/* 参考 ：http://www.cnblogs.com/wantnon/p/4947067.html
* http://fab.cba.mit.edu/classes/S62.12/docs/Meijster_distance.pdf
* 具体算法名：Saito算法
* 因为初始化值都是未知的，通过一个大约估计的初始化，来重复来回算一个大致准确的距离
* 值 ？
*/
public void generateDistanceField(OpenHeightfield field)
{
if (field == null)
{
Logger.LogError("[OpenHeightfieldBuilder][generateNeighborLinks]field Empty");
return;
}
/*
* 先将OpenHeightField的Span数据转换成0和1的二值图。如果是边缘Span
* 那么就是0，否则就是NEEDS_INIT。
*/
OpenHeightfield.OpenHeightFieldIterator iter = field.GetEnumerator();
while( iter.MoveNext() )
{
OpenHeightSpan span = iter.Current;
bool isBorder = false;
for(int dir = 0; dir < 4; ++dir)
{
OpenHeightSpan nSpan = span.getNeighbor(dir);
if( null == nSpan
|| nSpan.getNeighbor(dir == 3 ? 0 : dir + 1) == null)
{
//如果8个邻居有任何一个缺失的话，那么就是边界Border
isBorder = true;
break;
}
}
if( isBorder )
{
//自己就是边界Border
span.setDistanceToBorder(BORDER);
}
else
{
//需要再次计算
span.setDistanceToBorder(NEEDS_INIT);
}
} //while
/*
* 逆时针访问？
*
* (-1,1) (0,1) (1,1)
* (-1,0) x (1,0)
* (-1,-1) (0,-1) (1,-1)
*/
//Pass 1
//顺序访问 (-1,0) (-1,-1) (0,-1) (1,-1)
iter.Reset();
while( iter.MoveNext() )
{
OpenHeightSpan span = iter.Current;
int selfDist = span.distanceToBorder();
if( selfDist == BORDER)
{
continue;
}
//(-1,0)
OpenHeightSpan nSpan = span.getNeighbor(0);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, true);
//(-1,-1),左下角的领域
nSpan = nSpan.getNeighbor(3); //领域0的领域3，也就是原Span的左下角
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, false);
//(0,-1)
nSpan = span.getNeighbor(3);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, true);
//(1,-1)
nSpan = nSpan.getNeighbor(2);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, true);
span.setDistanceToBorder(selfDist);
} // while
//Pass 2
//顺序访问 (1,0) (1,1) (0,1) (-1,1)
//注意这个是反向遍历
iter.ReverseReset();
while( iter.MoveNext() )
{
OpenHeightSpan span = iter.Current;
int selfDist = span.distanceToBorder();
if( selfDist == BORDER )
{
continue;
}
/*
* 因为经过Pass1之后 ，所有的Span要么就是Border
* 要么就是有个大概值的，不会等于NEED_INIT的。
* 所以直接按照按照上面的流程跑
*/
//(1,0)
OpenHeightSpan nSpan = span.getNeighbor(2);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, true);
//(1,1)
nSpan = nSpan.getNeighbor(1);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, false);
//(0,1)
nSpan = span.getNeighbor(1);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, true);
//(-1,1)
nSpan = nSpan.getNeighbor(0);
selfDist = calcMiniDistanceToBorder(selfDist, nSpan, false);
span.setDistanceToBorder(selfDist);
}
field.clearBorderDistanceBounds();
}
public void generateRegions( OpenHeightfield field )
{
if (null == field)
{
return;
}
//这个距离，控制生成的网络有多贴近实际的模型
int minDist = mTraversableAreaBorderSize + field.minBorderDistance();
int expandIterations = 4 + (mTraversableAreaBorderSize * 2); //TODO emmm
//排除奇数
int dist = (field.maxBorderDistance() - 1) & ~1 ;
List<OpenHeightSpan> floodedSpans = new List<OpenHeightSpan>(1024);
Stack<OpenHeightSpan> workingStack = new Stack<OpenHeightSpan>(1024);
OpenHeightfield.OpenHeightFieldIterator iter = field.GetEnumerator();
int nextRegionID = 1;
//高于这个距离的体素都得生成Regions，那剩下的体素怎么办呢？
while ( dist > minDist )
{
iter.Reset();
floodedSpans.Clear();
while( iter.MoveNext() )
{
OpenHeightSpan span = iter.Current;
if( span.regionID() == NULL_REGION
&& span.distanceToBorder() >= dist )
{
floodedSpans.Add(span);
}
}
if( nextRegionID > 1 )
{
//大于1表示已经至少存在1个region，先去尝试一下合并
if( dist > 0 )
{
expandRegions(floodedSpans, expandIterations);
}
else //这里不太可能会走到吧？除非minDist == 0
{
expandRegions(floodedSpans, -1);
}
}
//剩下的可能要生成新的Region
foreach( OpenHeightSpan span in floodedSpans )
{
if( null == span
|| span.regionID() != NULL_REGION )
{
continue;
}
//TODO ????
