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+/* 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]);
+}