Depsgraph: New dependency graph integration commit

This commit integrates the work done so far on the new dependency graph system,
where goal was to replace legacy depsgraph with the new one, supporting loads of
neat features like:

- More granular dependency relation nature, which solves issues with fake cycles
  in the dependencies.

- Move towards all-animatable, by better integration of drivers into the system.

- Lay down some basis for upcoming copy-on-write, overrides and so on.

The new system is living side-by-side with the previous one and disabled by
default, so nothing will become suddenly broken. The way to enable new depsgraph
is to pass `--new-depsgraph` command line argument.

It's a bit early to consider the system production-ready, there are some TODOs
and issues were discovered during the merge period, they'll be addressed ASAP.
But it's important to merge, because it's the only way to attract artists to
really start testing this system.

There are number of assorted documents related on the design of the new system:

* http://wiki.blender.org/index.php/User:Aligorith/GSoC2013_Depsgraph#Design_Documents
* http://wiki.blender.org/index.php/User:Nazg-gul/DependencyGraph

There are also some user-related information online:

* http://code.blender.org/2015/02/blender-dependency-graph-branch-for-users/
* http://code.blender.org/2015/03/more-dependency-graph-tricks/

Kudos to everyone who was involved into the project:

- Joshua "Aligorith" Leung -- design specification, initial code
- Lukas "lukas_t" Toenne -- integrating code into blender, with further fixes
- Sergey "Sergey" "Sharybin" -- some mocking around, trying to wrap up the
  project and so
- Bassam "slikdigit" Kurdali -- stressing the new system, reporting all the
  issues and recording/writing documentation.
- Everyone else who i forgot to mention here :)

