关于曲线法线的问题

rielzhou

请问如何能获取曲线上任意点处的法线方向，请哪位高手指点一下！

alin

Download VLAX.cls and Curve.cls... Then the following codes can find out the tangent direction of a point on curve.

Sub TEST()
Dim C As Curve
Dim objCur As AcadEntity
Dim pickPnt As Variant
Dim closePnt As Variant
Dim paramatclosePnt As Double
Dim tangentatclosePnt As Variant
Set C = New Curve
ThisDrawing.Utility.GetEntity objCur, pickPnt, "SELECT A CURVE:"
Set C.Entity = objCur
closePnt = C.GetClosestPointTo(pickPnt)
paramatclosePnt = C.GetParameterAtPoint(closePnt)
tangentatclosePnt = C.GetFirstDerivative(paramatclosePnt)

Dim objRay As AcadRay
Dim origin(2) As Double
Dim pt2(2) As Double
origin(0) = 0#: origin(1) = 0#: origin(2) = 0#
pt2(0) = tangentatclosePnt(0): pt2(1) = tangentatclosePnt(1): pt2(2) = tangentatclosePnt(2)
Set objRay = ThisDrawing.ModelSpace.AddRay(origin, pt2)
objRay.Move origin, closePnt
End Sub