/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\ * This is GNU Go, a Go program. Contact gnugo@gnu.org, or see * * http://www.gnu.org/software/gnugo/ for more information. * * * * Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, * * 2008 and 2009 by the Free Software Foundation. * * * * 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 - version 3 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 in file COPYING 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., 51 Franklin Street, Fifth Floor, * * Boston, MA 02111, USA. * \* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ #include "gnugo.h" #include #include #include #include "liberty.h" #include "gg_utils.h" /* Forward declarations */ static int goal_dist(int pos, signed char goal[BOARDMAX]); static int compare_angles(const void *a, const void *b); static void show_surround_map(signed char mf[BOARDMAX], signed char mn[BOARDMAX]); /* Globals */ static int gg; /* stores the gravity center of the goal */ /* Returns true if a dragon is enclosed within the convex hull of * its hostile neighbor dragons. This is an indication that the dragon is * in danger. Stones on the second and first lines are not tested. * * Normally NULL will be passed to the parameter apos. It can be * an empty board location. If apos is non NULL it is marked and * added to the the hull. Thus we can ask if adding a single stone * to the board surrounds the dragon. * * A CORNER is a vertex of the polygon which comprises this convex * hull. The algorithm proceeds by first finding the sequence of * corners on the left side of the polyhedron, then the sequence * of corners on the right side. * * The hull is marked in the array mn with the number 1. A slight * expansion is marked with the number 2. Return code is SURROUNDED if * the friendly dragon lies within the area marked 1, * WEAKLY_SURROUNDED if it lies in the slightly larger area marked 1 * and 2, and 0 otherwise. * * The notion of weak surroundedness seems to be much less indicative * of a dragon's immanent danger than surroundedness. * * An exception: if the larger area contains any stone of a different * friendly dragon (which is not DEAD) the return code is 0, unless * that allied dragon is ENTIRELY contained within the hull. * * Another exception: an ikken tobi (one space jump) is generally not * a connection but in practice may be almost as good. If there is an * ikken tobi out of the hull, then the dragon is not surrounded. * * If the parameter showboard is 1, the figure is drawn. If showboard * is 2, the figure is only drawn if the region is surrounded. * * If (apos) is NULL, the result is saved in the surround_data cache. * The assumption is that the function will only be called once * with (apos) null, during make_dragons; thereafter the surroundedness * will be accessed using the function is_surrounded(). * * If *surround_size is not a NULL pointer, then surround_size * returns the size of the surroundings. */ int compute_surroundings(int pos, int apos, int showboard, int *surround_size) { int i, j; int m, n; int k; int dpos; int surrounded; int left_corner[MAX_BOARD]; int right_corner[MAX_BOARD]; int corner[BOARDMAX]; int left_corners = 0, right_corners = 0; int corners = 0; int top_row, bottom_row; int color = board[pos]; int other = OTHER_COLOR(color); int gi = 0; int gj = 0; int stones = 0; int found_some; signed char mf[BOARDMAX]; /* friendly dragon */ signed char mn[BOARDMAX]; /* neighbor dragons */ int sd[BOARDMAX]; /* distances to the goal */ if (DRAGON2(pos).hostile_neighbors == 0) return(0); memset(mf, 0, sizeof(mf)); memset(mn, 0, sizeof(mn)); memset(sd, 0, sizeof(sd)); mark_dragon(pos, mf, 1); /* mark hostile neighbors */ for (k = 0; k < DRAGON2(pos).neighbors; k++) { int nd = DRAGON(DRAGON2(pos).adjacent[k]).origin; if (board[nd] != color) { if (0) gprintf("neighbor: %1m\n", nd); mark_dragon(nd, mn, 1); } } /* descend markings from stones lying on the 2nd and third lines */ for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (ON_BOARD(dpos) && mn[dpos]) { for (k = 0; k < 4; k++) { int d = delta[k]; if (!ON_BOARD(dpos + d)) continue; if (!ON_BOARD(dpos + 2*d)) { if (board[dpos + d] == EMPTY) mn[dpos + d] = 1; } else if (!ON_BOARD(dpos + 3*d)) { if (board[dpos + d] == EMPTY && board[dpos + 2*d] == EMPTY) mn[dpos + 2*d] = 1; } } } /* compute minimum distances to the goal */ for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (ON_BOARD(dpos) && mn[dpos]) sd[dpos] = goal_dist(dpos, mf); /* revise markings */ do { found_some = 0; for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (ON_BOARD(dpos) && mn[dpos] && sd[dpos] > 8) { /* discard markings if we can find 2 stones * that verify : * - it is closer to the goal than we are * - it is closer to us than the goal is * - they are closer to each other than we are to the goal */ for (i = BOARDMIN; i < BOARDMAX; i++) if (ON_BOARD(i) && mn[i] && i != dpos && sd[i] < sd[dpos] && square_dist(i, dpos) < sd[dpos]) { for (j = i + 1; j < BOARDMAX; j++) if (ON_BOARD(j) && mn[j] && j != dpos && sd[j] < sd[dpos] && square_dist(j, dpos) < sd[dpos] && square_dist(i, j) < sd[dpos]) { mn[dpos] = 0; found_some = 1; break; } if (mn[dpos] == 0) break; } } } while (found_some); /* prepare corner array */ for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (ON_BOARD(dpos) && mn[dpos]) corner[corners++] = dpos; /* compute gravity center of the goal */ for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (ON_BOARD(dpos) && mf[dpos]) { gi += I(dpos); gj += J(dpos); stones++; } gi /= stones; gj /= stones; gg = POS(gi, gj); /* sort the corner array */ gg_sort(corner, corners, sizeof(int), compare_angles); /* if apos is not NO_MOVE, mark it. */ if (apos != NO_MOVE) { ASSERT_ON_BOARD1(apos); mn[apos] = 1; } if (showboard == 1) { show_surround_map(mf, mn); } /* find top row of surrounding polyhedron */ top_row = -1; for (m = 0; m < board_size; m++) { if (top_row != -1) break; for (n = 0; n < board_size; n++) if (mn[POS(m, n)]) { left_corner[0] = POS(m, n); top_row = m; break; } } /* find bottom row */ bottom_row = -1; for (m = board_size - 1; m >= 0; m--) { if (bottom_row != -1) break; for (n = 0; n < board_size; n++) if (mn[POS(m, n)]) { bottom_row = m; break; } } /* find the corners on the left side */ for (left_corners = 1; I(left_corner[left_corners-1]) < bottom_row; left_corners++) { int best_found = 0; float best_slope = 0.; int m = I(left_corner[left_corners-1]); int n = J(left_corner[left_corners-1]); for (i = m + 1; i <= bottom_row; i++) for (j = 0; j < board_size; j++) if (mn[POS(i, j)]) { float slope = ((float) (j - n))/((float) (i - m)); if (0) gprintf("(left) at %m, last %m, slope=%f\n", i, j, m, n, slope); if (!best_found || slope < best_slope) { best_found = POS(i, j); best_slope = slope; } } ASSERT_ON_BOARD1(best_found); left_corner[left_corners] = best_found; } for (n = board_size-1; n >= 0; n--) if (mn[POS(top_row, n)]) { right_corner[0] = POS(top_row, n); break; } /* find the corners on the right side */ for (right_corners = 1; I(right_corner[right_corners-1]) < bottom_row; right_corners++) { int best_found = 0; float best_slope = 0.; int m = I(right_corner[right_corners-1]); int n = J(right_corner[right_corners-1]); for (i = m + 1; i <= bottom_row; i++) { for (j = board_size - 1; j >= 0; j--) { if (mn[POS(i, j)]) { float slope = ((float) (j - n))/((float) (i - m)); if (0) gprintf("(right) at %m, last %m, slope=%f\n", i, j, m, n, slope); if (!best_found || slope > best_slope) { best_found = POS(i, j); best_slope = slope; } } } } ASSERT_ON_BOARD1(best_found); right_corner[right_corners] = best_found; } if (0) { for (k = 0; k < left_corners; k++) gprintf("left corner %d: %1m\n", k, left_corner[k]); for (k = 0; k < right_corners; k++) gprintf("right corner %d: %1m\n", k, right_corner[k]); } /* Now mark the interior of the convex hull */ for (n = J(left_corner[0]); n <= J(right_corner[0]); n++) mn[POS(top_row, n)] = 1; for (n = J(left_corner[left_corners-1]); n <= J(right_corner[right_corners-1]); n++) mn[POS(bottom_row, n)] = 1; for (m = top_row+1; m < bottom_row; m++) { int left_boundary = -1, right_boundary = -1; for (k = 1; k < left_corners; k++) { if (I(left_corner[k]) > m) { float ti = I(left_corner[k-1]); float tj = J(left_corner[k-1]); float bi = I(left_corner[k]); float bj = J(left_corner[k]); if (0) gprintf("(left) %d: %1m %1m\n", m, left_corner[k-1], left_corner[k]); /* left edge in this row is on segment (ti,tj) -> (bi, bj) */ /* FIXME: Rewrite this to avoid floating point arithmetic */ left_boundary = ceil(tj + (m - ti) * (bj - tj) / (bi - ti)); break; } } for (k = 1; k < right_corners; k++) { if (I(right_corner[k]) > m) { float ti = I(right_corner[k-1]); float tj = J(right_corner[k-1]); float bi = I(right_corner[k]); float bj = J(right_corner[k]); if (0) gprintf("(right) %d: %1m %1m\n", m, right_corner[k-1], right_corner[k]); /* FIXME: Rewrite this to avoid floating point arithmetic */ right_boundary = floor(tj + (m - ti) * (bj - tj) / (bi - ti)); break; } } for (n = left_boundary; n <= right_boundary; n++) mn[POS(m, n)] = 1; } /* mark the expanded region */ for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (ON_BOARD(dpos) && mn[dpos] == 1) for (k = 0; k < 4; k++) if (ON_BOARD(dpos + delta[k]) && !mn[dpos + delta[k]]) mn[dpos + delta[k]] = 2; /* Mark allied dragons that intersect the (unexpanded) hull. * These must all lie entirely within the hull for the * dragon to be considered surrounded. * * Only neighbor dragons are considered since dragons that * are not neighbors are less likely to be helpful. */ for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) { int mpos; if (ON_BOARD(dpos) && mn[dpos] == 1 && board[dpos] == color && are_neighbor_dragons(pos, dpos) && !mf[dpos]) { for (mpos = BOARDMIN; mpos < BOARDMAX; mpos++) if (ON_BOARD(mpos) && is_same_dragon(mpos, dpos)) mf[mpos] = 2; } /* A special case * * . X X . * X O . X * X . O O * . O . . * * The O stone hasn't been amalgamated and the surround computations * might think this single stone dragon is surrounded, which in turn * can generate overvaluation of moves around this stone. * Consequently, we allow inclusion of the stones at kosumi distance * in the mf (friendly) array. */ if (ON_BOARD(dpos) && mn[dpos] == 2 && board[dpos] == color && are_neighbor_dragons(pos, dpos) && !mf[dpos]) { for (k = 4; k < 8; k++) if (ON_BOARD(dpos + delta[k]) && board[dpos + delta[k]] == color && mn[dpos + delta[k]] == 1 && board[dpos + delta[k-4]] == EMPTY && board[dpos + delta[(k-3)%4]] == EMPTY) { for (mpos = BOARDMIN; mpos < BOARDMAX; mpos++) if (ON_BOARD(mpos) && is_same_dragon(mpos, dpos)) mf[mpos] = 2; } } } /* determine the surround status of the dragon */ surrounded = SURROUNDED; /* Compute the maximum surround status awarded * If distances between enclosing stones are large, reduce to * WEAKLY_SURROUNDED. If (really) too large, then reduce to 0 * FIXME: constants chosen completely ad hoc. Possibly better tunings * can be found. */ for (k = 0; k < corners - 1; k++) { if (is_edge_vertex(corner[k]) && is_edge_vertex(corner[k+1])) continue; if (square_dist(corner[k], corner[k+1]) > 60) { surrounded = 0; break; } else if (square_dist(corner[k], corner[k+1]) > 27) surrounded = WEAKLY_SURROUNDED; } if (surrounded && (!is_edge_vertex(corner[0]) || !is_edge_vertex(corner[corners-1]))) { if (square_dist(corner[0], corner[corners-1]) > 60) surrounded = 0; else if (square_dist(corner[0], corner[corners-1]) > 27) surrounded = WEAKLY_SURROUNDED; } if (surrounded) for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) if (mf[dpos]) { if (mn[dpos] == 0) { surrounded = 0; break; } else if (mn[dpos] == 2) surrounded = WEAKLY_SURROUNDED; } /* revise the status for single stone dragons. */ if (stones == 1 && surrounded == WEAKLY_SURROUNDED && mn[pos] == 2) surrounded = 0; /* revise the status if an ikken tobi jumps out. */ if (surrounded) { for (dpos = BOARDMIN; dpos < BOARDMAX && surrounded; dpos++) { if (!ON_BOARD(dpos) || !mf[dpos]) continue; for (k = 0; k < 4; k++) { int up = delta[k]; int right = delta[(k + 1) % 4]; if (board[dpos + up] == EMPTY && board[dpos + 2*up] == color && mn[dpos + 2*up] != 1 && ON_BOARD(dpos + up + right) && board[dpos + up + right] != other && ON_BOARD(dpos + up - right) && board[dpos + up - right] != other) { surrounded = 0; break; } } } } if (showboard == 1 || (showboard == 2 && surrounded)) { show_surround_map(mf, mn); } if (!apos && surrounded && surround_pointer < MAX_SURROUND) { memcpy(surroundings[surround_pointer].surround_map, mn, sizeof(mn)); surroundings[surround_pointer].dragon_number = dragon[pos].id; surround_pointer++; } if (surround_size) { int pos; *surround_size = 0; for (pos = BOARDMIN; pos < BOARDMAX; pos++) if (ON_BOARD(pos) && mn[pos] == 1) (*surround_size)++; } return surrounded; } /* Computes the minimum distance to the goal */ static int goal_dist(int pos, signed char goal[BOARDMAX]) { int dist = 10000; int ii; for (ii = BOARDMIN; ii < BOARDMAX; ii++) if (ON_BOARD(ii) && goal[ii]) dist = gg_min(dist, square_dist(ii, pos)); return dist; } /* Compares angles. Chosen convention: * - SOUTH is "lowest" * - ascending order is done clock-wise (WEST, NORTH, EAST) */ static int compare_angles(const void *a, const void *b) { int aa = *((const int *)a); int bb = *((const int *)b); int di_a = I(aa) - I(gg); int dj_a = J(aa) - J(gg); int di_b = I(bb) - I(gg); int dj_b = J(bb) - J(gg); float sin_a, sin_b; if (aa == gg) return 1; if (bb == gg) return -1; if (dj_a == 0) { if (di_a > 0) { if (dj_b != 0 || di_b <= 0) return -1; return 0; } else { if (dj_b > 0) return -1; else if (dj_b < 0 || di_b > 0) return 1; else return 0; } } sin_a = (float)di_a / sqrt(di_a*di_a + dj_a*dj_a); sin_b = (float)di_b / sqrt(di_b*di_b + dj_b*dj_b); if (dj_a > 0) { if (dj_b <= 0) return 1; if (sin_a > sin_b) return 1; else if (sin_a < sin_b) return -1; else return 0; } else { /* if (dj_a < 0) */ if (dj_b > 0) return -1; if (sin_a < sin_b) return 1; else if (sin_a > sin_b) return -1; else return 0; } } static void show_surround_map(signed char mf[BOARDMAX], signed char mn[BOARDMAX]) { int m, n; start_draw_board(); for (m = 0; m < board_size; m++) for (n = 0; n < board_size; n++) { int col, c; if (mf[POS(m, n)]) { if (mn[POS(m, n)] == 1) col = GG_COLOR_RED; else if (mn[POS(m, n)] == 2) col = GG_COLOR_YELLOW; else col = GG_COLOR_GREEN; } else if (mn[POS(m, n)] == 1) col = GG_COLOR_BLUE; else if (mn[POS(m, n)] == 2) col = GG_COLOR_CYAN; else col = GG_COLOR_BLACK; if (board[POS(m, n)] == BLACK) c = 'X'; else if (board[POS(m, n)] == WHITE) c = 'O'; else if (mn[POS(m, n)]) c = '*'; else c = '.'; draw_color_char(m, n, c, col); } end_draw_board(); } int is_surrounded(int dr) { return(DRAGON2(dr).surround_status); } /* Returns true if (dragon) is not surrounded, but (move) surrounds it. */ int does_surround(int move, int dr) { if (DRAGON2(dr).surround_status) return 0; return compute_surroundings(dr, move, 0, NULL); } /* Should be run once per genmove, before make_dragons. */ void reset_surround_data(void) { surround_pointer = 0; } /* Returns 1 (respectively 2) if pos is in the convex hull * (respectively expanded hull boundary) of the surrounding * dragons. Returns -1 if the dragon is not found. */ int surround_map(int dr, int pos) { int k; for (k = 0; k < surround_pointer; k++) if (surroundings[k].dragon_number == dragon[dr].id) return surroundings[k].surround_map[pos]; return -1; } /* * Local Variables: * tab-width: 8 * c-basic-offset: 2 * End: */