// 已知曲线(直线、圆曲线)和其上一点距曲线起点的沿线距离,
// 计算该点的坐标, 以及该点切向的垂直方向向量lateral
public static (XbimPoint3D pt, XbimVector3D vec) GetPointOnCurve(IIfcCurveSegment2D c, double dist)
{
if (c is IIfcLineSegment2D line)
{
return(GetPointOnCurve(line, dist));
}
if (c is IIfcCircularArcSegment2D arc)
{
return(GetPointOnCurve(arc, dist));
}
throw new NotImplementedException("Transition curve not supported for now");
}
public static (XbimPoint3D pt, XbimVector3D vec) GetPointByDistAlong(IItemSet <IIfcAlignment2DHorizontalSegment> horSegs, double dist)
{
int i = 0;
IIfcCurveSegment2D cur = null;
for (; i < horSegs.Count; i++)
{
cur = horSegs[i].CurveGeometry;
if (dist > cur.SegmentLength + Tolerance)
{
dist -= cur.SegmentLength;
}
else
{
break;
}
}
if (cur == null)
{
throw new ArgumentNullException("horSegs");
}
return(GetPointOnCurve(cur, dist));
}
public static XbimPoint3D GetPlacementPoint(IIfcCurveSegment2D c, double dist,
double verticalOffset, double lateraloffset)
{
XbimPoint3D Point3D = new XbimPoint3D();
if (c is IIfcLineSegment2D line)
{
(XbimPoint3D pointOnCurve, XbimVector3D vecOnCurve) = GetPointOnCurve(line, dist);
var zAxis = new XbimVector3D(0, 0, 1);
var vecoff = vecOnCurve.CrossProduct(zAxis);
Point3D = (pointOnCurve + vecoff * lateraloffset + zAxis * verticalOffset);
//return Point3D;
}
if (c is IIfcCircularArcSegment2D arc)
{
(XbimPoint3D pointOnCurve, XbimVector3D vecOnCurve) = GetPointOnCurve(arc, dist);
var isCCW = (bool)arc.IsCCW.Value;
var zAxis = new XbimVector3D(0, 0, 1);
var start2center = isCCW ? zAxis.CrossProduct(vecOnCurve) : vecOnCurve.CrossProduct(zAxis);
Point3D = (pointOnCurve + start2center * lateraloffset + zAxis * verticalOffset);
//return Point3D;
}
return(Point3D);
}
