/// <summary>
/// 确保垂直方向上两个Span之间的区域不会卡头
/// </summary>
/// <param name="field"></param>
private void markLowHeightSpans(SolidHeightfield field)
{
SolidHeightfield.SolidHeightfieldIterator iter = field.GetEnumerator();
while (iter.MoveNext())
{
HeightSpan span = iter.Current;
if ((span.flags() & SpanFlags.WALKABLE) == 0)
{
continue;
}
int spanFloor = span.max(); //SolidSpan的max，其实就是OpenSpan的底部
int spanCeiling = (span.next() != null)
? span.next().min() : int.MaxValue;
if (spanCeiling - spanFloor <= mMinTraversableHeight)
{
span.setFlags(span.flags() & ~SpanFlags.WALKABLE);
}
}
}
/// <summary>
/// 边缘裁剪，那种像断崖式的Span也不可走的
/// </summary>
/// <param name="field"></param>
private void markLedgeSpans(SolidHeightfield field)
{
SolidHeightfield.SolidHeightfieldIterator iter = field.GetEnumerator();
while (iter.MoveNext())
{
HeightSpan span = iter.Current;
if ((span.flags() & SpanFlags.WALKABLE) == 0)
{
continue;
}
int widthIndex = iter.widthIndex();
int depthIndex = iter.depthIndex();
int currFloor = span.max();
int currCeiling = (span.next() != null)
? span.next().min() : int.MaxValue;
int minDistanceToNeighbor = int.MaxValue;
for (int dir = 0; dir < 4; dir++)
{
int nWidthIndex = widthIndex
+ BoundeField.getDirOffsetWidth(dir);
int nDepthIndex = depthIndex
+ BoundeField.getDirOffsetDepth(dir);
HeightSpan nSpan = field.getData(nWidthIndex, nDepthIndex);
if (null == nSpan)
{
//TODO 这里没有搞懂为啥是 -mMaxTraversableStep - currFloor,是为了比-mMaxTraversableStep更小，以便直接判断不能行走吗？
// 用大可行的距离，再减去currFloor，得到的肯定是一个更小的值。
// currFloor - mMaxTraversableStep 是一个最大允许的落差地板距离。注意这里只考虑下落的情况
minDistanceToNeighbor = Math.Min(minDistanceToNeighbor, -mMaxTraversableStep - currFloor);
continue;
}
/*
* 先考虑一种特殊情况 ，那就是
* 那就是nSpan.min也比currFloor要高，那么对应的
* 的邻居相当于也是没有Floor的，所以默认取-mMaxTraversableStep吧。
*/
int nFloor = -mMaxTraversableStep;
int nCeiling = nSpan.min();
//当前Span所处列的currCeiling和邻居的nCeiling相比，取最低的
if (Math.Min(currCeiling, nCeiling) - currFloor > mMinTraversableHeight)
{
minDistanceToNeighbor = Math.Min(minDistanceToNeighbor, (nFloor - currFloor));
}
for (nSpan = field.getData(nWidthIndex, nDepthIndex); nSpan != null; nSpan = nSpan.next())
{
nFloor = nSpan.max(); //现在才开始用max考虑真正存在的Floor
nCeiling = (nSpan.next() != null)
? nSpan.next().min() : int.MaxValue;
if (Math.Min(currCeiling, nCeiling) - Math.Max(currFloor, nFloor) > mMinTraversableHeight)
{
minDistanceToNeighbor = Math.Min(minDistanceToNeighbor, (nFloor - currFloor));
}
}
}
//如果最近的距离比较最大掉落还小的放在，那么就是不可行走的
if (minDistanceToNeighbor < -mMaxTraversableStep)
{
span.setFlags(span.flags() & ~SpanFlags.WALKABLE);
}
}
}