Split monster_pathfind out into mon-pathfind.cc.

1 files changed, 5 insertions, 527 deletions

diff --git a/crawl-ref/source/mon-place.cc b/crawl-ref/source/mon-place.cc
index 57990844ff..e03177d26d 100644
--- a/crawl-ref/source/mon-place.cc
+++ b/crawl-ref/source/mon-place.cc
@@ -124,7 +124,7 @@ bool monster_habitable_grid(const monsters *m,
                                    m->cannot_move()));
 }
 
-inline static bool _mons_airborne(int mcls, int flies, bool paralysed)
+bool mons_airborne(int mcls, int flies, bool paralysed)
 {
     if (flies == -1)
         flies = mons_class_flies(mcls);
@@ -171,7 +171,7 @@ bool monster_habitable_grid(monster_type montype,
     // [dshaligram] Flying creatures are all DNGN_FLOOR, so we
     // only have to check for the additional valid grids of deep
     // water and lava.
-    if (_mons_airborne(montype, flies, paralysed)
+    if (mons_airborne(montype, flies, paralysed)
         && (actual_grid == DNGN_LAVA || actual_grid == DNGN_DEEP_WATER))
     {
         return (true);
@@ -467,7 +467,7 @@ monster_type pick_random_monster(const level_id &place, int power,
     return (mon_type);
 }
 
-static bool _can_place_on_trap(int mon_type, trap_type trap)
+bool can_place_on_trap(int mon_type, trap_type trap)
 {
     if (trap == TRAP_TELEPORT)
         return (false);
@@ -544,7 +544,7 @@ static monster_type _resolve_monster_type(monster_type mon_type,
 
                 // Don't generate monsters on top of teleport traps.
                 const trap_def* ptrap = find_trap(pos);
-                if (ptrap && !_can_place_on_trap(mon_type, ptrap->type))
+                if (ptrap && !can_place_on_trap(mon_type, ptrap->type))
                     continue;
 
                 // Check whether there's a stair
@@ -713,7 +713,7 @@ static bool _valid_monster_generation_location(
     // Don't generate monsters on top of teleport traps.
     // (How did they get there?)
     const trap_def* ptrap = find_trap(mg_pos);
-    if (ptrap && !_can_place_on_trap(mg.cls, ptrap->type))
+    if (ptrap && !can_place_on_trap(mg.cls, ptrap->type))
         return (false);
 
     return (true);
@@ -2981,528 +2981,6 @@ monster_type summon_any_dragon(dragon_class_type dct)
 }
 
