Simulations: Embed simulation node tree in simulation data block

This adds an embedded node tree to the simulation data block dna.
The UI in the `Simulation Editor` has been updated to show a list
of simulation data blocks, instead of individual node trees.

The new `SpaceNodeEditor.simulation` property wraps the existing
`SpaceNodeEditor.id` property. It allows scripts to get and set
the simulation data block that is being edited.

Reviewers: brecht, mont29

Differential Revision: https://developer.blender.org/D7301

3 files changed, 51 insertions, 6 deletions

diff --git a/source/blender/blenkernel/intern/lib_query.c b/source/blender/blenkernel/intern/lib_query.c
index 302ed065e5d..17d26e777b6 100644
--- a/source/blender/blenkernel/intern/lib_query.c
+++ b/source/blender/blenkernel/intern/lib_query.c
@@ -1286,6 +1286,15 @@ static void library_foreach_ID_link(Main *bmain,
         }
         break;
       }
+      case ID_SIM: {
+        Simulation *simulation = (Simulation *)id;
+        if (simulation->nodetree) {
+          /* nodetree **are owned by IDs**, treat them as mere sub-data and not real ID! */
+          library_foreach_ID_as_subdata_link(
+              (ID **)&simulation->nodetree, callback, user_data, flag, &data);
+        }
+        break;
+      }
 
       /* Nothing needed for those... */
       case ID_IM:
@@ -1295,7 +1304,6 @@ static void library_foreach_ID_link(Main *bmain,
       case ID_PAL:
       case ID_PC:
       case ID_CF:
-      case ID_SIM:
         break;
 
       /* Deprecated. */
diff --git a/source/blender/blenkernel/intern/node.c b/source/blender/blenkernel/intern/node.c
index 3f1de388db6..ec12cd9b83f 100644
--- a/source/blender/blenkernel/intern/node.c
+++ b/source/blender/blenkernel/intern/node.c
@@ -37,6 +37,7 @@
 #include "DNA_material_types.h"
 #include "DNA_node_types.h"
 #include "DNA_scene_types.h"
+#include "DNA_simulation_types.h"
 #include "DNA_texture_types.h"
 #include "DNA_world_types.h"
 
@@ -2267,6 +2268,8 @@ bNodeTree **BKE_ntree_ptr_from_id(ID *id)
       return &((Scene *)id)->nodetree;
     case ID_LS:
       return &((FreestyleLineStyle *)id)->nodetree;
+    case ID_SIM:
+      return &((Simulation *)id)->nodetree;
     default:
       return NULL;
   }
@@ -4200,6 +4203,7 @@ void BKE_node_tree_iter_init(struct NodeTreeIterStore *ntreeiter, struct Main *b
   ntreeiter->light = bmain->lights.first;
   ntreeiter->world = bmain->worlds.first;
   ntreeiter->linestyle = bmain->linestyles.first;
+  ntreeiter->simulation = bmain->simulations.first;
 }
 bool BKE_node_tree_iter_step(struct NodeTreeIterStore *ntreeiter,
                              bNodeTree **r_nodetree,
@@ -4240,6 +4244,11 @@ bool BKE_node_tree_iter_step(struct NodeTreeIterStore *ntreeiter,
     *r_id = (ID *)ntreeiter->linestyle;
     ntreeiter->linestyle = ntreeiter->linestyle->id.next;
   }
+  else if (ntreeiter->simulation) {
+    *r_nodetree = ntreeiter->simulation->nodetree;
+    *r_id = (ID *)ntreeiter->simulation;
+    ntreeiter->simulation = ntreeiter->simulation->id.next;
+  }
   else {
     return false;
   }
diff --git a/source/blender/blenkernel/intern/simulation.cc b/source/blender/blenkernel/intern/simulation.cc
index a751e376f0f..fd0bbe7103f 100644
--- a/source/blender/blenkernel/intern/simulation.cc
+++ b/source/blender/blenkernel/intern/simulation.cc
@@ -37,8 +37,11 @@
 #include "BKE_lib_query.h"
 #include "BKE_lib_remap.h"
 #include "BKE_main.h"
+#include "BKE_node.h"
 #include "BKE_simulation.h"
 
+#include "NOD_simulation.h"
+
 #include "BLT_translation.h"
 
 static void simulation_init_data(ID *id)
@@ -47,13 +50,38 @@ static void simulation_init_data(ID *id)
   BLI_assert(MEMCMP_STRUCT_AFTER_IS_ZERO(simulation, id));
 
   MEMCPY_STRUCT_AFTER(simulation, DNA_struct_default_get(Simulation), id);
+
+  bNodeTree *ntree = ntreeAddTree(nullptr, "Simulation Nodetree", ntreeType_Simulation->idname);
+  simulation->nodetree = ntree;
+}
+
+static void simulation_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const int flag)
+{
+  Simulation *simulation_dst = (Simulation *)id_dst;
+  Simulation *simulation_src = (Simulation *)id_src;
+
+  /* We always need allocation of our private ID data. */
+  const int flag_private_id_data = flag & ~LIB_ID_CREATE_NO_ALLOCATE;
+
+  if (simulation_src->nodetree) {
+    BKE_id_copy_ex(bmain,
+                   (ID *)simulation_src->nodetree,
+                   (ID **)&simulation_dst->nodetree,
+                   flag_private_id_data);
+  }
 }
 
-static void simulation_copy_data(Main *UNUSED(bmain),
-                                 ID *UNUSED(id_dst),
-                                 const ID *UNUSED(id_src),
-                                 const int UNUSED(flag))
+static void simulation_free_data(ID *id)
 {
+  Simulation *simulation = (Simulation *)id;
+
+  BKE_animdata_free(&simulation->id, false);
+
+  if (simulation->nodetree) {
+    ntreeFreeNestedTree(simulation->nodetree);
+    MEM_freeN(simulation->nodetree);
+    simulation->nodetree = nullptr;
+  }
 }
 
 void *BKE_simulation_add(Main *bmain, const char *name)
@@ -77,6 +105,6 @@ IDTypeInfo IDType_ID_SIM = {
 
     /* init_data */ simulation_init_data,
     /* copy_data */ simulation_copy_data,
-    /* free_data */ nullptr,
+    /* free_data */ simulation_free_data,
     /* make_local */ nullptr,
 };