Update: Translations from eints

[openttd-github.git] / src / pathfinder / water_regions.cpp

/*
 * This file is part of OpenTTD.
 * OpenTTD 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 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

 /** @file water_regions.cpp Handles dividing the water in the map into square regions to assist pathfinding. */

#include "stdafx.h"
#include "map_func.h"
#include "water_regions.h"
#include "map_func.h"
#include "tilearea_type.h"
#include "track_func.h"
#include "transport_type.h"
#include "landscape.h"
#include "tunnelbridge_map.h"
#include "follow_track.hpp"
#include "ship.h"
#include "debug.h"

using TWaterRegionTraversabilityBits = uint16_t;
constexpr TWaterRegionPatchLabel FIRST_REGION_LABEL = 1;

static_assert(sizeof(TWaterRegionTraversabilityBits) * 8 == WATER_REGION_EDGE_LENGTH);
static_assert(sizeof(TWaterRegionPatchLabel) == sizeof(uint8_t)); // Important for the hash calculation.

static inline TrackBits GetWaterTracks(TileIndex tile) { return TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_WATER, 0)); }
static inline bool IsAqueductTile(TileIndex tile) { return IsBridgeTile(tile) && GetTunnelBridgeTransportType(tile) == TRANSPORT_WATER; }

static inline int GetWaterRegionX(TileIndex tile) { return TileX(tile) / WATER_REGION_EDGE_LENGTH; }
static inline int GetWaterRegionY(TileIndex tile) { return TileY(tile) / WATER_REGION_EDGE_LENGTH; }

static inline int GetWaterRegionMapSizeX() { return Map::SizeX() / WATER_REGION_EDGE_LENGTH; }
static inline int GetWaterRegionMapSizeY() { return Map::SizeY() / WATER_REGION_EDGE_LENGTH; }

static inline TWaterRegionIndex GetWaterRegionIndex(int region_x, int region_y) { return GetWaterRegionMapSizeX() * region_y + region_x; }
static inline TWaterRegionIndex GetWaterRegionIndex(TileIndex tile) { return GetWaterRegionIndex(GetWaterRegionX(tile), GetWaterRegionY(tile)); }

using TWaterRegionPatchLabelArray = std::array<TWaterRegionPatchLabel, WATER_REGION_NUMBER_OF_TILES>;

/**
 * The data stored for each water region.
 */
class WaterRegionData {
        friend class WaterRegion;

        std::array<TWaterRegionTraversabilityBits, DIAGDIR_END> edge_traversability_bits{};
        std::unique_ptr<TWaterRegionPatchLabelArray> tile_patch_labels; // Tile patch labels, this may be nullptr in the following trivial cases: region is invalid, region is only land (0 patches), region is only water (1 patch)
        bool has_cross_region_aqueducts = false;
        TWaterRegionPatchLabel number_of_patches = 0; // 0 = no water, 1 = one single patch of water, etc...
};

/**
 * Represents a square section of the map of a fixed size. Within this square individual unconnected patches of water are
 * identified using a Connected Component Labeling (CCL) algorithm. Note that all information stored in this class applies
 * only to tiles within the square section, there is no knowledge about the rest of the map. This makes it easy to invalidate
 * and update a water region if any changes are made to it, such as construction or terraforming.
 */
class WaterRegion
{
private:
        WaterRegionData &data;
        const OrthogonalTileArea tile_area;

        /**
         * Returns the local index of the tile within the region. The N corner represents 0,
         * the x direction is positive in the SW direction, and Y is positive in the SE direction.
         * @param tile Tile within the water region.
         * @returns The local index.
         */
        inline int GetLocalIndex(TileIndex tile) const
        {
                assert(this->tile_area.Contains(tile));
                return (TileX(tile) - TileX(this->tile_area.tile)) + WATER_REGION_EDGE_LENGTH * (TileY(tile) - TileY(this->tile_area.tile));
        }

public:
        WaterRegion(int region_x, int region_y, WaterRegionData &water_region_data)
                : data(water_region_data)
                , tile_area(TileXY(region_x * WATER_REGION_EDGE_LENGTH, region_y * WATER_REGION_EDGE_LENGTH), WATER_REGION_EDGE_LENGTH, WATER_REGION_EDGE_LENGTH)
        {}

        OrthogonalTileIterator begin() const { return this->tile_area.begin(); }
        OrthogonalTileIterator end() const { return this->tile_area.end(); }

