Files
test/source/blender/depsgraph/intern/depsgraph.hh
Jacques Lucke 2d2b087fcf Geometry Nodes: support baking data block references
With this patch, materials are kept intact in simulation zones and bake nodes
without any additional user action.

This implements the design proposed in #108410 to support referencing
data-blocks (only materials for now) in the baked data. The task also describes
why this is not a trivial issue. A previous attempt was implemented in #109703
but it didn't work well-enough.

The solution is to have an explicit `name (+ library name) -> data-block`
mapping that is stored in the modifier for each bake node and simulation zone.
The `library name` is necessary for it to be unique within a .blend file. Note
that this refers to the name of the `Library` data-block and not a file path.
The baked data only contains the names of the used data-blocks. When the baked
data is loaded, the correct material data-block is looked up from the mapping.

### Automatic Mapping Generation

The most tricky aspect of this approach is to make it feel mostly automatic.
From the user point-of-view, it should just work. Therefore, we don't want the
user to have to create the mapping manually in the majority of cases. Creating
the mapping automatically is difficult because the data-blocks that should
become part of the mapping are only known during depsgraph evaluation. So we
somehow have to gather the missing data blocks during evaluation and then write
the new mappings back to the original data.

While writing back to original data is something we do in some cases already,
the situation here is different, because we are actually creating new relations
between data-blocks. This also means that we'll have to do user-counting. Since
user counts in data-blocks are *not* atomic, we can't do that from multiple
threads at the same time. Also, under some circumstances, it may be necessary to
trigger depsgraph evaluation again after the write-back because it actually
affects the result.

To solve this, a small new API is added in `DEG_depsgraph_writeback_sync.hh`. It
allows gathering tasks which write back to original data in a synchronous way
which may also require a reevaluation.

### Accessing the Mapping

A new `BakeDataBlockMap` is passed to geometry nodes evaluation by the modifier.
This map allows getting the `ID` pointer that should be used for a specific
data-block name that is stored in baked data. It's also used to gather all the
missing data mappings during evaluation.

### Weak ID References

The baked/cached geometries may have references to other data-blocks (currently
only materials, but in the future also e.g. instanced objects/collections).
However, the pointers of these data-blocks are not stable over time. That is
especially true when storing/loading the data from disk, but also just when
playing back the animation. Therefore, the used data-blocks have to referenced
in a different way at run-time.

This is solved by adding `std::unique_ptr<bake::BakeMaterialsList>` to the
run-time data of various geometry data-blocks. If the data-block is cached over
a longer period of time (such that material pointers can't be used directly), it
stores the material name (+ library name) used by each material slot. When the
geometry is used again, the material pointers are restored using these weak name
references and the `BakeDataBlockMap`.

### Manual Mapping Management

There is a new `Data-Blocks` panel in the bake settings in the node editor
sidebar that allows inspecting and modifying the data-blocks that are used when
baking. The user can change what data-block a specific name is mapped to.

Pull Request: https://projects.blender.org/blender/blender/pulls/117043
2024-02-01 09:21:55 +01:00

