/* path.c */ /* guybrush - Eurobot 2012 AI. {{{ * * Copyright (C) 2012 Nicolas Schodet * * APBTeam: * Web: http://apbteam.org/ * Email: team AT apbteam DOT org * * 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * }}} */ #include "common.h" #include "defs.h" #include "path.h" #include "bot.h" #include "playground_2012.h" #include "modules/path/astar/astar.h" #include "modules/utils/utils.h" #include "modules/math/geometry/distance.h" #define PATH_DEBUG 0 #if PATH_DEBUG #include "debug.host.h" #endif /** * This year, due to the large number of obstacles, a grid like structure is * used for path finding on the playground. The A* algorithm is used to find * path along nodes. * * TODO: this is a placeholder for the future algorithm. */ /** Number of possible obstacles. */ #define PATH_OBSTACLES_NB AC_PATH_OBSTACLES_NB /** Number of fixed nodes. */ #define PATH_FIXED_NODES_NB (1) /** Number of nodes in search graph, last two nodes are destination and source * nodes. */ #define PATH_NODES_NB (PATH_FIXED_NODES_NB + 2) /** Index of destination node. */ #define PATH_DST_NODE_INDEX PATH_FIXED_NODES_NB /** Index of source node. */ #define PATH_SRC_NODE_INDEX (PATH_DST_NODE_INDEX + 1) /** Information on a node. */ struct path_node_t { /** Whether this node can be used. */ uint8_t usable; }; /** Context. */ struct path_t { /** List of obstacles. */ struct path_obstacle_t obstacles[PATH_OBSTACLES_NB]; /** Escape factor, 0 if none. */ uint8_t escape_factor; /** List of nodes used for A*. */ struct astar_node_t astar_nodes[PATH_NODES_NB]; /** Cache of whether a node is blocked. */ uint8_t valid[PATH_FIXED_NODES_NB]; /** Position of end points. */ vect_t endpoints[2]; /** Whether the last update was a success. */ uint8_t found; /** Which node to look at for next step. */ uint8_t get; }; static struct path_t path; /** Static information on nodes. */ static const struct path_node_t path_nodes[PATH_FIXED_NODES_NB] = { /* {{{ */ { 1 }, /* }}} */ }; /** Compute position of a node. */ static void path_pos (uint8_t node, vect_t *pos) { assert (node < PATH_NODES_NB); if (node < PATH_FIXED_NODES_NB) { /* Temporary nonsense node. */ pos->x = PG_WIDTH / 2; pos->y = PG_LENGTH / 2; } else { *pos = path.endpoints[node - PATH_FIXED_NODES_NB]; } } /** Return 1 if the direct path between a and b nodes is blocked, also compute * distance. */ static uint8_t path_blocking (uint8_t a, uint8_t b, int16_t *dp) { uint8_t i; vect_t va; vect_t vb; uint8_t escape_factor = 0; uint8_t factor = 1; uint8_t blocking = 0; if (a == PATH_SRC_NODE_INDEX || b == PATH_SRC_NODE_INDEX) escape_factor = path.escape_factor; path_pos (a, &va); path_pos (b, &vb); /* Test for a blocking obstacle. */ for (i = 0; i < PATH_OBSTACLES_NB && !blocking; i++) { if (path.obstacles[i].valid) { uint16_t d = distance_segment_point (&va, &vb, &path.obstacles[i].c); if (d < path.obstacles[i].r) blocking = 1; } } /* Compute distance. */ int16_t d = distance_point_point (&va, &vb); if (d == 0) { *dp = 0; return 0; } /* Handle escaping. */ /* TODO: do not escape through a totem! */ if (blocking) { if (escape_factor) { *dp = d * escape_factor; return 0; } else return 1; } /* No blocking. */ *dp = d * factor; return 0; } /** Update the cache of blocked nodes. */ static void path_blocked_update (void) { uint8_t i, j; for (i = 0; i < PATH_FIXED_NODES_NB; i++) { uint8_t valid = 1; /* First, gather information from tables. */ if (!path_nodes[i].usable) valid = 0; else { vect_t pos; path_pos (i, &pos); /* Then, test for obstacles. */ for (j = 0; j < PATH_OBSTACLES_NB; j++) { if (path.obstacles[j].valid) { vect_t v = pos; vect_sub (&v, &path.obstacles[j].c); uint32_t dsq = vect_dot_product (&v, &v); uint32_t r = path.obstacles[j].r; if (dsq <= r * r) { valid = 0; break; } } } } /* Update