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0ad/source/simulation2/helpers/HierarchicalPathfinder.h

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/* Copyright (C) 2021 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. 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.
*
* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_HIERPATHFINDER
#define INCLUDED_HIERPATHFINDER
#include "Pathfinding.h"
#include "ps/CLogger.h"
#include "renderer/TerrainOverlay.h"
#include "Render.h"
#include "graphics/SColor.h"
#include <map>
#include <set>
/**
* Hierarchical pathfinder.
*
* Deals with connectivity (can point A reach point B?).
*
* The navcell-grid representation of the map is split into fixed-size chunks.
* Within a chunk, each maximal set of adjacently-connected passable navcells
* is defined as a region.
* Each region is a vertex in the hierarchical pathfinder's graph.
* When two regions in adjacent chunks are connected by passable navcells,
* the graph contains an edge between the corresponding two vertexes.
* By design, there can never be an edge between two regions in the same chunk.
*
* Those fixed-size chunks are used to efficiently compute "global regions" by effectively flood-filling.
* Those can then be used to immediately determine if two reachables points are connected.
*
* The main use of this class is to convert an arbitrary PathGoal to a reachable navcell.
* This happens in MakeGoalReachable.
*
*/
#ifdef TEST
class TestCmpPathfinder;
class TestHierarchicalPathfinder;
#endif
class HierarchicalOverlay;
class SceneCollector;
class HierarchicalPathfinder
{
#ifdef TEST
friend class TestCmpPathfinder;
friend class TestHierarchicalPathfinder;
#endif
public:
typedef u32 GlobalRegionID;
struct RegionID
{
u8 ci, cj; // chunk ID
u16 r; // unique-per-chunk local region ID
RegionID(u8 ci, u8 cj, u16 r) : ci(ci), cj(cj), r(r) { }
bool operator<(const RegionID& b) const
{
// Sort by chunk ID, then by per-chunk region ID
if (ci < b.ci)
return true;
if (b.ci < ci)
return false;
if (cj < b.cj)
return true;
if (b.cj < cj)
return false;
return r < b.r;
}
bool operator==(const RegionID& b) const
{
return ((ci == b.ci) && (cj == b.cj) && (r == b.r));
}
// Returns the distance from the center to the point (i, j)
inline u32 DistanceTo(u16 i, u16 j) const
{
return (ci * CHUNK_SIZE + CHUNK_SIZE/2 - i) * (ci * CHUNK_SIZE + CHUNK_SIZE/2 - i) +
(cj * CHUNK_SIZE + CHUNK_SIZE/2 - j) * (cj * CHUNK_SIZE + CHUNK_SIZE/2 - j);
}
};
HierarchicalPathfinder();
~HierarchicalPathfinder();
void SetDebugOverlay(bool enabled, const CSimContext* simContext);
// Non-pathfinding grids will never be recomputed on calling HierarchicalPathfinder::Update
void Recompute(Grid<NavcellData>* passabilityGrid,
const std::map<std::string, pass_class_t>& nonPathfindingPassClassMasks,
const std::map<std::string, pass_class_t>& pathfindingPassClassMasks);
void Update(Grid<NavcellData>* grid, const Grid<u8>& dirtinessGrid);
RegionID Get(u16 i, u16 j, pass_class_t passClass) const;
GlobalRegionID GetGlobalRegion(u16 i, u16 j, pass_class_t passClass) const;
GlobalRegionID GetGlobalRegion(RegionID region, pass_class_t passClass) const;
/**
* Updates @p goal so that it's guaranteed to be reachable from the navcell
* @p i0, @p j0 (which is assumed to be on a passable navcell).
*
* If the goal is not reachable, it is replaced with a point goal nearest to
* the goal center.
*
* In the case of a non-point reachable goal, it is replaced with a point goal
* at the reachable navcell of the goal which is nearest to the starting navcell.
*
* @returns true if the goal was reachable, false otherwise.
*/
bool MakeGoalReachable(u16 i0, u16 j0, PathGoal& goal, pass_class_t passClass) const;
/**
* @return true if the goal is reachable from navcell i0, j0.
