e955c94ed3
Listing the "Blender Foundation" as copyright holder implied the Blender Foundation holds copyright to files which may include work from many developers. While keeping copyright on headers makes sense for isolated libraries, Blender's own code may be refactored or moved between files in a way that makes the per file copyright holders less meaningful. Copyright references to the "Blender Foundation" have been replaced with "Blender Authors", with the exception of `./extern/` since these this contains libraries which are more isolated, any changed to license headers there can be handled on a case-by-case basis. Some directories in `./intern/` have also been excluded: - `./intern/cycles/` it's own `AUTHORS` file is planned. - `./intern/opensubdiv/`. An "AUTHORS" file has been added, using the chromium projects authors file as a template. Design task: #110784 Ref !110783.
98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
/* SPDX-FileCopyrightText: 2015 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup depsgraph
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*/
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#include "intern/builder/deg_builder_transitive.h"
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#include "MEM_guardedalloc.h"
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#include "intern/node/deg_node.h"
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#include "intern/node/deg_node_component.h"
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#include "intern/node/deg_node_operation.h"
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#include "intern/debug/deg_debug.h"
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#include "intern/depsgraph.h"
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#include "intern/depsgraph_relation.h"
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namespace blender::deg {
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/* -------------------------------------------------- */
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/* Performs a transitive reduction to remove redundant relations.
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* https://en.wikipedia.org/wiki/Transitive_reduction
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*
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* XXX The current implementation is somewhat naive and has O(V*E) worst case
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* runtime.
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* A more optimized algorithm can be implemented later, e.g.
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*
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* http://www.sciencedirect.com/science/article/pii/0304397588900321/pdf?md5=3391e309b708b6f9cdedcd08f84f4afc&pid=1-s2.0-0304397588900321-main.pdf
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*
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* Care has to be taken to make sure the algorithm can handle the cyclic case
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* too! (unless we can to prevent this case early on).
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*/
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enum {
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OP_VISITED = 1,
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OP_REACHABLE = 2,
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};
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static void deg_graph_tag_paths_recursive(Node *node)
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{
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if (node->custom_flags & OP_VISITED) {
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return;
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}
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node->custom_flags |= OP_VISITED;
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for (Relation *rel : node->inlinks) {
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deg_graph_tag_paths_recursive(rel->from);
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/* Do this only in inlinks loop, so the target node does not get
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* flagged. */
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rel->from->custom_flags |= OP_REACHABLE;
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}
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}
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void deg_graph_transitive_reduction(Depsgraph *graph)
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{
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int num_removed_relations = 0;
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Vector<Relation *> relations_to_remove;
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for (OperationNode *target : graph->operations) {
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/* Clear tags. */
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for (OperationNode *node : graph->operations) {
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node->custom_flags = 0;
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}
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/* Mark nodes from which we can reach the target
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* start with children, so the target node and direct children are not
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* flagged. */
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target->custom_flags |= OP_VISITED;
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for (Relation *rel : target->inlinks) {
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deg_graph_tag_paths_recursive(rel->from);
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}
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/* Remove redundant paths to the target. */
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for (Relation *rel : target->inlinks) {
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if (rel->from->type == NodeType::TIMESOURCE) {
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/* HACK: time source nodes don't get "custom_flags" flag
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* set/cleared. */
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/* TODO: there will be other types in future, so iterators above
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* need modifying. */
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continue;
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}
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if (rel->from->custom_flags & OP_REACHABLE) {
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relations_to_remove.append(rel);
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}
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}
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for (Relation *rel : relations_to_remove) {
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rel->unlink();
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delete rel;
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}
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num_removed_relations += relations_to_remove.size();
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relations_to_remove.clear();
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}
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DEG_DEBUG_PRINTF((::Depsgraph *)graph, BUILD, "Removed %d relations\n", num_removed_relations);
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}
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} // namespace blender::deg
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