Depsgraph: cache effector relations, for performance and stability.

To find all effectors in the scene, we need to loop over all objects.
Doing this during depsgraph evaluation caused crashes because not all
objects are guaranteed to be evaluated yet.

To fix this, we now cache the relations as part of the dependency graph
build. As a bonus this also makes evaluation faster for big scenes,
since looping over all objects for each particle system is slow.

Fixes T55156.

1 files changed, 94 insertions, 0 deletions

diff --git a/source/blender/depsgraph/intern/depsgraph_physics.cc b/source/blender/depsgraph/intern/depsgraph_physics.cc
new file mode 100644
index 00000000000..d26ba845dd5
--- /dev/null
+++ b/source/blender/depsgraph/intern/depsgraph_physics.cc
@@ -0,0 +1,94 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2018 Blender Foundation.
+ * All rights reserved.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/depsgraph/intern/depsgraph_physics.cc
+ *  \ingroup depsgraph
+ *
+ * Physics utilities for effectors and collision.
+ */
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_compiler_compat.h"
+#include "BLI_ghash.h"
+
+extern "C" {
+#include "BKE_effect.h"
+} /* extern "C" */
+
+#include "DNA_group_types.h"
+
+#include "DEG_depsgraph_physics.h"
+
+#include "depsgraph.h"
+#include "depsgraph_intern.h"
+
+/************************ Public API *************************/
+
+ListBase *DEG_get_effector_relations(const Depsgraph *graph,
+                                     Collection *collection)
+{
+	const DEG::Depsgraph *deg_graph = reinterpret_cast<const DEG::Depsgraph *>(graph);
+	if (deg_graph->effector_relations == NULL) {
+		return NULL;
+	}
+
+	return (ListBase*)BLI_ghash_lookup(deg_graph->effector_relations, collection);
+}
+
+/*********************** Internal API ************************/
+
+namespace DEG
+{
+
+ListBase *deg_build_effector_relations(Depsgraph *graph,
+                                       Collection *collection)
+{
+	if (graph->effector_relations == NULL) {
+		graph->effector_relations = BLI_ghash_ptr_new("Depsgraph effector relations hash");
+	}
+
+	ListBase *relations = reinterpret_cast<ListBase*>(BLI_ghash_lookup(graph->effector_relations, collection));
+	if (relations == NULL) {
+		::Depsgraph *depsgraph = reinterpret_cast<::Depsgraph*>(graph);
+		relations = BKE_effector_relations_create(depsgraph, graph->view_layer, collection);
+		BLI_ghash_insert(graph->effector_relations, collection, relations);
+	}
+
+	return relations;
+}
+
+static void free_effector_relations(void *value)
+{
+	BKE_effector_relations_free(reinterpret_cast<ListBase*>(value));
+}
+
+void deg_clear_physics_relations(Depsgraph *graph)
+{
+	if (graph->effector_relations) {
+		BLI_ghash_free(graph->effector_relations, NULL, free_effector_relations);
+		graph->effector_relations = NULL;
+	}
+}
+
+}