int fillTo = Math.Max(dist - 2, minDist);
if( floodNewRegion(span,fillTo,nextRegionID,workingStack ))
{
nextRegionID++;
}
}
//更新深度
dist = Math.Max(dist - 2, 0);
} //while dist > minDist
//最后一篇循环
iter.Reset();
floodedSpans.Clear();
while( iter.MoveNext() )
{
OpenHeightSpan span = iter.Current;
if( span.distanceToBorder() >= minDist
&& span.regionID() == NULL_REGION )
{
floodedSpans.Add(span);
}
}
if( minDist > 0 )
{
expandRegions(floodedSpans, expandIterations * 8);
}
else
{
expandRegions(floodedSpans, -1);
}
field.setRegionCount(nextRegionID);
//后处理
foreach( IOpenHeightFieldAlgorithm algorithm in mRegionAlgorithms )
{
algorithm.apply(field);
}
}
public void apply(OpenHeightfield field)
{
if (null == field)
{
Logger.LogError("[FilterOutSmallRegions][apply]field null");
return;
}
if (field.regionCount() < 2)
{
Logger.LogError("[FilterOutSmallRegions][apply]RegionCnt|{0}", field.regionCount());
return;
}
//PS：索引即是对应的ID
Region[] regions = new Region[field.regionCount()];
for (int i = 0; i < field.regionCount(); ++i)
{
regions[i] = new Region(i);
}
#region 收集邻接信息
OpenHeightfield.OpenHeightFieldIterator iter = field.GetEnumerator();
while (iter.MoveNext())
{
OpenHeightSpan span = iter.Current;
if (span.regionID() <= NULL_REGION)
{
continue;
}
//索引即RegionID
Region region = regions[span.regionID()];
region.spanCount++;
for (OpenHeightSpan nextHigherSpan = span.next();
nextHigherSpan != null;
nextHigherSpan = nextHigherSpan.next()
)
{
int nextHigherSpanRegionID = nextHigherSpan.regionID();
if (nextHigherSpanRegionID <= NULL_REGION)
{
continue;
}
//因为是同属一个Grid的，所以肯定是重叠的
if (!region.overlappingRegions.Contains(nextHigherSpanRegionID))
{
region.overlappingRegions.Add(nextHigherSpanRegionID);
}
} //for
if (region.connections.Count > 0)
{
continue;
}
int edgeDirection = getRegionEdgeDirection(span);
if (edgeDirection != -1)
{
findRegionConnections(span, edgeDirection, ref region.connections);
}
} // while
#endregion
#region 清理孤岛Region
for (int regionID = 1; regionID < field.regionCount(); ++regionID)
{
Region region = regions[regionID];
if (0 == region.spanCount)
{
continue;
}
// 有且仅有一个 Null Region 邻居
if (region.connections.Count == 1 &&
region.connections[0] == NULL_REGION)
{
if (region.spanCount < mMinUnconnectedRegionSize)
{
region.resetWithID(0);
}
}
} //for
#endregion
#region 合并小的Region
int mergeCount;
do
{
mergeCount = 0;
foreach (Region region in regions)
{
if (region.id <= NULL_REGION ||
region.spanCount == 0)
{
continue;
}
if (region.spanCount > mMergeRegionSize)
{
continue;
}
Region targetMergeRegion = null;
int smallestSizeFound = int.MaxValue;
foreach (int nRegionID in region.connections)
{
if (nRegionID <= 0)
{
continue;
}
Region nRegion = regions[nRegionID];
if (nRegion.spanCount < smallestSizeFound &&
canMerge(region, nRegion))
{
targetMergeRegion = nRegion;
smallestSizeFound = nRegion.spanCount;
}
} // foreach nRegionID
if (targetMergeRegion != null &&
mergeRegions(targetMergeRegion, region)) //为啥是反过来Merge。。。
