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

2 files changed, 63 insertions, 16 deletions

diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index 7f850435a64..9590a4aa7ee 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -632,14 +632,29 @@ void DRW_viewport_request_redraw(void)
 /** \name Duplis
  * \{ */
 
-static void drw_duplidata_load(DupliObject *dupli)
+static uint dupli_key_hash(const void *key)
 {
+  const DupliKey *dupli_key = (const DupliKey *)key;
+  return BLI_ghashutil_ptrhash(dupli_key->ob) ^ BLI_ghashutil_ptrhash(dupli_key->ob_data);
+}
+
+static bool dupli_key_cmp(const void *key1, const void *key2)
+{
+  const DupliKey *dupli_key1 = (const DupliKey *)key1;
+  const DupliKey *dupli_key2 = (const DupliKey *)key2;
+  return dupli_key1->ob != dupli_key2->ob || dupli_key1->ob_data != dupli_key2->ob_data;
+}
+
+static void drw_duplidata_load(Object *ob)
+{
+  DupliObject *dupli = DST.dupli_source;
   if (dupli == NULL) {
     return;
   }
 
-  if (DST.dupli_origin != dupli->ob) {
+  if (DST.dupli_origin != dupli->ob || (DST.dupli_origin_data != dupli->ob_data)) {
     DST.dupli_origin = dupli->ob;
+    DST.dupli_origin_data = dupli->ob_data;
   }
   else {
     /* Same data as previous iter. No need to poll ghash for this. */
@@ -647,16 +662,23 @@ static void drw_duplidata_load(DupliObject *dupli)
   }
 
   if (DST.dupli_ghash == NULL) {
-    DST.dupli_ghash = BLI_ghash_ptr_new(__func__);
+    DST.dupli_ghash = BLI_ghash_new(dupli_key_hash, dupli_key_cmp, __func__);
   }
 
+  DupliKey *key = MEM_callocN(sizeof(DupliKey), __func__);
+  key->ob = dupli->ob;
+  key->ob_data = dupli->ob_data;
+
   void **value;
-  if (!BLI_ghash_ensure_p(DST.dupli_ghash, DST.dupli_origin, &value)) {
+  if (!BLI_ghash_ensure_p(DST.dupli_ghash, key, &value)) {
     *value = MEM_callocN(sizeof(void *) * DST.enabled_engine_count, __func__);
 
     /* TODO: Meh a bit out of place but this is nice as it is
-     * only done once per "original" object. */
-    drw_batch_cache_validate(DST.dupli_origin);
+     * only done once per instance type. */
+    drw_batch_cache_validate(ob);
+  }
+  else {
+    MEM_freeN(key);
   }
   DST.dupli_datas = *(void ***)value;
 }
@@ -670,12 +692,24 @@ static void duplidata_value_free(void *val)
   MEM_freeN(val);
 }
 
+static void duplidata_key_free(void *key)
+{
+  DupliKey *dupli_key = (DupliKey *)key;
+  if (dupli_key->ob_data == NULL) {
+    drw_batch_cache_generate_requested(dupli_key->ob);
+  }
+  else {
+    Object temp_object = *dupli_key->ob;
+    BKE_object_replace_data_on_shallow_copy(&temp_object, dupli_key->ob_data);
+    drw_batch_cache_generate_requested(&temp_object);
+  }
+  MEM_freeN(key);
+}
+
 static void drw_duplidata_free(void)
 {
   if (DST.dupli_ghash != NULL) {
-    BLI_ghash_free(DST.dupli_ghash,
-                   (void (*)(void *key))drw_batch_cache_generate_requested,
-                   duplidata_value_free);
+    BLI_ghash_free(DST.dupli_ghash, duplidata_key_free, duplidata_value_free);
     DST.dupli_ghash = NULL;
   }
 }
@@ -1523,6 +1557,7 @@ void DRW_draw_render_loop_ex(struct Depsgraph *depsgraph,
     /* Only iterate over objects for internal engines or when overlays are enabled */
     if (do_populate_loop) {
       DST.dupli_origin = NULL;
+      DST.dupli_origin_data = NULL;
       DEG_OBJECT_ITER_FOR_RENDER_ENGINE_BEGIN (depsgraph, ob) {
         if ((object_type_exclude_viewport & (1 << ob->type)) != 0) {
           continue;
@@ -1532,7 +1567,7 @@ void DRW_draw_render_loop_ex(struct Depsgraph *depsgraph,
         }
         DST.dupli_parent = data_.dupli_parent;
         DST.dupli_source = data_.dupli_object_current;
-        drw_duplidata_load(DST.dupli_source);
+        drw_duplidata_load(ob);
         drw_engines_cache_populate(ob);
       }
       DEG_OBJECT_ITER_FOR_RENDER_ENGINE_END;
@@ -1881,12 +1916,13 @@ void DRW_render_object_iter(
                                                draw_ctx->v3d->object_type_exclude_viewport :
                                                0;
   DST.dupli_origin = NULL;
+  DST.dupli_origin_data = NULL;
   DEG_OBJECT_ITER_FOR_RENDER_ENGINE_BEGIN (depsgraph, ob) {
     if ((object_type_exclude_viewport & (1 << ob->type)) == 0) {
       DST.dupli_parent = data_.dupli_parent;
       DST.dupli_source = data_.dupli_object_current;
       DST.ob_handle = 0;
-      drw_duplidata_load(DST.dupli_source);
+      drw_duplidata_load(ob);
 