        /**
         * Returns a set of bits indicating whether an edge tile on a particular side is traversable or not. These
         * values can be used to determine whether a ship can enter/leave the region through a particular edge tile.
         * @see GetLocalIndex() for a description of the coordinate system used.
         * @param side Which side of the region we want to know the edge traversability of.
         * @returns A value holding the edge traversability bits.
         */
        TWaterRegionTraversabilityBits GetEdgeTraversabilityBits(DiagDirection side) const { return this->data.edge_traversability_bits[side]; }

        /**
         * @returns The amount of individual water patches present within the water region. A value of
         * 0 means there is no water present in the water region at all.
         */
        int NumberOfPatches() const { return static_cast<int>(this->data.number_of_patches); }

        /**
         * @returns Whether the water region contains aqueducts that cross the region boundaries.
         */
        bool HasCrossRegionAqueducts() const { return this->data.has_cross_region_aqueducts; }

        /**
         * Returns the patch label that was assigned to the tile.
         * @param tile The tile of which we want to retrieve the label.
         * @returns The label assigned to the tile.
         */
        TWaterRegionPatchLabel GetLabel(TileIndex tile) const
        {
                assert(this->tile_area.Contains(tile));
                if (this->data.tile_patch_labels == nullptr) {
                        return this->NumberOfPatches() == 0 ? INVALID_WATER_REGION_PATCH : FIRST_REGION_LABEL;
                }
                return (*this->data.tile_patch_labels)[this->GetLocalIndex(tile)];
        }

        /**
         * Performs the connected component labeling and other data gathering.
         * @see WaterRegion
         */
        void ForceUpdate()
        {
                Debug(map, 3, "Updating water region ({},{})", GetWaterRegionX(this->tile_area.tile), GetWaterRegionY(this->tile_area.tile));
                this->data.has_cross_region_aqueducts = false;

                /* Acquire a tile patch label array if this region does not already have one */
                if (this->data.tile_patch_labels == nullptr) {
                        this->data.tile_patch_labels = std::make_unique<TWaterRegionPatchLabelArray>();
                }

                this->data.tile_patch_labels->fill(INVALID_WATER_REGION_PATCH);
                this->data.edge_traversability_bits.fill(0);

                TWaterRegionPatchLabel current_label = FIRST_REGION_LABEL;
                TWaterRegionPatchLabel highest_assigned_label = INVALID_WATER_REGION_PATCH;

                /* Perform connected component labeling. This uses a flooding algorithm that expands until no
                 * additional tiles can be added. Only tiles inside the water region are considered. */
                for (const TileIndex start_tile : this->tile_area) {
                        static std::vector<TileIndex> tiles_to_check;
                        tiles_to_check.clear();
                        tiles_to_check.push_back(start_tile);

                        bool increase_label = false;
                        while (!tiles_to_check.empty()) {
                                const TileIndex tile = tiles_to_check.back();
                                tiles_to_check.pop_back();

                                const TrackdirBits valid_dirs = TrackBitsToTrackdirBits(GetWaterTracks(tile));
                                if (valid_dirs == TRACKDIR_BIT_NONE) continue;

                                TWaterRegionPatchLabel &tile_patch = (*this->data.tile_patch_labels)[this->GetLocalIndex(tile)];
                                if (tile_patch != INVALID_WATER_REGION_PATCH) continue;

                                tile_patch = current_label;
                                highest_assigned_label = current_label;
                                increase_label = true;

                                for (const Trackdir dir : SetTrackdirBitIterator(valid_dirs)) {
                                        /* By using a TrackFollower we "play by the same rules" as the actual ship pathfinder */
                                        CFollowTrackWater ft;
                                        if (ft.Follow(tile, dir)) {
                                                if (this->tile_area.Contains(ft.new_tile)) {
                                                        tiles_to_check.push_back(ft.new_tile);
                                                } else if (!ft.is_bridge) {
                                                        assert(DistanceManhattan(ft.new_tile, tile) == 1);
                                                        const auto side = DiagdirBetweenTiles(tile, ft.new_tile);
                                                        const int local_x_or_y = DiagDirToAxis(side) == AXIS_X ? TileY(tile) - TileY(this->tile_area.tile) : TileX(tile) - TileX(this->tile_area.tile);
                                                        SetBit(this->data.edge_traversability_bits[side], local_x_or_y);
                                                } else {
                                                        this->data.has_cross_region_aqueducts = true;
                                                }
                                        }
                                }
                        }