 /////////////////////////////////////////////////////////////////////////////
-// monster_pathfind
-
-// The pathfinding is an implementation of the A* algorithm. Beginning at the
-// destination square we check all neighbours of a given grid, estimate the
-// distance needed for any shortest path including this grid and push the
-// result into a hash. We can then easily access all points with the shortest
-// distance estimates and then check _their_ neighbours and so on.
-// The algorithm terminates once we reach the monster position since - because
-// of the sorting of grids by shortest distance in the hash - there can be no
-// path between start and target that is shorter than the current one. There
-// could be other paths that have the same length but that has no real impact.
-// If the hash has been cleared and the start grid has not been encountered,
-// then there's no path that matches the requirements fed into monster_pathfind.
-// (These requirements are usually preference of habitat of a specific monster
-// or a limit of the distance between start and any grid on the path.)
-
-int mons_tracking_range(const monsters *mon)
-{
-
-    int range = 0;
-    switch (mons_intel(mon))
-    {
-    case I_PLANT:
-        range = 2;
-        break;
-    case I_INSECT:
-        range = 4;
-        break;
-    case I_ANIMAL:
-        range = 5;
-        break;
-    case I_NORMAL:
-        range = LOS_RADIUS;
-        break;
-    default:
-        // Highly intelligent monsters can find their way
-        // anywhere. (range == 0 means no restriction.)
-        break;
-    }
-
-    if (range)
-    {
-        if (mons_is_native_in_branch(mon))
-            range += 3;
-        else if (mons_class_flag(mon->type, M_BLOOD_SCENT))
-            range++;
-    }
-
-    return (range);
-}
-
-//#define DEBUG_PATHFIND
-monster_pathfind::monster_pathfind()
-    : mons(), target(), range(0), min_length(0), max_length(0), dist(), prev()
-{
-}
-
-monster_pathfind::~monster_pathfind()
-{
-}
-
-void monster_pathfind::set_range(int r)
-{
-    if (r >= 0)
-        range = r;
-}
-
-coord_def monster_pathfind::next_pos(const coord_def &c) const
-{
-    return c + Compass[prev[c.x][c.y]];
-}
-
-// The main method in the monster_pathfind class.
-// Returns true if a path was found, else false.
-bool monster_pathfind::init_pathfind(const monsters *mon, coord_def dest,
-                                     bool diag, bool msg, bool pass_unmapped)
-{
-    mons   = mon;
-
-    // We're doing a reverse search from target to monster.
-    start  = dest;
-    target = mon->pos();
-    pos    = start;
-    allow_diagonals   = diag;
-    traverse_unmapped = pass_unmapped;
-
-    // Easy enough. :P
-    if (start == target)
-    {
-        if (msg)
-            mpr("The monster is already there!");
-
-        return (true);
-    }
-
-    return start_pathfind(msg);
-}
-
-bool monster_pathfind::init_pathfind(coord_def src, coord_def dest, bool diag,
-                                     bool msg)
-{
-    start  = src;
-    target = dest;
-    pos    = start;
-    allow_diagonals = diag;
-
-    // Easy enough. :P
-    if (start == target)
-        return (true);
-
-    return start_pathfind(msg);
-}
-
-bool monster_pathfind::start_pathfind(bool msg)
-{
-    // NOTE: We never do any traversable() check for the starting square
-    //       (target). This means that even if the target cannot be reached
-    //       we may still find a path leading adjacent to this position, which
-    //       is desirable if e.g. the player is hovering over deep water
-    //       surrounded by shallow water or floor, or if a foe is hiding in
-    //       a wall.
-    //       If the surrounding squares also are not traversable, we return
-    //       early that no path could be found.
-
-    max_length = min_length = grid_distance(pos.x, pos.y, target.x, target.y);
-    for (int i = 0; i < GXM; i++)
-        for (int j = 0; j < GYM; j++)
-            dist[i][j] = INFINITE_DISTANCE;
-
-    dist[pos.x][pos.y] = 0;
-
-    bool success = false;
-    do
-    {
-        // Calculate the distance to all neighbours of the current position,
-        // and add them to the hash, if they haven't already been looked at.
-        success = calc_path_to_neighbours();
-        if (success)
-            return (true);
-
-        // Pull the position with shortest distance estimate to our target grid.
-        success = get_best_position();
-
-        if (!success)
-        {
-            if (msg)
-            {
-                mprf("Couldn't find a path from (%d,%d) to (%d,%d).",
-                     target.x, target.y, start.x, start.y);
-            }
-            return (false);
-        }
-    }
-    while (true);
-}
-
-// Returns true as soon as we encounter the target.
-bool monster_pathfind::calc_path_to_neighbours()
-{
-    coord_def npos;
-    int distance, old_dist, total;
-
-    // For each point, we look at all neighbour points. Check the orthogonals
-    // last, so that, should an orthogonal and a diagonal direction have the
-    // same total travel cost, the orthogonal will be picked first, and thus
-    // zigzagging will be significantly reduced.
-    //
-    //      1  0  3       This means directions are looked at, in order,
-    //       \ | /        1, 3, 5, 7 (diagonals) followed by 0, 2, 4, 6