       if (!DST.dupli_source) {
         drw_batch_cache_validate(ob);
@@ -2330,6 +2366,7 @@ void DRW_draw_select_loop(struct Depsgraph *depsgraph,
                                               v3d->object_type_exclude_select);
       bool filter_exclude = false;
       DST.dupli_origin = NULL;
+      DST.dupli_origin_data = NULL;
       DEG_OBJECT_ITER_FOR_RENDER_ENGINE_BEGIN (depsgraph, ob) {
         if (!BKE_object_is_visible_in_viewport(v3d, ob)) {
           continue;
@@ -2362,7 +2399,7 @@ void DRW_draw_select_loop(struct Depsgraph *depsgraph,
           DRW_select_load_id(ob->runtime.select_id);
           DST.dupli_parent = data_.dupli_parent;
           DST.dupli_source = data_.dupli_object_current;
-          drw_duplidata_load(DST.dupli_source);
+          drw_duplidata_load(ob);
           drw_engines_cache_populate(ob);
         }
       }
@@ -2475,6 +2512,7 @@ static void drw_draw_depth_loop_impl(struct Depsgraph *depsgraph,
 
     const int object_type_exclude_viewport = v3d->object_type_exclude_viewport;
     DST.dupli_origin = NULL;
+    DST.dupli_origin_data = NULL;
     DEG_OBJECT_ITER_FOR_RENDER_ENGINE_BEGIN (DST.draw_ctx.depsgraph, ob) {
       if ((object_type_exclude_viewport & (1 << ob->type)) != 0) {
         continue;
@@ -2484,7 +2522,7 @@ static void drw_draw_depth_loop_impl(struct Depsgraph *depsgraph,
       }
       DST.dupli_parent = data_.dupli_parent;
       DST.dupli_source = data_.dupli_object_current;
-      drw_duplidata_load(DST.dupli_source);
+      drw_duplidata_load(ob);
       drw_engines_cache_populate(ob);
     }
     DEG_OBJECT_ITER_FOR_RENDER_ENGINE_END;
diff --git a/source/blender/draw/intern/draw_manager.h b/source/blender/draw/intern/draw_manager.h
index 33e1a57198c..1747ca752c7 100644
--- a/source/blender/draw/intern/draw_manager.h
+++ b/source/blender/draw/intern/draw_manager.h
@@ -497,6 +497,11 @@ typedef struct DRWDebugSphere {
 
 /* ------------- DRAW MANAGER ------------ */
 
+typedef struct DupliKey {
+  struct Object *ob;
+  struct ID *ob_data;
+} DupliKey;
+
 #define DST_MAX_SLOTS 64  /* Cannot be changed without modifying RST.bound_tex_slots */
 #define MAX_CLIP_PLANES 6 /* GL_MAX_CLIP_PLANES is at least 6 */
 #define STENCIL_UNDEFINED 256
@@ -515,15 +520,19 @@ typedef struct DRWManager {
   /** Handle of next DRWPass to be allocated. */
   DRWResourceHandle pass_handle;
 
-  /** Dupli state. NULL if not dupli. */
+  /** Dupli object that corresponds to the current object. */
   struct DupliObject *dupli_source;
+  /** Object that created the dupli-list the current object is part of. */
   struct Object *dupli_parent;
+  /** Object referenced by the current dupli object. */
   struct Object *dupli_origin;
-  /** Ghash containing original objects. */
+  /** Object-data referenced by the current dupli object. */
+  struct ID *dupli_origin_data;
+  /** Ghash: #DupliKey -> void pointer for each enabled engine. */
   struct GHash *dupli_ghash;
   /** TODO(fclem): try to remove usage of this. */
   DRWInstanceData *object_instance_data[MAX_INSTANCE_DATA_SIZE];
-  /* Array of dupli_data (one for each enabled engine) to handle duplis. */
+  /* Dupli data for the current dupli for each enabled engine. */
   void **dupli_datas;
 
   /* Rendering state */