                        if (increase_label) current_label++;
                }

                this->data.number_of_patches = highest_assigned_label;

                if (this->NumberOfPatches() == 0 || (this->NumberOfPatches() == 1 &&
                                std::all_of(this->data.tile_patch_labels->begin(), this->data.tile_patch_labels->end(), [](TWaterRegionPatchLabel label) { return label == FIRST_REGION_LABEL; }))) {
                        /* No need for patch storage: trivial cases */
                        this->data.tile_patch_labels.reset();
                }
        }

        void PrintDebugInfo()
        {
                Debug(map, 9, "Water region {},{} labels and edge traversability = ...", GetWaterRegionX(this->tile_area.tile), GetWaterRegionY(this->tile_area.tile));

                const size_t max_element_width = std::to_string(this->NumberOfPatches()).size();

                std::string traversability = fmt::format("{:0{}b}", this->GetEdgeTraversabilityBits(DIAGDIR_NW), WATER_REGION_EDGE_LENGTH);
                Debug(map, 9, "    {:{}}", fmt::join(traversability, " "), max_element_width);
                Debug(map, 9, "  +{:->{}}+", "", WATER_REGION_EDGE_LENGTH * (max_element_width + 1) + 1);

                for (int y = 0; y < WATER_REGION_EDGE_LENGTH; ++y) {
                        std::string line{};
                        for (int x = 0; x < WATER_REGION_EDGE_LENGTH; ++x) {
                                const auto label = this->GetLabel(TileAddXY(this->tile_area.tile, x, y));
                                const std::string label_str = label == INVALID_WATER_REGION_PATCH ? "." : std::to_string(label);
                                line = fmt::format("{:{}}", label_str, max_element_width) + " " + line;
                        }
                        Debug(map, 9, "{} | {}| {}", GB(this->GetEdgeTraversabilityBits(DIAGDIR_SW), y, 1), line, GB(this->GetEdgeTraversabilityBits(DIAGDIR_NE), y, 1));
                }

                Debug(map, 9, "  +{:->{}}+", "", WATER_REGION_EDGE_LENGTH * (max_element_width + 1) + 1);
                traversability = fmt::format("{:0{}b}", this->GetEdgeTraversabilityBits(DIAGDIR_SE), WATER_REGION_EDGE_LENGTH);
                Debug(map, 9, "    {:{}}", fmt::join(traversability, " "), max_element_width);
        }
};

std::vector<WaterRegionData> _water_region_data;
std::vector<bool> _is_water_region_valid;

static TileIndex GetTileIndexFromLocalCoordinate(int region_x, int region_y, int local_x, int local_y)
{
        assert(local_x >= 0 && local_x < WATER_REGION_EDGE_LENGTH);
        assert(local_y >= 0 && local_y < WATER_REGION_EDGE_LENGTH);
        return TileXY(WATER_REGION_EDGE_LENGTH * region_x + local_x, WATER_REGION_EDGE_LENGTH * region_y + local_y);
}

static TileIndex GetEdgeTileCoordinate(int region_x, int region_y, DiagDirection side, int x_or_y)
{
        assert(x_or_y >= 0 && x_or_y < WATER_REGION_EDGE_LENGTH);
        switch (side) {
                case DIAGDIR_NE: return GetTileIndexFromLocalCoordinate(region_x, region_y, 0, x_or_y);
                case DIAGDIR_SW: return GetTileIndexFromLocalCoordinate(region_x, region_y, WATER_REGION_EDGE_LENGTH - 1, x_or_y);
                case DIAGDIR_NW: return GetTileIndexFromLocalCoordinate(region_x, region_y, x_or_y, 0);
                case DIAGDIR_SE: return GetTileIndexFromLocalCoordinate(region_x, region_y, x_or_y, WATER_REGION_EDGE_LENGTH - 1);
                default: NOT_REACHED();
        }
}

static WaterRegion GetUpdatedWaterRegion(uint16_t region_x, uint16_t region_y)
{
        const TWaterRegionIndex index = GetWaterRegionIndex(region_x, region_y);
        WaterRegion water_region(region_x, region_y, _water_region_data[index]);
        if (!_is_water_region_valid[index]) {
                water_region.ForceUpdate();
                _is_water_region_valid[index] = true;
        }
        return water_region;
}

static WaterRegion GetUpdatedWaterRegion(TileIndex tile)
{
        return GetUpdatedWaterRegion(GetWaterRegionX(tile), GetWaterRegionY(tile));
}