-    //      6--.--2       (orthogonals). This is achieved by the assignment
-    //       / | \        of (dir = 0) once dir has passed 7.
-    //      7  4  5
-    //
-    for (int dir = 1; dir < 8; (dir += 2) == 9 && (dir = 0))
-    {
-        // Skip diagonal movement.
-        if (!allow_diagonals && (dir % 2))
-            continue;
-
-        npos = pos + Compass[dir];
-
-#ifdef DEBUG_PATHFIND
-        mprf("Looking at neighbour (%d,%d)", npos.x, npos.y);
-#endif
-        if (!in_bounds(npos))
-            continue;
-
-        if (!traversable(npos))
-            continue;
-
-        // Ignore this grid if it takes us above the allowed distance.
-        if (range && estimated_cost(npos) > range)
-            continue;
-
-        distance = dist[pos.x][pos.y] + travel_cost(npos);
-        old_dist = dist[npos.x][npos.y];
-#ifdef DEBUG_PATHFIND
-        mprf("old dist: %d, new dist: %d, infinite: %d", old_dist, distance,
-             INFINITE_DISTANCE);
-#endif
-        // If the new distance is better than the old one (initialised with
-        // INFINITE), update the position.
-        if (distance < old_dist)
-        {
-            // Calculate new total path length.
-            total = distance + estimated_cost(npos);
-            if (old_dist == INFINITE_DISTANCE)
-            {
-#ifdef DEBUG_PATHFIND
-                mprf("Adding (%d,%d) to hash (total dist = %d)",
-                     npos.x, npos.y, total);
-#endif
-                add_new_pos(npos, total);
-                if (total > max_length)
-                    max_length = total;
-            }
-            else
-            {
-#ifdef DEBUG_PATHFIND
-                mprf("Improving (%d,%d) to total dist %d",
-                     npos.x, npos.y, total);
-#endif
-
-                update_pos(npos, total);
-            }
-
-            // Update distance start->pos.
-            dist[npos.x][npos.y] = distance;
-
-            // Set backtracking information.
-            // Converts the Compass direction to its counterpart.
-            //      0  1  2         4  5  6
-            //      7  .  3   ==>   3  .  7       e.g. (3 + 4) % 8          = 7
-            //      6  5  4         2  1  0            (7 + 4) % 8 = 11 % 8 = 3
-
-            prev[npos.x][npos.y] = (dir + 4) % 8;
-
-            // Are we finished?
-            if (npos == target)
-            {
-#ifdef DEBUG_PATHFIND
-                mpr("Arrived at target.");
-#endif
-                return (true);
-            }
-        }
-    }
-    return (false);
-}
-
-// Starting at known min_length (minimum total estimated path distance), check
-// the hash for existing vectors, then pick the last entry of the first vector
-// that matches. Update min_length, if necessary.
-bool monster_pathfind::get_best_position()
-{
-    for (int i = min_length; i <= max_length; i++)
-    {
-        if (!hash[i].empty())
-        {
-            if (i > min_length)
-                min_length = i;
-
-            std::vector<coord_def> &vec = hash[i];
-            // Pick the last position pushed into the vector as it's most
-            // likely to be close to the target.
-            pos = vec[vec.size()-1];
-            vec.pop_back();
-
-#ifdef DEBUG_PATHFIND
-            mprf("Returning (%d, %d) as best pos with total dist %d.",
-                 pos.x, pos.y, min_length);
-#endif
-
-            return (true);
-        }
-#ifdef DEBUG_PATHFIND
-        mprf("No positions for path length %d.", i);
-#endif
-    }
-
-    // Nothing found? Then there's no path! :(
-    return (false);
-}
-
-// Using the prev vector backtrack from start to target to find all steps to
-// take along the shortest path.
-std::vector<coord_def> monster_pathfind::backtrack()
-{
-#ifdef DEBUG_PATHFIND
-    mpr("Backtracking...");
-#endif
-    std::vector<coord_def> path;
-    pos = target;
-    path.push_back(pos);
-
-    if (pos == start)
-        return path;
-
-    int dir;
-    do
-    {
-        dir = prev[pos.x][pos.y];
-        pos = pos + Compass[dir];
-        ASSERT(in_bounds(pos));
-#ifdef DEBUG_PATHFIND
-        mprf("prev: (%d, %d), pos: (%d, %d)", Compass[dir].x, Compass[dir].y,
-                                              pos.x, pos.y);
-#endif
-        path.push_back(pos);
-
-        if (pos.x == 0 && pos.y == 0)
-            break;
-    }
-    while (pos != start);
-    ASSERT(pos == start);
-
-    return (path);
-}
-
-// Reduces the path coordinates to only a couple of key waypoints needed
-// to reach the target. Waypoints are chosen such that from one waypoint you
-// can see (and, more importantly, reach) the next one. Note that
-// can_go_straight() is probably rather too conservative in these estimates.
-// This is done because Crawl's pathfinding - once a target is in sight and easy
-// reach - is both very robust and natural, especially if we want to flexibly
-// avoid plants and other monsters in the way.
-std::vector<coord_def> monster_pathfind::calc_waypoints()
-{
-    std::vector<coord_def> path = backtrack();
-
-    // If no path found, nothing to be done.
-    if (path.empty())
-        return path;
-
-    dungeon_feature_type can_move;
-    if (mons_amphibious(mons))
-        can_move = DNGN_DEEP_WATER;
-    else
-        can_move = DNGN_SHALLOW_WATER;
-
-    std::vector<coord_def> waypoints;
-    pos = path[0];
-
-#ifdef DEBUG_PATHFIND
-    mpr(EOL "Waypoints:");
-#endif
-    for (unsigned int i = 1; i < path.size(); i++)