{
int oldRegionID = region.id;
region.resetWithID(targetMergeRegion.id);
foreach (Region r in regions)
{
if (r.id <= NULL_REGION)
{
continue;
}
if (r.id == oldRegionID)
{
r.id = targetMergeRegion.id;
}
else
{
replaceNeighborRegionID(r, oldRegionID, targetMergeRegion.id);
}
} // foreach regions
mergeCount++;
} // if mergerRegion
} // foreach region
} while (mergeCount > 0);
#endregion
#region re-map 区域ID，保持ID连接
foreach (Region region in regions)
{
if (region.id >= NULL_REGION)
{
region.remap = true;
}
}
int currRegionID = NULL_REGION;
foreach (Region region in regions)
{
if (!region.remap)
{
continue;
}
currRegionID++;
int oldID = region.id;
foreach (Region r in regions)
{
if (r.id == oldID)
{
r.id = currRegionID;
r.remap = false;
}
} //foreach
} //foreach
field.setRegionCount(currRegionID + 1);
iter.Reset();
while (iter.MoveNext())
{
OpenHeightSpan span = iter.Current;
if (NULL_REGION == span.regionID())
{
continue;
}
else
{
//真正re-map一下
span.setRegionID(regions[span.regionID()].id);
}
}
#endregion
} //apply
public void apply(OpenHeightfield field)
{
if (null == field)
{
Logger.LogError("[CLeanNullRegionBorders][apply]field null");
return;
}
int nextRegionID = field.regionCount();
OpenHeightfield.OpenHeightFieldIterator iter = field.GetEnumerator();
while (iter.MoveNext())
{
OpenHeightSpan span = iter.Current;
if (span.flags != 0)
{
continue;
}
span.flags = 1;
OpenHeightSpan workingSpan = null;
int edgeDirection = -1;
if (NULL_REGION == span.regionID())
{
//找到Border Span第一个非空的邻居
edgeDirection = getNonNullBorderDrection(span);
if (-1 == edgeDirection)
{
continue;
}
//起点Span为有所属Region的Span
//而行走方向为 null Region所在的方向
workingSpan = span.getNeighbor(edgeDirection);
//转180度
edgeDirection = NMGenUtility.AntiDir(edgeDirection);
}
else if (!mUseOnlyNullSpans)
{
//起点Span为 null Region的Span
//而行走方向即为有所属 Region 的 Span
edgeDirection = getNullBorderDrection(span);
if (-1 == edgeDirection)
{
continue;
}
workingSpan = span;
}
else
{
continue;
}
//上面两个分支都会保证workingSpan是有所属Region的
//而Dir 即是 Region 为 Null Region的Dir
bool isEncompassedNullRegion = processNullRegion(workingSpan, edgeDirection);
if (isEncompassedNullRegion) //确定以这个Span为起点的Region，是一个单一Region，并且内含了一个Null Region
{
//如果是完全包含了不可走的NullRegion ，就将这个Region分割成两个Region
partialFloodRegion(workingSpan, edgeDirection, nextRegionID);
nextRegionID++;
}
}
field.setRegionCount(nextRegionID);
iter.Reset();
while (iter.MoveNext())
{
iter.Current.flags = 0;
}
}
public ContourSet build(OpenHeightfield sourceField)
{
if (null == sourceField ||
0 == sourceField.regionCount())
{
Logger.LogError("[ContourSetBuilder][build]sourceField Invalid");
return(null);
}
ContourSet result = new ContourSet(sourceField.boundsMin(),
sourceField.boundsMax(),
sourceField.cellSize(),
sourceField.cellHeight(),
sourceField.regionCount());
int discardedContours = 0;
/*
* If a span has no connections to external regions or is
* completely surrounded by other regions (a single span island),
* its flag will be zero.
