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Slight improvement of the flood filling algorithm in the hierarchical pathfinder.

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Remove some useless check and a useless reverse loop, and add a flag to
prevent redundant checks.

Patch by fsincos, refs #3588

This was SVN commit r18011.
This commit is contained in:
Nicolas Auvray 2016-04-09 19:47:09 +00:00
parent cc35f221c8
commit 8c436a8a41
1 changed files with 12 additions and 10 deletions
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22
source/simulation2/helpers/HierarchicalPathfinder.cpp
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@ -1,4 +1,4 @@
/* Copyright (C) 2015 Wildfire Games.
/* Copyright (C) 2016 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
@ -25,14 +25,8 @@
// Find the root ID of a region, used by InitRegions
inline u16 RootID(u16 x, const std::vector<u16>& v)
{
// Just add a basic check for infinite loops
int checkLoop = 0;
while (v[x] < x)
{
++checkLoop;
ENSURE(checkLoop < 1000 && "Long loop (probably infinite), unable to find an invariant point");
x = v[x];
}
return x;
}
@ -58,6 +52,7 @@ void HierarchicalPathfinder::Chunk::InitRegions(int ci, int cj, Grid<NavcellData
u16* pCurrentID = NULL;
u16 LeftID = 0;
u16 DownID = 0;
bool Checked = false; // prevent some unneccessary RootID calls
connect.reserve(32); // TODO: What's a sensible number?
connect.push_back(0); // connect[0] = 0
@ -86,36 +81,43 @@ void HierarchicalPathfinder::Chunk::InitRegions(int ci, int cj, Grid<NavcellData
if (LeftID > 0)
{
*pCurrentID = LeftID;
if (*pCurrentID != DownID && DownID > 0)
if (*pCurrentID != DownID && DownID > 0 && !Checked)
{
u16 id0 = RootID(DownID, connect);
u16 id1 = RootID(LeftID, connect);
Checked = true; // this avoids repeatedly connecting the same IDs
if (id0 < id1)
connect[id1] = id0;
else if (id0 > id1)
connect[id0] = id1;
}
else if (DownID == 0)
Checked = false;
}
else if (DownID > 0)
{
*pCurrentID = DownID;
Checked = false;
}
else
{
// New ID
*pCurrentID = ++regionID;
connect.push_back(regionID);
Checked = false;
}
}
}
// Directly point the root ID
m_NumRegions = 0;
for (u16 i = regionID; i > 0; --i)
for (u16 i = 1; i <= regionID; ++i)
{
if (connect[i] == i)
++m_NumRegions;
else
connect[i] = RootID(i,connect);
connect[i] = RootID(i, connect);
}
// Replace IDs by the root ID