private void ComputeCrossPoints()
{
int preIdx = 0;
bool preIsRight = _originalPoints[preIdx].X >= _X;
bool isRight = false;
for (int i = 1; i < _originalPoints.Count; i++)
{
preIsRight = _originalPoints[preIdx].X >= _X;
isRight = _originalPoints[i].X >= _X;
if (isRight ^ preIsRight)
{
CrossPoint pt = new CrossPoint(new ShapePoint(_X, (_originalPoints[preIdx].Y + _originalPoints[i].Y) / 2d), -1);//unsort
_crossPoints.Add(pt);
}
preIdx = i;
}
if (_crossPoints.Count > 0)
{
_crossPoints.Sort();
for (int i = 0; i < _crossPoints.Count; i++)
{
_crossPoints[i].Index = i;
}
}
}
private void GetActivePart(ShapePoint pt, ShapePoint prePoint)
{
CrossPoint crossPt = null;
//获取跨分割线的交点
if (prePoint != null)
{
crossPt = GetCrossPoint(pt, prePoint);
if (crossPt == null)
{
throw new Exception("获取一对点的交点失败。"); //不会出现这样的错误。
}
}
//
if (_activePartCollection.Count == 0)
{
_activePart = new PartStatus();
_activePartCollection.Add(_activePart);
goto endLine;
}
else
{
//获取相邻的环
foreach (PartStatus part in _activePartCollection)
{
bool isLessThan = false;
if (part.IsNear(crossPt.Index, out isLessThan))//相邻
{
if (_activePartCollection.Equals(_leftParts) && isLessThan)
{
_activePart = part;
goto endLine;
}
if ((_activePartCollection.Equals(_rightParts) && !isLessThan))
{
_activePart = part;
goto endLine;
}
}
}
_activePart = new PartStatus();
//将新建的环加入活动环集合
_activePartCollection.Add(_activePart);
goto endLine;
}
endLine:
//将当前交点与活动环关联
if (crossPt != null)
{
if (_prePartStatus != null)
{
_prePartStatus.AddLinkeCrossPointIndex(crossPt.Index);
}
}
_prePartStatus = _activePart;
}