public DrawObject ExtendDrawObject(DrawObjectExtendInfo extendInfo)
{
if (extendInfo.ExtendedDrawObject is TDrawObject tDrawObject)
{
return(ExtendDrawObject(tDrawObject, extendInfo));
}
return(null);
}
protected abstract DrawObject ExtendDrawObject(TDrawObject drawObject, DrawObjectExtendInfo objectExtendInfo);
protected override DrawObject ExtendDrawObject(Line line, DrawObjectExtendInfo objectExtendInfo)
{
var intersectPoints = objectExtendInfo.IntersectPositions;
var extendArea = objectExtendInfo.ExtendArea;
if (line == null)
{
return(null);
}
if (intersectPoints == null)
{
return(null);
}
if (extendArea == null)
{
return(null);
}
var startIsInArea = objectExtendInfo.ExtendArea.Contains(line.Line2D.Start);
var endIsInArea = objectExtendInfo.ExtendArea.Contains(line.Line2D.End);
if (startIsInArea == endIsInArea)
{
return(null);
}
(Vector2D rayStartPos, Vector2D rayEndPos) = startIsInArea ? (line.Line2D.End, line.Line2D.Start) : (line.Line2D.Start, line.Line2D.End);
var rayVector = rayEndPos - rayStartPos;
//检查是否在射线的延长线上;
intersectPoints = intersectPoints.Where(p => {
if (p.IsInLine(line.Line2D))
{
return(false);
}
var rayStartToPointVector = p - rayStartPos;
var cross = rayStartToPointVector.Cross(rayVector);
var dot = rayStartToPointVector.Dot(rayVector);
if (cross.AreEqual(0) && dot.AreEqual(rayStartToPointVector.Modulus() * rayVector.Modulus()))
{
return(true);
}
return(false);
}).OrderBy(p => p.Distance(line.Line2D.Start)).ToArray();
if (intersectPoints.Length != 1)
{
return(null);
}
//寻找距离射线起点最近的点;
Vector2D closestPoint = null;
double shortestDis = 0;
foreach (var point in intersectPoints)
{
var thisDis = point.Distance(rayStartPos);
if (closestPoint == null)
{
closestPoint = point;
shortestDis = thisDis;
continue;
}
if (thisDis < shortestDis)
{
closestPoint = point;
shortestDis = thisDis;
}
}
return(new Line(new Line2D(closestPoint, rayStartPos)));
}