*
* If a span is connected to one or more external regions then the
* flag will be a 4 bit value where connections are recorded as
* follows:
* bit1 = neighbor0
* bit2 = neighbor1
* bit3 = neighbor2
* bit4 = neighbor3
* With the meaning of the bits as follows:
* 0 = neighbor in same region.
* 1 = neighbor not in same region. (Neighbor may be the null
* region or a real region.)
*/
OpenHeightfield.OpenHeightFieldIterator iter = sourceField.GetEnumerator();
while (iter.MoveNext())
{
OpenHeightSpan span = iter.Current;
span.flags = 0; //默认没有与任何外部Region相连
if (NULL_REGION == span.regionID())
{
continue;
}
for (int dir = 0; dir < 4; ++dir)
{
int nRegionID = NULL_REGION;
OpenHeightSpan nSpan = span.getNeighbor(dir);
if (nSpan != null)
{
nRegionID = nSpan.regionID();
}
//这里是反常操作，先将相同的当作是1，然后统一位反
if (nRegionID == span.regionID())
{
span.flags |= 1 << dir;
}
} // for
//1111111
span.flags ^= 0xf;
if (span.flags == 0xf) //证明四个邻居都不在同一个Region或者是一个孤岛Span
{
//重置这个位置
span.flags = 0;
discardedContours++;
Logger.LogWarning("[ContourSetBuilder][apply]Island Span|{0}|{1}", span.regionID(), discardedContours);
}
} //while iter
List <int> workingRawVerts = new List <int>(256);
List <int> workingSimplifiedVerts = new List <int>(64);
iter.Reset();
while (iter.MoveNext())
{
OpenHeightSpan span = iter.Current;
if (NULL_REGION == span.regionID() ||
0 == span.flags) //flag等于0的话，是前面那些孤岛Span
{
continue;
}
workingRawVerts.Clear();
workingSimplifiedVerts.Clear();
//找到第一个不是同一个Region的Span
int startDir = 0;
while (isSameRegion(span, startDir))
{
startDir++;
}
buildRawContours(span,
iter.widthIndex(),
iter.depthIndex(),
startDir,
ref workingRawVerts
);
generateSimplifiedContour(span.regionID(),
workingRawVerts,
ref workingSimplifiedVerts);
//TODO 为什么小于12个顶点就不行呢？
if (workingSimplifiedVerts.Count < 12)
{
Logger.LogWarning("[ContourSetBuilder][build]Discarded Contour|{0}|{1}|", span.regionID(), discardedContours);
discardedContours++;
}
else
{
result.add(new Contour(span.regionID(),
workingRawVerts,
workingSimplifiedVerts));
}
} // while iter
if (discardedContours > 0)
{
Logger.LogWarning("[ContourSetBuilder][build]Contours not generated|{0}|", discardedContours);
}
if (result.size() + discardedContours
!= sourceField.regionCount() - 1)
{
for (int regionID = 1; regionID < sourceField.regionCount(); ++regionID)
{
int regionMatches = 0;
for (int iContour = 0; iContour < result.size(); ++iContour)
{
if (regionID == result.get(iContour).regionID)
{
regionMatches++;
}
}
if (regionMatches > 1)
{
Logger.LogError("[ContourSetBuilder][build]More than |{0}|{1}", regionID, regionMatches);
}
} // for
for (int iContour = 0; iContour < result.size(); ++iContour)
{
Contour contour = result.get(iContour);
if (contour.regionID <= 0)
{
Logger.LogError("[ContourSetBuilder][build]null region contour");
}
else if (contour.regionID >= sourceField.regionCount())
{
Logger.LogError("[ContourSetBuilder][build]contour out of range|{0}", contour.regionID);
}
} // for
Logger.LogError("[ContourSetBuilder][build]Error{0}|{1}|{2}|{3}",
sourceField.regionCount() - 1,
result.size() + discardedContours,
result.size(),
discardedContours
);
return(null);
}
return(result);
} // build