* (similar to MakeGoalReachable but only checking for reachability).
*/
bool IsGoalReachable(u16 i0, u16 j0, const PathGoal& goal, pass_class_t passClass) const;
/**
* Updates @p i, @p j (which is assumed to be an impassable navcell)
* to the nearest passable navcell.
*/
void FindNearestPassableNavcell(u16& i, u16& j, pass_class_t passClass) const;
/**
* Generates the connectivity grid associated with the given pass_class
*/
Grid<u16> GetConnectivityGrid(pass_class_t passClass) const;
pass_class_t GetPassabilityClass(const std::string& name) const
{
auto it = m_PassClassMasks.find(name);
if (it != m_PassClassMasks.end())
return it->second;
LOGERROR("Invalid passability class name '%s'", name.c_str());
return 0;
}
void RenderSubmit(SceneCollector& collector);
private:
static const u8 CHUNK_SIZE = 96; // number of navcells per side
// TODO: figure out best number. Probably 64 < n < 128
struct Chunk
{
u8 m_ChunkI, m_ChunkJ; // chunk ID
std::vector<u16> m_RegionsID; // IDs of local regions, 0 (impassable) excluded
u16 m_Regions[CHUNK_SIZE][CHUNK_SIZE]; // local region ID per navcell
cassert(CHUNK_SIZE*CHUNK_SIZE/2 < 65536); // otherwise we could overflow m_RegionsID with a checkerboard pattern
void InitRegions(int ci, int cj, Grid<NavcellData>* grid, pass_class_t passClass);
RegionID Get(int i, int j) const;
void RegionCenter(u16 r, int& i, int& j) const;
void RegionNavcellNearest(u16 r, int iGoal, int jGoal, int& iBest, int& jBest, u32& dist2Best) const;
bool RegionNearestNavcellInGoal(u16 r, u16 i0, u16 j0, const PathGoal& goal, u16& iOut, u16& jOut, u32& dist2Best) const;
#ifdef TEST
bool operator==(const Chunk& b) const
{
return (m_ChunkI == b.m_ChunkI && m_ChunkJ == b.m_ChunkJ && m_RegionsID.size() == b.m_RegionsID.size() && memcmp(&m_Regions, &b.m_Regions, sizeof(u16) * CHUNK_SIZE * CHUNK_SIZE) == 0);
}
#endif
};
const Chunk& GetChunk(u8 ci, u8 cj, pass_class_t passClass) const
{
return m_Chunks.at(passClass).at(cj * m_ChunksW + ci);
}
typedef std::map<RegionID, std::set<RegionID> > EdgesMap;
void ComputeNeighbors(EdgesMap& edges, Chunk& a, Chunk& b, bool transpose, bool opposite) const;
void RecomputeAllEdges(pass_class_t passClass, EdgesMap& edges);
void UpdateEdges(u8 ci, u8 cj, pass_class_t passClass, EdgesMap& edges);
void UpdateGlobalRegions(const std::map<pass_class_t, std::vector<RegionID> >& needNewGlobalRegionMap);
/**
* Returns all reachable regions, optionally ordered in a specific manner.
