Geometry Nodes: support for geometry instancing

Previously, the Point Instance node in geometry nodes could only instance
existing objects or collections. The reason was that large parts of Blender
worked under the assumption that objects are the main unit of instancing.
Now we also want to instance geometry within an object, so a slightly larger
refactor was necessary.

This should not affect files that do not use the new kind of instances.

The main change is a redefinition of what "instanced data" is. Now, an
instances is a cow-object + object-data (the geometry). This can be nicely
seen in `struct DupliObject`. This allows the same object to generate
multiple geometries of different types which can be instanced individually.

A nice side effect of this refactor is that having multiple geometry components
is not a special case in the depsgraph object iterator anymore, because those
components are integrated with the `DupliObject` system.

Unfortunately, different systems that work with instances in Blender (e.g.
render engines and exporters) often work under the assumption that objects are
the main unit of instancing. So those have to be updated as well to be able to
handle the new instances. This patch updates Cycles, EEVEE and other viewport
engines. Exporters have not been updated yet. Some minimal (not master-ready)
changes to update the obj and alembic exporters can be found in P2336 and P2335.
Different file formats may want to handle these new instances in different ways.

For users, the only thing that changed is that the Point Instance node now
has a geometry mode.

This also fixes T88454.

Differential Revision: https://developer.blender.org/D11841

1 files changed, 17 insertions, 12 deletions

diff --git a/intern/cycles/blender/blender_sync.h b/intern/cycles/blender/blender_sync.h
index 44322dda6b9..76e8f23864c 100644
--- a/intern/cycles/blender/blender_sync.h
+++ b/intern/cycles/blender/blender_sync.h
@@ -23,6 +23,7 @@
 #include "RNA_types.h"
 
 #include "blender/blender_id_map.h"
+#include "blender/blender_util.h"
 #include "blender/blender_viewport.h"
 
 #include "render/scene.h"
@@ -158,18 +159,24 @@ class BlenderSync {
   bool sync_object_attributes(BL::DepsgraphObjectInstance &b_instance, Object *object);
 
   /* Volume */
-  void sync_volume(BL::Object &b_ob, Volume *volume);
+  void sync_volume(BObjectInfo &b_ob_info, Volume *volume);
 
   /* Mesh */
-  void sync_mesh(BL::Depsgraph b_depsgraph, BL::Object b_ob, Mesh *mesh);
-  void sync_mesh_motion(BL::Depsgraph b_depsgraph, BL::Object b_ob, Mesh *mesh, int motion_step);
+  void sync_mesh(BL::Depsgraph b_depsgraph, BObjectInfo &b_ob_info, Mesh *mesh);
+  void sync_mesh_motion(BL::Depsgraph b_depsgraph,
+                        BObjectInfo &b_ob_info,
+                        Mesh *mesh,
+                        int motion_step);
 
   /* Hair */
-  void sync_hair(BL::Depsgraph b_depsgraph, BL::Object b_ob, Hair *hair);
-  void sync_hair_motion(BL::Depsgraph b_depsgraph, BL::Object b_ob, Hair *hair, int motion_step);
-  void sync_hair(Hair *hair, BL::Object &b_ob, bool motion, int motion_step = 0);
+  void sync_hair(BL::Depsgraph b_depsgraph, BObjectInfo &b_ob_info, Hair *hair);
+  void sync_hair_motion(BL::Depsgraph b_depsgraph,
+                        BObjectInfo &b_ob_info,
+                        Hair *hair,
+                        int motion_step);
+  void sync_hair(Hair *hair, BObjectInfo &b_ob_info, bool motion, int motion_step = 0);
   void sync_particle_hair(
-      Hair *hair, BL::Mesh &b_mesh, BL::Object &b_ob, bool motion, int motion_step = 0);
+      Hair *hair, BL::Mesh &b_mesh, BObjectInfo &b_ob_info, bool motion, int motion_step = 0);
   bool object_has_particle_hair(BL::Object b_ob);
 
   /* Camera */
@@ -178,14 +185,13 @@ class BlenderSync {
 
   /* Geometry */
   Geometry *sync_geometry(BL::Depsgraph &b_depsgrpah,
-                          BL::Object &b_ob,
-                          BL::Object &b_ob_instance,
+                          BObjectInfo &b_ob_info,
                           bool object_updated,
                           bool use_particle_hair,
                           TaskPool *task_pool);
 
   void sync_geometry_motion(BL::Depsgraph &b_depsgraph,
-                            BL::Object &b_ob,
+                            BObjectInfo &b_ob_info,
                             Object *object,
                             float motion_time,
                             bool use_particle_hair,
@@ -194,8 +200,7 @@ class BlenderSync {
   /* Light */
   void sync_light(BL::Object &b_parent,
                   int persistent_id[OBJECT_PERSISTENT_ID_SIZE],
-                  BL::Object &b_ob,
-                  BL::Object &b_ob_instance,
+                  BObjectInfo &b_ob_info,
                   int random_id,
                   Transform &tfm,
                   bool *use_portal);