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, 24 insertions, 18 deletions

diff --git a/intern/cycles/blender/blender_curves.cpp b/intern/cycles/blender/blender_curves.cpp
index 85d886fd850..6fe5ea41fff 100644
--- a/intern/cycles/blender/blender_curves.cpp
+++ b/intern/cycles/blender/blender_curves.cpp
@@ -526,8 +526,13 @@ bool BlenderSync::object_has_particle_hair(BL::Object b_ob)
 
 /* Old particle hair. */
 void BlenderSync::sync_particle_hair(
-    Hair *hair, BL::Mesh &b_mesh, BL::Object &b_ob, bool motion, int motion_step)
+    Hair *hair, BL::Mesh &b_mesh, BObjectInfo &b_ob_info, bool motion, int motion_step)
 {
+  if (!b_ob_info.is_real_object_data()) {
+    return;
+  }
+  BL::Object b_ob = b_ob_info.real_object;
+
   /* obtain general settings */
   if (b_ob.mode() == b_ob.mode_PARTICLE_EDIT || b_ob.mode() == b_ob.mode_EDIT) {
     return;
@@ -788,10 +793,10 @@ static void export_hair_curves_motion(Hair *hair, BL::Hair b_hair, int motion_st
 }
 
 /* Hair object. */
-void BlenderSync::sync_hair(Hair *hair, BL::Object &b_ob, bool motion, int motion_step)
+void BlenderSync::sync_hair(Hair *hair, BObjectInfo &b_ob_info, bool motion, int motion_step)
 {
   /* Convert Blender hair to Cycles curves. */
-  BL::Hair b_hair(b_ob.data());
+  BL::Hair b_hair(b_ob_info.object_data);
   if (motion) {
     export_hair_curves_motion(hair, b_hair, motion_step);
   }
@@ -800,16 +805,16 @@ void BlenderSync::sync_hair(Hair *hair, BL::Object &b_ob, bool motion, int motio
   }
 }
 #else
-void BlenderSync::sync_hair(Hair *hair, BL::Object &b_ob, bool motion, int motion_step)
+void BlenderSync::sync_hair(Hair *hair, BObjectInfo &b_ob_info, bool motion, int motion_step)
 {
   (void)hair;
-  (void)b_ob;
+  (void)b_ob_info;
   (void)motion;
   (void)motion_step;
 }
 #endif
 
-void BlenderSync::sync_hair(BL::Depsgraph b_depsgraph, BL::Object b_ob, Hair *hair)
+void BlenderSync::sync_hair(BL::Depsgraph b_depsgraph, BObjectInfo &b_ob_info, Hair *hair)
 {
   /* make a copy of the shaders as the caller in the main thread still need them for syncing the
    * attributes */
@@ -819,19 +824,19 @@ void BlenderSync::sync_hair(BL::Depsgraph b_depsgraph, BL::Object b_ob, Hair *ha
   new_hair.set_used_shaders(used_shaders);
 
   if (view_layer.use_hair) {
-    if (b_ob.type() == BL::Object::type_HAIR) {
+    if (b_ob_info.object_data.is_a(&RNA_Hair)) {
       /* Hair object. */
-      sync_hair(&new_hair, b_ob, false);
+      sync_hair(&new_hair, b_ob_info, false);
     }
     else {
       /* Particle hair. */
       bool need_undeformed = new_hair.need_attribute(scene, ATTR_STD_GENERATED);
       BL::Mesh b_mesh = object_to_mesh(
-          b_data, b_ob, b_depsgraph, need_undeformed, Mesh::SUBDIVISION_NONE);
+          b_data, b_ob_info, b_depsgraph, need_undeformed, Mesh::SUBDIVISION_NONE);
 
       if (b_mesh) {
-        sync_particle_hair(&new_hair, b_mesh, b_ob, false);
-        free_object_to_mesh(b_data, b_ob, b_mesh);
+        sync_particle_hair(&new_hair, b_mesh, b_ob_info, false);
+        free_object_to_mesh(b_data, b_ob_info, b_mesh);
       }
     }
   }
@@ -859,7 +864,7 @@ void BlenderSync::sync_hair(BL::Depsgraph b_depsgraph, BL::Object b_ob, Hair *ha
 }
 
 void BlenderSync::sync_hair_motion(BL::Depsgraph b_depsgraph,
-                                   BL::Object b_ob,
+                                   BObjectInfo &b_ob_info,
                                    Hair *hair,
                                    int motion_step)
 {
@@ -869,18 +874,19 @@ void BlenderSync::sync_hair_motion(BL::Depsgraph b_depsgraph,
   }
 
   /* Export deformed coordinates. */
-  if (ccl::BKE_object_is_deform_modified(b_ob, b_scene, preview)) {
-    if (b_ob.type() == BL::Object::type_HAIR) {
+  if (ccl::BKE_object_is_deform_modified(b_ob_info, b_scene, preview)) {
+    if (b_ob_info.object_data.is_a(&RNA_Hair)) {
       /* Hair object. */
-      sync_hair(hair, b_ob, true, motion_step);
+      sync_hair(hair, b_ob_info, true, motion_step);
       return;
     }
     else {
       /* Particle hair. */
-      BL::Mesh b_mesh = object_to_mesh(b_data, b_ob, b_depsgraph, false, Mesh::SUBDIVISION_NONE);
+      BL::Mesh b_mesh = object_to_mesh(
+          b_data, b_ob_info, b_depsgraph, false, Mesh::SUBDIVISION_NONE);
       if (b_mesh) {
-        sync_particle_hair(hair, b_mesh, b_ob, true, motion_step);
-        free_object_to_mesh(b_data, b_ob, b_mesh);
+        sync_particle_hair(hair, b_mesh, b_ob_info, true, motion_step);
+        free_object_to_mesh(b_data, b_ob_info, b_mesh);
         return;
       }
     }