191 lines
5.9 KiB
C++

/* SPDX-FileCopyrightText: 2013 Blender Authors
*
* SPDX-License-Identifier: GPL-2.0-or-later */
/** \file
* \ingroup depsgraph
*
* Datatypes for internal use in the Depsgraph
*
* All of these datatypes are only really used within the "core" depsgraph.
* In particular, node types declared here form the structure of operations
* in the graph.
*/
#pragma once
#include <functional>
#include <mutex>
#include <stdlib.h>
#include "MEM_guardedalloc.h"
#include "DNA_ID.h" /* for ID_Type and INDEX_ID_MAX */
#include "BLI_threads.h" /* for SpinLock */
#include "DEG_depsgraph.hh"
#include "DEG_depsgraph_physics.hh"
#include "intern/debug/deg_debug.h"
#include "intern/depsgraph_light_linking.hh"
#include "intern/depsgraph_type.hh"
struct ID;
struct Scene;
struct ViewLayer;
namespace blender::deg {
struct IDNode;
struct Node;
struct OperationNode;
struct Relation;
struct TimeSourceNode;
/* Dependency Graph object */
struct Depsgraph {
using OperationNodes = Vector<OperationNode *>;
using IDDepsNodes = Vector<IDNode *>;
Depsgraph(Main *bmain, Scene *scene, ViewLayer *view_layer, eEvaluationMode mode);
~Depsgraph();
TimeSourceNode *add_time_source();
TimeSourceNode *find_time_source() const;
void tag_time_source();
IDNode *find_id_node(const ID *id) const;
IDNode *add_id_node(ID *id, ID *id_cow_hint = nullptr);
void clear_id_nodes();
/** Add new relationship between two nodes. */
Relation *add_new_relation(Node *from, Node *to, const char *description, int flags = 0);
/* Check whether two nodes are connected by relation with given
* description. Description might be nullptr to check ANY relation between
* given nodes. */
Relation *check_nodes_connected(const Node *from, const Node *to, const char *description);
/* Tag a specific node as needing updates. */
void add_entry_tag(OperationNode *node);
/* Clear storage used by all nodes. */
void clear_all_nodes();
/* Copy-on-Write Functionality ........ */
/* For given original ID get ID which is created by CoW system. */
ID *get_cow_id(const ID *id_orig) const;
/* Core Graph Functionality ........... */
/* <ID : IDNode> mapping from ID blocks to nodes representing these
* blocks, used for quick lookups. */
Map<const ID *, IDNode *> id_hash;
/* Ordered list of ID nodes, order matches ID allocation order.
* Used for faster iteration, especially for areas which are critical to
* keep exact order of iteration. */
IDDepsNodes id_nodes;
/* Top-level time source node. */
TimeSourceNode *time_source;
/* The graph contains data-blocks whose visibility depends on evaluation (driven or animated). */
bool has_animated_visibility;
/* Indicates whether relations needs to be updated. */
bool need_update_relations;
/* Indicates whether indirect effect of nodes on a directly visible ones needs to be updated. */
bool need_update_nodes_visibility;
/* Indicated whether IDs in this graph are to be tagged as if they first appear visible, with
* an optional tag for their animation (time) update. */
bool need_tag_id_on_graph_visibility_update;
bool need_tag_id_on_graph_visibility_time_update;
/* Indicates which ID types were updated. */
char id_type_updated[INDEX_ID_MAX];
/* Indicates type of IDs present in the depsgraph. */
char id_type_exist[INDEX_ID_MAX];
/* Quick-Access Temp Data ............. */
/* Nodes which have been tagged as "directly modified". */
Set<OperationNode *> entry_tags;
/* Convenience Data ................... */
/* XXX: should be collected after building (if actually needed?) */
/* All operation nodes, sorted in order of single-thread traversal order. */
OperationNodes operations;
/* Spin lock for threading-critical operations.
* Mainly used by graph evaluation. */
SpinLock lock;
/* Main, scene, layer, mode this dependency graph is built for. */
Main *bmain;
Scene *scene;
ViewLayer *view_layer;
eEvaluationMode mode;
/* Time at which dependency graph is being or was last evaluated.
* frame is the value before, and ctime the value after time remapping. */
float frame;
float ctime;
/* Evaluated version of datablocks we access a lot.
* Stored here to save us form doing hash lookup. */
Scene *scene_cow;
/* Active dependency graph is a dependency graph which is used by the
* currently active window. When dependency graph is active, it is allowed
* for evaluation functions to write animation f-curve result, drivers
* result and other selective things (object matrix?) to original object.
*
* This way we simplify operators, which don't need to worry about where
* to read stuff from. */
bool is_active;
/* Optimize out evaluation of operations which affect hidden objects or disabled modifiers. */
bool use_visibility_optimization;
DepsgraphDebug debug;
bool is_evaluating;
/* Is set to truth for dependency graph which are used for post-processing (compositor and
* sequencer).
* Such dependency graph needs all view layers (so render pipeline can access names), but it
* does not need any bases. */
bool is_render_pipeline_depsgraph;
/* Notify editors about changes to IDs in this depsgraph. */
bool use_editors_update;
/* Cached list of colliders/effectors for collections and the scene
* created along with relations, for fast lookup during evaluation. */
Map<const ID *, ListBase *> *physics_relations[DEG_PHYSICS_RELATIONS_NUM];
light_linking::Cache light_linking_cache;
/* The number of times this graph has been evaluated. */
uint64_t update_count;
/**
* Stores functions that can be called after depsgraph evaluation to writeback some changes to
* original data. Also see `DEG_depsgraph_writeback_sync.hh`.
*/
Vector<std::function<void()>> sync_writeback_callbacks;
/** Needs to be locked when adding a writeback callback during evaluation. */
std::mutex sync_writeback_callbacks_mutex;
MEM_CXX_CLASS_ALLOC_FUNCS("Depsgraph");
};
} // namespace blender::deg