cache. */ path.valid[i] = valid; } } void path_init (void) { } void path_endpoints (vect_t s, vect_t d) { path.endpoints[0] = d; path.endpoints[1] = s; } void path_escape (uint8_t factor) { path.escape_factor = factor; } void path_obstacle (uint8_t i, vect_t c, uint16_t r, uint8_t factor, uint16_t valid) { assert (i < AC_PATH_OBSTACLES_NB); assert (factor == 0); path.obstacles[i].c = c; path.obstacles[i].r = r; path.obstacles[i].valid = valid; } void path_decay (void) { uint8_t i; for (i = 0; i < PATH_OBSTACLES_NB; i++) { if (path.obstacles[i].valid && path.obstacles[i].valid != PATH_OBSTACLE_VALID_ALWAYS) path.obstacles[i].valid--; } } void path_update (void) { path_blocked_update (); path.found = astar (path.astar_nodes, PATH_NODES_NB, PATH_DST_NODE_INDEX, PATH_SRC_NODE_INDEX); path.get = PATH_SRC_NODE_INDEX; #if AC_PATH_REPORT if (path.found) { uint8_t n, len = 0; vect_t points[PATH_NODES_NB]; for (n = path.get; n != PATH_DST_NODE_INDEX; n = path.astar_nodes[n].prev) path_pos (n, &points[len++]); path_pos (n, &points[len++]); AC_PATH_REPORT_CALLBACK (points, len, path.obstacles, PATH_OBSTACLES_NB); } #endif } uint8_t path_get_next (vect_t *p) { if (path.found) { assert (path.get != PATH_DST_NODE_INDEX); uint8_t prev = path.get; vect_t pp; path_pos (prev, &pp); uint8_t next = path.astar_nodes[path.get].prev; path.get = next; path_pos (next, p); while (next != 0xff) { /* Try to remove useless points. */ uint8_t next = path.astar_nodes[path.get].prev; if (next == 0xff || next == PATH_DST_NODE_INDEX) break; vect_t np; path_pos (next, &np); vect_t vnp = np; vect_sub (&vnp, &pp); vect_t vp = *p; vect_sub (&vp, &pp); if (vect_normal_dot_product (&vp, &vnp) == 0) { path.get = next; *p = np; } else break; } return 1; } else return 0; } /** Neighbors callback for fixed nodes. */ static uint8_t path_astar_neighbor_callback_fixed (uint8_t node, struct astar_neighbor_t *neighbors) { uint8_t neighbors_nb = 0; int16_t d; /* Check if direct path OK. */ if (!path_blocking (node, PATH_SRC_NODE_INDEX, &d)) { /* Add this neighbor. */ neighbors[neighbors_nb].node = PATH_SRC_NODE_INDEX; neighbors[neighbors_nb].weight = d + 1; neighbors_nb++; } #if PATH_DEBUG for (i = 0; i < neighbors_nb; i++) DPRINTF (" n %d %d\n", neighbors[i].node, neighbors[i].weight); #endif return neighbors_nb; } /** Neighbors callback for endpoints. */ static uint8_t path_astar_neighbor_callback_endpoints (uint8_t node, struct astar_neighbor_t *neighbors) { uint8_t neighbors_nb = 0; uint8_t i; assert (node == PATH_DST_NODE_INDEX); /* Select neighbors in the fixed nodes. */ for (i = 0; i < PATH_FIXED_NODES_NB; i++) { /* Discard blocking nodes. */ if (!path.valid[i]) continue; /* Check if there is an obstacle along the path. */ int16_t d; if (path_blocking (PATH_DST_NODE_INDEX, i, &d)) continue; /* Add this neighbor. */ neighbors[neighbors_nb].node = i; neighbors[neighbors_nb].weight = d + 1; neighbors_nb++; } /* Check if direct path OK. */ int16_t d; if (!path_blocking (PATH_DST_NODE_INDEX, PATH_SRC_NODE_INDEX, &d)) { /* Add this neighbor. */ neighbors[neighbors_nb].node = PATH_SRC_NODE_INDEX; neighbors[neighbors_nb].weight = d + 1; neighbors_nb++; } #if PATH_DEBUG for (i = 0; i < neighbors_nb; i++) DPRINTF (" n %d %d\n", neighbors[i].node, neighbors[i].weight); #endif return neighbors_nb; } uint8_t path_astar_neighbor_callback (uint8_t node, struct astar_neighbor_t *neighbors) { #if PATH_DEBUG DPRINTF ("neighbor %d\n", node); #endif if (node < PATH_FIXED_NODES_NB) return path_astar_neighbor_callback_fixed (node, neighbors); else return path_astar_neighbor_callback_endpoints (node, neighbors); } uint16_t path_astar_heuristic_callback (uint8_t node) { vect_t pos; path_pos (node, &pos); return distance_point_point (&pos, &path.endpoints[0]); }