154 lines
4.6 KiB
C
154 lines
4.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright 2014 Blender Foundation */
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#pragma once
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/** \file
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* \ingroup bli
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* \brief An implementation of the A* (AStar) algorithm to solve shortest path problem.
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*/
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#include "BLI_utildefines.h"
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#include "BLI_bitmap.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* -------------------------------------------------------------------- */
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typedef struct BLI_AStarGNLink {
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int nodes[2];
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float cost;
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void *custom_data;
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} BLI_AStarGNLink;
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typedef struct BLI_AStarGNode {
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struct ListBase neighbor_links;
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void *custom_data;
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} BLI_AStarGNode;
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typedef struct BLI_AStarSolution {
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/* Final 'most useful' data. */
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/** Number of steps (i.e. walked links) in path
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* (nodes num, including start and end, is steps + 1). */
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int steps;
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/** Store the path, in reversed order (from destination to source node), as indices. */
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int *prev_nodes;
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/** Indices are nodes' ones, as prev_nodes, but they map to relevant link. */
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BLI_AStarGNLink **prev_links;
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void *custom_data;
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/* Mostly runtime data. */
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BLI_bitmap *done_nodes;
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float *g_costs;
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int *g_steps;
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struct MemArena *mem; /* Memory arena. */
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} BLI_AStarSolution;
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typedef struct BLI_AStarGraph {
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int node_num;
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BLI_AStarGNode *nodes;
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void *custom_data;
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struct MemArena *mem; /* Memory arena. */
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} BLI_AStarGraph;
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/**
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* Initialize a node in A* graph.
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*
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* \param custom_data: an opaque pointer attached to this link,
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* available e.g. to cost callback function.
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*/
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void BLI_astar_node_init(BLI_AStarGraph *as_graph, int node_index, void *custom_data);
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/**
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* Add a link between two nodes of our A* graph.
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*
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* \param cost: The 'length' of the link
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* (actual distance between two vertices or face centers e.g.).
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* \param custom_data: An opaque pointer attached to this link,
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* available e.g. to cost callback function.
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*/
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void BLI_astar_node_link_add(
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BLI_AStarGraph *as_graph, int node1_index, int node2_index, float cost, void *custom_data);
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/**
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* \return The index of the other node of given link.
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*/
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int BLI_astar_node_link_other_node(BLI_AStarGNLink *lnk, int idx);
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/**
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* Initialize a solution data for given A* graph. Does not compute anything!
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*
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* \param custom_data: an opaque pointer attached to this link, available e.g
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* . to cost callback function.
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*
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* \note BLI_AStarSolution stores nearly all data needed during solution compute.
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*/
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void BLI_astar_solution_init(BLI_AStarGraph *as_graph,
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BLI_AStarSolution *as_solution,
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void *custom_data);
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/**
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* Clear given solution's data, but does not release its memory.
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* Avoids having to recreate/allocate a memory-arena in loops, e.g.
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*
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* \note This *has to be called* between each path solving.
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*/
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void BLI_astar_solution_clear(BLI_AStarSolution *as_solution);
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/**
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* Release the memory allocated for this solution.
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*/
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void BLI_astar_solution_free(BLI_AStarSolution *as_solution);
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/**
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* Callback computing the current cost (distance) to next node,
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* and the estimated overall cost to destination node
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* (A* expects this estimation to always be less or equal than actual shortest path
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* from next node to destination one).
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*
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* \param link: the graph link between current node and next one.
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* \param node_idx_curr: current node index.
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* \param node_idx_next: next node index.
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* \param node_idx_dst: destination node index.
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*/
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typedef float (*astar_f_cost)(BLI_AStarGraph *as_graph,
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BLI_AStarSolution *as_solution,
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BLI_AStarGNLink *link,
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int node_idx_curr,
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int node_idx_next,
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int node_idx_dst);
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/**
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* Initialize an A* graph. Total number of nodes must be known.
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*
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* Nodes might be e.g. vertices, faces, ... etc.
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*
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* \param custom_data: an opaque pointer attached to this link,
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* available e.g. to cost callback function.
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*/
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void BLI_astar_graph_init(BLI_AStarGraph *as_graph, int node_num, void *custom_data);
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void BLI_astar_graph_free(BLI_AStarGraph *as_graph);
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/**
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* Solve a path in given graph, using given 'cost' callback function.
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*
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* \param max_steps: maximum number of nodes the found path may have.
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* Useful in performance-critical usages.
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* If no path is found within given steps, returns false too.
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* \return true if a path was found, false otherwise.
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*/
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bool BLI_astar_graph_solve(BLI_AStarGraph *as_graph,
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int node_index_src,
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int node_index_dst,
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astar_f_cost f_cost_cb,
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BLI_AStarSolution *r_solution,
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int max_steps);
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#ifdef __cplusplus
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}
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#endif
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