);
 void DEG_add_bone_relation(struct DepsNodeHandle *handle,
                            struct Object *object,
                            const char *bone_name,
diff --git a/source/blender/depsgraph/intern/depsgraph_build.cc b/source/blender/depsgraph/intern/depsgraph_build.cc
index 96c17ae4dc5..6717ba521f6 100644
--- a/source/blender/depsgraph/intern/depsgraph_build.cc
+++ b/source/blender/depsgraph/intern/depsgraph_build.cc
@@ -32,6 +32,7 @@
 #include "PIL_time_utildefines.h"
 
 #include "DNA_cachefile_types.h"
+#include "DNA_node_types.h"
 #include "DNA_object_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_simulation_types.h"
@@ -116,6 +117,17 @@ void DEG_add_simulation_relation(DepsNodeHandle *node_handle,
   deg_node_handle->builder->add_node_handle_relation(operation_key, deg_node_handle, description);
 }
 
+void DEG_add_node_tree_relation(DepsNodeHandle *node_handle,
+                                bNodeTree *node_tree,
+                                const char *description)
+{
+  /* Using shading key, because that's the one that exists right now. Should use something else in
+   * the future. */
+  deg::ComponentKey shading_key(&node_tree->id, deg::NodeType::SHADING);
+  deg::DepsNodeHandle *deg_node_handle = get_node_handle(node_handle);
+  deg_node_handle->builder->add_node_handle_relation(shading_key, deg_node_handle, description);
+}
+
 void DEG_add_object_cache_relation(DepsNodeHandle *node_handle,
                                    CacheFile *cache_file,
                                    eDepsObjectComponentType component,