diff options
Diffstat (limited to 'crawl-ref/source/travel.cc')
| -rw-r--r-- | crawl-ref/source/travel.cc | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/crawl-ref/source/travel.cc b/crawl-ref/source/travel.cc index f54a28869a..08abb41ec7 100644 --- a/crawl-ref/source/travel.cc +++ b/crawl-ref/source/travel.cc @@ -1437,10 +1437,22 @@ coord_def travel_pathfind::pathfind(run_mode_type rmode) ignore_hostile = false; - // Set the seed point + // Set the seed point. + // For each round, circumference will store all points that were discovered + // in the previous round of a given distance. We use an array of size 2, + // so we can comfortably switch between the list of points to be + // investigated this round and the slowly growing list of points to be + // inspected next round. Once we've finished with the current round, i.e. + // there are no more points to be looked at in the current array, we switch + // circ_index over to !circ_index (between 0 and 1), so the "next round" + // becomes the current one, and the old points can be overwritten with + // newer ones. Since we count the number of points for next round in + // next_iter_points, we don't even need to reset the array. circumference[circ_index][0] = start; // Zap out previous distances array + // point_distance will hold the distance of all points from the starting + // point, i.e. the distance travelled to get there. memset(point_distance, 0, sizeof(travel_distance_grid_t)); for ( ; points > 0; ++traveled_distance, circ_index = !circ_index, @@ -1448,6 +1460,9 @@ coord_def travel_pathfind::pathfind(run_mode_type rmode) { for (int i = 0; i < points; ++i) { + // Look at all neighbours of the current grid. + // path_examine_point() returns true if the target is reached + // and marked as such. if (path_examine_point(circumference[circ_index][i])) { return (runmode == RMODE_TRAVEL ? travel_move() @@ -1455,6 +1470,8 @@ coord_def travel_pathfind::pathfind(run_mode_type rmode) } } + // If there are no more points to look at, we're done, but we did + // not find a path to our target. if (next_iter_points == 0) { // Don't reseed unless we've found no target for explore, OR @@ -1671,8 +1688,7 @@ void travel_pathfind::good_square(const coord_def &c) { if (!point_distance[c.x][c.y]) { - // This point is going to be on the agenda for the next - // iteration + // This point is going to be on the agenda for the next iteration. circumference[!circ_index][next_iter_points++] = c; point_distance[c.x][c.y] = traveled_distance; } @@ -1691,6 +1707,9 @@ bool travel_pathfind::point_traverse_delay(const coord_def &c) return (false); } +// Checks all neighbours of c, adds them to next round's list of points +// - happens in path_flood() - and returns true if one of them turns out +// to be the target; otherwise, false. bool travel_pathfind::path_examine_point(const coord_def &c) { if (point_traverse_delay(c)) |