/**
 * Returns the index of the water region.
 * @param water_region The water region to return the index for.
 */
static TWaterRegionIndex GetWaterRegionIndex(const WaterRegionDesc &water_region)
{
        return GetWaterRegionIndex(water_region.x, water_region.y);
}

/**
 * Calculates a number that uniquely identifies the provided water region patch.
 * @param water_region_patch The Water region to calculate the hash for.
 */
int CalculateWaterRegionPatchHash(const WaterRegionPatchDesc &water_region_patch)
{
        return water_region_patch.label | GetWaterRegionIndex(water_region_patch) << 8;
}

/**
 * Returns the center tile of a particular water region.
 * @param water_region The water region to find the center tile for.
 * @returns The center tile of the water region.
 */
TileIndex GetWaterRegionCenterTile(const WaterRegionDesc &water_region)
{
        return TileXY(water_region.x * WATER_REGION_EDGE_LENGTH + (WATER_REGION_EDGE_LENGTH / 2), water_region.y * WATER_REGION_EDGE_LENGTH + (WATER_REGION_EDGE_LENGTH / 2));
}

/**
 * Returns basic water region information for the provided tile.
 * @param tile The tile for which the information will be calculated.
 */
WaterRegionDesc GetWaterRegionInfo(TileIndex tile)
{
        return WaterRegionDesc{ GetWaterRegionX(tile), GetWaterRegionY(tile) };
}

/**
 * Returns basic water region patch information for the provided tile.
 * @param tile The tile for which the information will be calculated.
 */
WaterRegionPatchDesc GetWaterRegionPatchInfo(TileIndex tile)
{
        const WaterRegion region = GetUpdatedWaterRegion(tile);
        return WaterRegionPatchDesc{ GetWaterRegionX(tile), GetWaterRegionY(tile), region.GetLabel(tile) };
}

/**
 * Marks the water region that tile is part of as invalid.
 * @param tile Tile within the water region that we wish to invalidate.
 */
void InvalidateWaterRegion(TileIndex tile)
{
        if (!IsValidTile(tile)) return;

        auto invalidate_region = [](TileIndex tile) {
                const TWaterRegionIndex water_region_index = GetWaterRegionIndex(tile);
                if (!_is_water_region_valid[water_region_index]) Debug(map, 3, "Invalidated water region ({},{})", GetWaterRegionX(tile), GetWaterRegionY(tile));
                _is_water_region_valid[water_region_index] = false;
        };

        invalidate_region(tile);

        /* When updating the water region we look into the first tile of adjacent water regions to determine edge
         * traversability. This means that if we invalidate any region edge tiles we might also change the traversability
         * of the adjacent region. This code ensures the adjacent regions also get invalidated in such a case. */
        for (DiagDirection side = DIAGDIR_BEGIN; side < DIAGDIR_END; side++) {
                const TileIndex adjacent_tile = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(side));
                if (adjacent_tile == INVALID_TILE) continue;
                if (GetWaterRegionIndex(adjacent_tile) != GetWaterRegionIndex(tile)) invalidate_region(adjacent_tile);
        }
}

/**
 * Calls the provided callback function for all water region patches
 * accessible from one particular side of the starting patch.
 * @param water_region_patch Water patch within the water region to start searching from
 * @param side Side of the water region to look for neigboring patches of water
 * @param callback The function that will be called for each neighbor that is found
 */
static inline void VisitAdjacentWaterRegionPatchNeighbors(const WaterRegionPatchDesc &water_region_patch, DiagDirection side, TVisitWaterRegionPatchCallBack &func)
{
        if (water_region_patch.label == INVALID_WATER_REGION_PATCH) return;

        const WaterRegion current_region = GetUpdatedWaterRegion(water_region_patch.x, water_region_patch.y);

        const TileIndexDiffC offset = TileIndexDiffCByDiagDir(side);
        const int nx = water_region_patch.x + offset.x;
        const int ny = water_region_patch.y + offset.y;

        if (nx < 0 || ny < 0 || nx >= GetWaterRegionMapSizeX() || ny >= GetWaterRegionMapSizeY()) return;

        const WaterRegion neighboring_region = GetUpdatedWaterRegion(nx, ny);
        const DiagDirection opposite_side = ReverseDiagDir(side);

