Topic: Direct a line along a spline or curved Polyline

[Coder]

Hello everyone .

How can I copy or create a line along a spline or curved polyline with respect to the rotation of the angle ?

I prefer it with code and not commands please .

My main problem is with the rotation of the curve .

Many thanks . 

[Lee Mac]

Use the vlax-curve-* functions to determine the point at a specific distance and first derivative (direction of the tangent) at such point.

e.g.:

Code - Auto/Visual Lisp: [Select]

1. (setq pnt (vlax-curve-getpointatdist <entity> <distance>))
2. (setq ang (angle '(0.0 0.0 0.0) (vlax-curve-getfirstderiv <entity> (vlax-curve-getparamatpoint <entity> pnt))))

[Coder]

Thanks Lee , That's works great . 

Can I ask you why you have started  the angle from '(0. 0. 0.) to the derivation ?

Any extra information about the meaning of derivation would be certainly thankful 

[Lee Mac]

Thanks Lee , That's works great . 

You're welcome 

Can I ask you why you have started  the angle from '(0. 0. 0.) to the derivation ?

Any extra information about the meaning of derivation would be certainly thankful 

Because the first derivative (tangent vector) is expressed in WCS relative to the origin (0.0 0.0 0.0)

For more information: First Derivative