-    {
-        if (can_go_straight(pos, path[i], can_move))
-            continue;
-        else
-        {
-            pos = path[i-1];
-            waypoints.push_back(pos);
-#ifdef DEBUG_PATHFIND
-            mprf("waypoint: (%d, %d)", pos.x, pos.y);
-#endif
-        }
-    }
-
-    // Add the actual target to the list of waypoints, so we can later check
-    // whether a tracked enemy has moved too much, in case we have to update
-    // the path.
-    if (pos != path[path.size() - 1])
-        waypoints.push_back(path[path.size() - 1]);
-
-    return (waypoints);
-}
-
-bool monster_pathfind::traversable(const coord_def p)
-{
-    if (traverse_unmapped && grd(p) == DNGN_UNSEEN)
-        return (true);
-
-    if (mons)
-        return mons_traversable(p);
-
-    return (!feat_is_solid(grd(p)) && !feat_destroys_items(grd(p)));
-}
-
-// Checks whether a given monster can pass over a certain position, respecting
-// its preferred habit and capability of flight or opening doors.
-bool monster_pathfind::mons_traversable(const coord_def p)
-{
-    const monster_type montype = mons_is_zombified(mons) ? mons_zombie_base(mons)
-                                                         : mons->type;
-
-    if (!monster_habitable_grid(montype, grd(p)))
-        return (false);
-
-    // Monsters that can't open doors won't be able to pass them.
-    if (feat_is_closed_door(grd(p)) || grd(p) == DNGN_SECRET_DOOR)
-    {
-        if (mons_is_zombified(mons))
-        {
-            if (mons_class_itemuse(montype) < MONUSE_OPEN_DOORS)
-                return (false);
-        }
-        else if (mons_itemuse(mons) < MONUSE_OPEN_DOORS)
-            return (false);
-    }
-
-    // Your friends only know about doors you know about, unless they feel
-    // at home in this branch.
-    if (grd(p) == DNGN_SECRET_DOOR && mons->friendly()
-        && (mons_intel(mons) < I_NORMAL || !mons_is_native_in_branch(mons)))
-    {
-        return (false);
-    }
-
-    const trap_def* ptrap = find_trap(p);
-    if (ptrap)
-    {
-        const trap_type tt = ptrap->type;
-
-        // Don't allow allies to pass over known (to them) Zot traps.
-        if (tt == TRAP_ZOT
-            && ptrap->is_known(mons)
-            && mons->friendly())
-        {
-            return (false);
-        }
-
-        // Monsters cannot travel over teleport traps.
-        if (!_can_place_on_trap(montype, tt))
-            return (false);
-    }
-
-    return (true);
-}
-
-int monster_pathfind::travel_cost(coord_def npos)
-{
-    if (mons)
-        return mons_travel_cost(npos);
-
-    return (1);
-}
-
-// Assumes that grids that really cannot be entered don't even get here.
-// (Checked by traversable().)
-int monster_pathfind::mons_travel_cost(coord_def npos)
-{
-    ASSERT(grid_distance(pos, npos) <= 1);
-
-    // Doors need to be opened.
-    if (feat_is_closed_door(grd(npos)) || grd(npos) == DNGN_SECRET_DOOR)
-        return 2;
-
-    const int montype = mons_is_zombified(mons) ? mons_zombie_base(mons)
-                                                : mons->type;
-
-    const bool airborne = _mons_airborne(montype, -1, false);
-
-    // Travelling through water, entering or leaving water is more expensive
-    // for non-amphibious monsters, so they'll avoid it where possible.
-    // (The resulting path might not be optimal but it will lead to a path
-    // a monster of such habits is likely to prefer.)
-    // Only tested for shallow water since they can't enter deep water anyway.
-    if (!airborne && !mons_class_amphibious(montype)
-        && (grd(pos) == DNGN_SHALLOW_WATER || grd(npos) == DNGN_SHALLOW_WATER))
-    {
-        return 2;
-    }
-
-    // Try to avoid (known) traps.
-    const trap_def* ptrap = find_trap(npos);
-    if (ptrap)
-    {
-        const bool knows_trap = ptrap->is_known(mons);
-        const trap_type tt = ptrap->type;
-        if (tt == TRAP_ALARM || tt == TRAP_ZOT)
-        {
-            // Your allies take extra precautions to avoid known alarm traps.
-            // Zot traps are considered intraversable.
-            if (knows_trap && mons->friendly())
-                return (3);
-
-            // To hostile monsters, these traps are completely harmless.
-            return 1;
-        }
-
-        // Mechanical traps can be avoided by flying, as can shafts, and
-        // tele traps are never traversable anyway.
-        if (knows_trap && !airborne)
-            return 2;
-    }
-
-    return 1;
-}
-
-// The estimated cost to reach a grid is simply max(dx, dy).
-int monster_pathfind::estimated_cost(coord_def p)
-{
-    return (grid_distance(p, target));
-}
-
-void monster_pathfind::add_new_pos(coord_def npos, int total)
-{
-    hash[total].push_back(npos);
-}
-
-void monster_pathfind::update_pos(coord_def npos, int total)
-{
-    // Find hash position of old distance and delete it,
-    // then call_add_new_pos.
-    int old_total = dist[npos.x][npos.y] + estimated_cost(npos);
-
-    std::vector<coord_def> &vec = hash[old_total];
-    for (unsigned int i = 0; i < vec.size(); i++)
-    {
-        if (vec[i] == npos)
-        {
-            vec.erase(vec.begin() + i);
-            break;
-        }
-    }
-
-    add_new_pos(npos, total);
-}
-
-/////////////////////////////////////////////////////////////////////////////
 //
 // Random monsters for portal vaults.
 //