        /* Indicates via which local x or y coordinates (depends on the "side" parameter) we can cross over into the adjacent region. */
        const TWaterRegionTraversabilityBits traversability_bits = current_region.GetEdgeTraversabilityBits(side)
                & neighboring_region.GetEdgeTraversabilityBits(opposite_side);
        if (traversability_bits == 0) return;

        if (current_region.NumberOfPatches() == 1 && neighboring_region.NumberOfPatches() == 1) {
                func(WaterRegionPatchDesc{ nx, ny, FIRST_REGION_LABEL }); // No further checks needed because we know there is just one patch for both adjacent regions
                return;
        }

        /* Multiple water patches can be reached from the current patch. Check each edge tile individually. */
        static std::vector<TWaterRegionPatchLabel> unique_labels; // static and vector-instead-of-map for performance reasons
        unique_labels.clear();
        for (int x_or_y = 0; x_or_y < WATER_REGION_EDGE_LENGTH; ++x_or_y) {
                if (!HasBit(traversability_bits, x_or_y)) continue;

                const TileIndex current_edge_tile = GetEdgeTileCoordinate(water_region_patch.x, water_region_patch.y, side, x_or_y);
                const TWaterRegionPatchLabel current_label = current_region.GetLabel(current_edge_tile);
                if (current_label != water_region_patch.label) continue;

                const TileIndex neighbor_edge_tile = GetEdgeTileCoordinate(nx, ny, opposite_side, x_or_y);
                const TWaterRegionPatchLabel neighbor_label = neighboring_region.GetLabel(neighbor_edge_tile);
                assert(neighbor_label != INVALID_WATER_REGION_PATCH);
                if (std::find(unique_labels.begin(), unique_labels.end(), neighbor_label) == unique_labels.end()) unique_labels.push_back(neighbor_label);
        }
        for (TWaterRegionPatchLabel unique_label : unique_labels) func(WaterRegionPatchDesc{ nx, ny, unique_label });
}

/**
 * Calls the provided callback function on all accessible water region patches in
 * each cardinal direction, plus any others that are reachable via aqueducts.
 * @param water_region_patch Water patch within the water region to start searching from
 * @param callback The function that will be called for each accessible water patch that is found
 */
void VisitWaterRegionPatchNeighbors(const WaterRegionPatchDesc &water_region_patch, TVisitWaterRegionPatchCallBack &callback)
{
        if (water_region_patch.label == INVALID_WATER_REGION_PATCH) return;

        const WaterRegion current_region = GetUpdatedWaterRegion(water_region_patch.x, water_region_patch.y);

        /* Visit adjacent water region patches in each cardinal direction */
        for (DiagDirection side = DIAGDIR_BEGIN; side < DIAGDIR_END; side++) VisitAdjacentWaterRegionPatchNeighbors(water_region_patch, side, callback);

        /* Visit neigboring water patches accessible via cross-region aqueducts */
        if (current_region.HasCrossRegionAqueducts()) {
                for (const TileIndex tile : current_region) {
                        if (GetWaterRegionPatchInfo(tile) == water_region_patch && IsAqueductTile(tile)) {
                                const TileIndex other_end_tile = GetOtherBridgeEnd(tile);
                                if (GetWaterRegionIndex(tile) != GetWaterRegionIndex(other_end_tile)) callback(GetWaterRegionPatchInfo(other_end_tile));
                        }
                }
        }
}

/**
 * Allocates the appropriate amount of water regions for the current map size
 */
void AllocateWaterRegions()
{
        const int number_of_regions = GetWaterRegionMapSizeX() * GetWaterRegionMapSizeY();

        _water_region_data.clear();
        _water_region_data.resize(number_of_regions);

        _is_water_region_valid.clear();
        _is_water_region_valid.resize(number_of_regions, false);

        Debug(map, 2, "Allocating {} x {} water regions", GetWaterRegionMapSizeX(), GetWaterRegionMapSizeY());
        assert(_is_water_region_valid.size() == _water_region_data.size());
}

void PrintWaterRegionDebugInfo(TileIndex tile)
{
        GetUpdatedWaterRegion(tile).PrintDebugInfo();
}