/* path.c */ /* robospierre - Eurobot 2011 AI. {{{ * * Copyright (C) 2011 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_2011.h" #include "element.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. * * The grid is composed of 11 columns of 4 node each. They are numbered by * column. Even columns are aligned with center of squares, while odd columns * are at squares intersections. Therefore, odd columns have a offset of * 352/2 mm, and that is the reason why code should handle odd and even * columns differently. * * There is also extra grid nodes in front of the green zone. * * All those tricks are used to reduce the number of nodes. */ /** Number of possible obstacles. */ #define PATH_OBSTACLES_NB AC_PATH_OBSTACLES_NB /** Number of nodes in a column. */ #define PATH_COLUMN_NODES_NB 4 /** Number of columns. */ #define PATH_COLUMNS_NB 11 /** Number of nodes in the grid. */ #define PATH_GRID_NODES_NB (PATH_COLUMNS_NB * PATH_COLUMN_NODES_NB) /** Number of nodes in front of each green zone. */ #define PATH_GREEN_NODES_NB 4 /** Number of fixed nodes. */ #define PATH_FIXED_NODES_NB (PATH_GRID_NODES_NB + 2 * PATH_GREEN_NODES_NB) /** 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 }, /* 0 column 0. */ { 1 }, /* 1 */ { 1 }, /* 2 */ { 1 }, /* 3 */ { 1 }, /* 4 column 1. */ { 1 }, /* 5 */ { 1 }, /* 6 */ { 1 }, /* 7 */ { 1 }, /* 8 column 2. */ { 1 }, /* 9 */ { 1 }, /* 10 */ { 1 }, /* 11 */ { 1 }, /* 12 column 3. */ { 1 }, /* 13 */ { 1 }, /* 14 */ { 1 }, /* 15 */ { 1 }, /* 16 column 4. */ { 1 }, /* 17 */ { 1 }, /* 18 */ { 1 }, /* 19 */ { 1 }, /* 20 column 5. */ { 1 }, /* 21 */ { 1 }, /* 22 */ { 1 }, /* 23 */ { 1 }, /* 24 column 6. */ { 1 }, /* 25 */ { 1 }, /* 26 */ { 1 }, /* 27 */ { 1 }, /* 28 column 7. */ { 1 }, /* 29 */ { 1 }, /* 30 */ { 1 }, /* 31 */ { 1 }, /* 32 column 8. */ { 1 }, /* 33 */ { 1 }, /* 34 */ { 1 }, /* 35 */ { 1 }, /* 36 column 9. */ { 1 }, /* 37 */ { 1 }, /* 38 */ { 1 }, /* 39 */ { 1 }, /* 40 column 10. */ { 1 }, /* 41 */ { 1 }, /* 42 */ { 1 }, /* 43 */ { 1 }, /* 44 left green. */ { 1 }, /* 45 */ { 1 }, /* 46 */ { 1 }, /* 47 */ { 1 }, /* 48 right green. */ { 1 }, /* 49 */ { 1 }, /* 50 */ { 1 }, /* 51 */ /* }}} */ }; /** Compute position of a node. */ static void path_pos (uint8_t node, vect_t *pos) { assert (node < PATH_NODES_NB); if (node < PATH_GRID_NODES_NB) { uint8_t col = node / PATH_COLUMN_NODES_NB; uint8_t line = node - col * PATH_COLUMN_NODES_NB; pos->x = 400 + 50 + 350 / 2 + col * 350 / 2; pos->y = 2100 - 350 - 350 / 2 + (col % 2 ? 350 / 2 : 0) - line * 350; } else if (node < PATH_GRID_NODES_NB + 2 * PATH_GREEN_NODES_NB) { node -= PATH_GRID_NODES_NB; uint8_t col = node / PATH_GREEN_NODES_NB; uint8_t line = node - col * PATH_GREEN_NODES_NB; pos->x = col == 0 ? BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM : PG_WIDTH - BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM; pos->y = (5 - line) * 280 + 10; } else { *pos = path.endpoints[node - PATH_FIXED_NODES_NB]; } } static uint8_t path_element_blocking (uint8_t node, uint8_t escape) { vect_t pos; path_pos (node, &pos); int16_t square_x = (pos.x - 450 - 1) / 350; int16_t square_y = (2100 - pos.y - 1) / 350; uint8_t element_id = ELEMENT_UNLOAD_START + square_x + 6 * square_y; if (element_blocking (element_id, escape)) return 1; uint8_t intersection = ((pos.x - 450) / 350) != square_x; if (intersection) { if (element_blocking (element_id + 1, escape)) return 1; if (element_blocking (element_id + 6, escape)) return 1; if (element_blocking (element_id + 6 + 1, escape)) return 1; } return 0; } /** 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 green zone. */ uint8_t a_green, b_green; a_green = va.x < PG_GREEN_WIDTH_MM || va.x > PG_WIDTH - PG_GREEN_WIDTH_MM; b_green = vb.x < PG_GREEN_WIDTH_MM || vb.x > PG_WIDTH - PG_GREEN_WIDTH_MM; if ((va.x < BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM && vb.x > BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM) || (va.x > BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM && vb.x < BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM) || (va.x > PG_WIDTH - BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM && vb.x < PG_WIDTH - BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM) || (va.x < PG_WIDTH - BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM && vb.x > PG_WIDTH - BOT_GREEN_ELEMENT_PLACE_DISTANCE_MM)) return 1; if (a_green && b_green) return 1; if (a_green || b_green) factor = 4; /* Test for protected zone. */ if (va.y <= 350 && va.x > PG_WIDTH / 2 - 350 && va.y < PG_WIDTH / 2 + 350 && (vb.x < PG_WIDTH / 2 - 350 || vb.x > PG_WIDTH / 2 + 350)) return 1; if (vb.y <= 350 && vb.x > PG_WIDTH / 2 - 350 && vb.y < PG_WIDTH / 2 + 350 && (va.x < PG_WIDTH / 2 - 350 || va.x > PG_WIDTH / 2 + 350)) return 1; /* 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; } /* Test for a blocking element. */ if (element_blocking_path (va, vb, d, path.escape_factor)) blocking = 1; /* Handle escaping. */ 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 || path_element_blocking (i, path.escape_factor)) 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 nodes in grid. */ static uint8_t path_astar_neighbor_callback_grid (uint8_t node, struct astar_neighbor_t *neighbors) { uint8_t neighbors_nb = 0; uint8_t i; /* Add neighbors in all 8 directions. */ static const struct { /** Column offset of this neighbor. */ int8_t column_offset; /** Line offset of this neighbor, for even columns. */ int8_t even_line_offset; /** Line offset for odd columns. */ int8_t odd_line_offset; /** Distance to this neighbor. */ uint16_t weight; } star_n[] = { { 0, -1, -1, 350 }, /* N */ { -1, 0, -1, 248 }, /* NW */ { -2, 0, 0, 350 }, /* W */ { -1, 1, 0, 248 }, /* SW */ { 0, 1, 1, 350 }, /* S */ { 1, 1, 0, 248 }, /* SE */ { 2, 0, 0, 350 }, /* E */ { 1, 0, -1, 248 }, /* NE */ }; uint8_t col = node / PATH_COLUMN_NODES_NB; uint8_t line = node - col * PATH_COLUMN_NODES_NB; uint8_t odd = col % 2; for (i = 0; i < UTILS_COUNT (star_n); i++) { int8_t new_col = col + star_n[i].column_offset; int8_t new_line = line + (odd ? star_n[i].odd_line_offset : star_n[i].even_line_offset); int8_t new_node = new_col * PATH_COLUMN_NODES_NB + new_line; if (new_col >= 0 && new_col < PATH_COLUMNS_NB && new_line >= 0 && new_line < PATH_COLUMN_NODES_NB) { uint8_t valid = path.valid[new_node]; if (valid) { neighbors[neighbors_nb].node = new_node; neighbors[neighbors_nb].weight = star_n[i].weight + 1; neighbors_nb++; } } } /* Check path to green nodes. */ int16_t d; if (col <= 1 || col >= PATH_COLUMNS_NB - 1) { uint8_t green = PATH_GRID_NODES_NB + (col <= 1 ? 0 : PATH_GREEN_NODES_NB); for (i = green; i < green + PATH_GREEN_NODES_NB; i++) { if (!path_blocking (node, i, &d)) { neighbors[neighbors_nb].node = i; neighbors[neighbors_nb].weight = d + 1; neighbors_nb++; } } } /* 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 green nodes. */ static uint8_t path_astar_neighbor_callback_green (uint8_t node, struct astar_neighbor_t *neighbors) { uint8_t neighbors_nb = 0; uint8_t i; uint8_t col = (node - PATH_GRID_NODES_NB) / PATH_GREEN_NODES_NB; int16_t d; /* Check path to grid nodes. */ uint8_t grid = col ? PATH_GRID_NODES_NB - 2 * PATH_COLUMN_NODES_NB : 0; for (i = grid; i < grid + 2 * PATH_COLUMN_NODES_NB; i++) { if (!path_blocking (node, i, &d)) { neighbors[neighbors_nb].node = i; neighbors[neighbors_nb].weight = d + 1; neighbors_nb++; } } /* Check path to other green nodes. */ uint8_t green = PATH_GRID_NODES_NB + (col ? PATH_GREEN_NODES_NB : 0); for (i = green; i < green + PATH_GREEN_NODES_NB; i++) { if (i != node && !path_blocking (node, i, &d)) { neighbors[neighbors_nb].node = i; neighbors[neighbors_nb].weight = d + 1; neighbors_nb++; } } /* 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_GRID_NODES_NB) return path_astar_neighbor_callback_grid (node, neighbors); else if (node < PATH_GRID_NODES_NB + 2 * PATH_GREEN_NODES_NB) return path_astar_neighbor_callback_green (node, neighbors); else return path_astar_neighbor_callback_endpoints (node, neighbors); } uint16_t path_astar_heuristic_callback (uint8_t node) { /* TODO: a better and faster heuristic can be found, considering that * movement is only allowed on the grid. */ vect_t pos; path_pos (node, &pos); return distance_point_point (&pos, &path.endpoints[0]); }