*/
template<typename Ordering>
void FindReachableRegions(RegionID from, std::set<RegionID, Ordering>& reachable, pass_class_t passClass) const
{
// Flood-fill the region graph, starting at 'from',
// collecting all the regions that are reachable via edges
reachable.insert(from);
const EdgesMap& edgeMap = m_Edges.at(passClass);
if (edgeMap.find(from) == edgeMap.end())
return;
std::vector<RegionID> open;
open.reserve(64);
open.push_back(from);
while (!open.empty())
{
RegionID curr = open.back();
open.pop_back();
for (const RegionID& region : edgeMap.at(curr))
// Add to the reachable set; if this is the first time we added
// it then also add it to the open list
if (reachable.insert(region).second)
open.push_back(region);
}
}
struct SortByCenterToPoint
{
SortByCenterToPoint(u16 i, u16 j): gi(i), gj(j) {};
bool operator()(const HierarchicalPathfinder::RegionID& a, const HierarchicalPathfinder::RegionID& b) const
{
if (a.DistanceTo(gi, gj) < b.DistanceTo(gi, gj))
return true;
if (a.DistanceTo(gi, gj) > b.DistanceTo(gi, gj))
return false;
return a.r < b.r;
}
u16 gi, gj;
};
void FindNearestNavcellInRegions(const std::set<RegionID, SortByCenterToPoint>& regions,
u16& iGoal, u16& jGoal, pass_class_t passClass) const;
struct InterestingRegion {
RegionID region;
u16 bestI;
u16 bestJ;
};
struct SortByBestToPoint
{
SortByBestToPoint(u16 i, u16 j): gi(i), gj(j) {};
bool operator()(const InterestingRegion& a, const InterestingRegion& b) const
{
if ((a.bestI - gi) * (a.bestI - gi) + (a.bestJ - gj) * (a.bestJ - gj) < (b.bestI - gi) * (b.bestI - gi) + (b.bestJ - gj) * (b.bestJ - gj))
return true;
if ((a.bestI - gi) * (a.bestI - gi) + (a.bestJ - gj) * (a.bestJ - gj) > (b.bestI - gi) * (b.bestI - gi) + (b.bestJ - gj) * (b.bestJ - gj))
return false;
return a.region.r < b.region.r;
}
u16 gi, gj;
};
// Returns the region along with the best cell for optimisation.
void FindGoalRegionsAndBestNavcells(u16 i0, u16 j0, u16 gi, u16 gj, const PathGoal& goal, std::set<InterestingRegion, SortByBestToPoint>& regions, pass_class_t passClass) const;
void FillRegionOnGrid(const RegionID& region, pass_class_t passClass, u16 value, Grid<u16>& grid) const;
u16 m_W, m_H;
u8 m_ChunksW, m_ChunksH;
std::map<pass_class_t, std::vector<Chunk> > m_Chunks;
std::map<pass_class_t, EdgesMap> m_Edges;
std::map<pass_class_t, std::map<RegionID, GlobalRegionID> > m_GlobalRegions;
GlobalRegionID m_NextGlobalRegionID;
// Passability classes for which grids will be updated when calling Update
std::map<std::string, pass_class_t> m_PassClassMasks;
void AddDebugEdges(pass_class_t passClass);
HierarchicalOverlay* m_DebugOverlay;
const CSimContext* m_SimContext; // Used for drawing the debug lines
public:
std::vector<SOverlayLine> m_DebugOverlayLines;
};
class HierarchicalOverlay : public TerrainTextureOverlay
{
public:
HierarchicalPathfinder& m_PathfinderHier;
HierarchicalOverlay(HierarchicalPathfinder& pathfinderHier) :
TerrainTextureOverlay(Pathfinding::NAVCELLS_PER_TERRAIN_TILE), m_PathfinderHier(pathfinderHier)
{
}
virtual void BuildTextureRGBA(u8* data, size_t w, size_t h)
{
ENSURE(h <= std::numeric_limits<u16>::max() && w <= std::numeric_limits<u16>::max());
u16 height = static_cast<u16>(h);
u16 width = static_cast<u16>(w);
pass_class_t passClass = m_PathfinderHier.GetPassabilityClass("default");
for (u16 j = 0; j < height; ++j)
{
for (u16 i = 0; i < width; ++i)
{
SColor4ub color;
HierarchicalPathfinder::RegionID rid = m_PathfinderHier.Get(i, j, passClass);
if (rid.r == 0)
color = SColor4ub(0, 0, 0, 0);
else if (rid.r == 0xFFFF)
color = SColor4ub(255, 0, 255, 255);
else
color = GetColor(rid.r + rid.ci*5 + rid.cj*7, 127);
*data++ = color.R;
*data++ = color.G;
*data++ = color.B;
*data++ = color.A;
}
}
}
};
#endif // INCLUDED_HIERPATHFINDER