1 files changed, 210 insertions, 0 deletions

diff --git a/source/blender/depsgraph/DEG_depsgraph.h b/source/blender/depsgraph/DEG_depsgraph.h
new file mode 100644
index 00000000000..9fc50476e47
--- /dev/null
+++ b/source/blender/depsgraph/DEG_depsgraph.h
@@ -0,0 +1,210 @@
+/*
+ * ***** 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) 2013 Blender Foundation.
+ * All rights reserved.
+ *
+ * Original Author: Joshua Leung
+ * Contributor(s): None Yet
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ *
+ * Public API for Depsgraph
+ */
+
+#ifndef __DEG_DEPSGRAPH_H__
+#define __DEG_DEPSGRAPH_H__
+
+/* Dependency Graph
+ *
+ * The dependency graph tracks relations between various pieces of data in
+ * a Blender file, but mainly just those which make up scene data. It is used
+ * to determine the set of operations need to ensure that all data has been
+ * correctly evaluated in response to changes, based on dependencies and visibility
+ * of affected data.
+ *
+ *
+ * Evaluation Engine
+ *
+ * The evaluation takes the operation-nodes the Depsgraph has tagged for updating, 
+ * and schedules them up for being evaluated/executed such that the all dependency
+ * relationship constraints are satisfied. 
+ */
+
+/* ************************************************* */
+/* Forward-defined typedefs for core types
+ * - These are used in all depsgraph code and by all callers of Depsgraph API...
+ */
+
+/* Dependency Graph */
+typedef struct Depsgraph Depsgraph;
+
+/* ------------------------------------------------ */
+
+struct EvaluationContext;
+struct Main;
+
+struct PointerRNA;
+struct PropertyRNA;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+bool DEG_depsgraph_use_legacy(void);
+void DEG_depsgraph_switch_to_legacy(void);
+void DEG_depsgraph_switch_to_new(void);
+
+/* ************************************************ */
+/* Depsgraph API */
+
+/* CRUD ------------------------------------------- */
+
+// Get main depsgraph instance from context!
+
+/* Create new Depsgraph instance */
+// TODO: what args are needed here? What's the building-graph entry point?
+Depsgraph *DEG_graph_new(void);
+
+/* Free Depsgraph itself and all its data */
+void DEG_graph_free(Depsgraph *graph);
+
+/* Node Types Registry ---------------------------- */
+
+/* Register all node types */
+void DEG_register_node_types(void);
+
+/* Free node type registry on exit */
+void DEG_free_node_types(void);
+
+/* Update Tagging -------------------------------- */
+
+/* Tag node(s) associated with states such as time and visibility */
+void DEG_scene_update_flags(Depsgraph *graph, const bool do_time);
+
+/* Update dependency graph when visible scenes/layers changes. */
+void DEG_graph_on_visible_update(struct Main *bmain, struct Scene *scene);
+
+/* Update all dependency graphs when visible scenes/layers changes. */
+void DEG_on_visible_update(struct Main *bmain, const bool do_time);
+
+/* Tag node(s) associated with changed data for later updates */
+void DEG_graph_id_tag_update(struct Main *bmain,
+                             Depsgraph *graph,
+                             struct ID *id);
+void DEG_graph_data_tag_update(Depsgraph *graph, const struct PointerRNA *ptr);
+void DEG_graph_property_tag_update(Depsgraph *graph, const struct PointerRNA *ptr, const struct PropertyRNA *prop);
+
+/* Tag given ID for an update in all the dependency graphs. */
+void DEG_id_tag_update(struct ID *id, short flag);
+void DEG_id_tag_update_ex(struct Main *bmain,
+                          struct ID *id,
+                          short flag);
+
+/* Tag given ID type for update.
+ *
+ * Used by all sort of render engines to quickly check if
+ * IDs of a given type need to be checked for update.
+ */
+void DEG_id_type_tag(struct Main *bmain, short idtype);
+
+void DEG_ids_clear_recalc(struct Main *bmain);
+
+/* Update Flushing ------------------------------- */
+
+/* Flush updates */
+void DEG_graph_flush_updates(struct Main *bmain, Depsgraph *graph);
+
+/* Flush updates for all IDs */
+void DEG_ids_flush_tagged(struct Main *bmain);
+
+/* Check if something was changed in the database and inform
+ * editors about this.
+ */
+void DEG_ids_check_recalc(struct Main *bmain,
+                          struct Scene *scene,
+                          bool time);
+
+/* Clear all update tags
+ * - For aborted updates, or after successful evaluation
+ */
+void DEG_graph_clear_tags(Depsgraph *graph);
+
+/* ************************************************ */
+/* Evaluation Engine API */
+
+/* Evaluation Context ---------------------------- */
+
+/* Create new evaluation context. */
+struct EvaluationContext *DEG_evaluation_context_new(int mode);
+
+/* Initialize evaluation context.
+ * Used by the areas which currently overrides the context or doesn't have
+ * access to a proper one.
+ */
+void DEG_evaluation_context_init(struct EvaluationContext *eval_ctx, int mode);
+
+/* Free evaluation context. */
+void DEG_evaluation_context_free(struct EvaluationContext *eval_ctx);
+
+/* Graph Evaluation  ----------------------------- */
+
+/* Frame changed recalculation entry point
+ * < context_type: context to perform evaluation for
+ * < ctime: (frame) new frame to evaluate values on
+ */
+void DEG_evaluate_on_framechange(struct EvaluationContext *eval_ctx,
+                                 struct Main *bmain,
+                                 Depsgraph *graph,
+                                 float ctime,
+                                 const int layer);
+
+/* Data changed recalculation entry point.
+ * < context_type: context to perform evaluation for
+ * < layers: visible layers bitmask to update the graph for
+ */
+void DEG_evaluate_on_refresh_ex(struct EvaluationContext *eval_ctx,
+                                Depsgraph *graph,
+                                const int layers);
+
+/* Data changed recalculation entry point.
+ * < context_type: context to perform evaluation for
+ */
+void DEG_evaluate_on_refresh(struct EvaluationContext *eval_ctx,
+                             Depsgraph *graph,
+                             struct Scene *scene);
+
+/* Editors Integration  -------------------------- */
+
+/* Mechanism to allow editors to be informed of depsgraph updates,
+ * to do their own updates based on changes.
+ */
+
+typedef void (*DEG_EditorUpdateIDCb)(struct Main *bmain, struct ID *id);
+typedef void (*DEG_EditorUpdateSceneCb)(struct Main *bmain,
+                                        struct Scene *scene,
+                                        int updated);
+
+/* Set callbacks which are being called when depsgraph changes. */
+void DEG_editors_set_update_cb(DEG_EditorUpdateIDCb id_func,
+                               DEG_EditorUpdateSceneCb scene_func);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif  /* __DEG_DEPSGRAPH_H__ */