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How to tell Start Point of a Spline


Proctor

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Hello:

 

when I use the list command to get properties of my spline, i see 4 control points listed(see output below):

when debugging, i would think that the start point would be equivalent to either the geometric max or min point therefore it should

be either X = 177.5898 , Y = 52.1529 , Z = 0.0000

or

X = 185.3957 , Y = 51.9440 , Z = 0.0000

 

but according to my code, it's saying that the start points is:

X = 180.1918 , Y = 52.0833 , Z = 0.0000

 

and I'm having a hard time understanding how this could be the start point?

 

thanks for your help,

Proctor

 

Select objects: 1 found

Select objects:

SPLINE Layer: "2 PER FT LT"

Space: Model space

Handle = 104d

Length: 7.8087

Order: 4

Properties: Planar, Non-Rational, Non-Periodic

Parametric Range: Start 0.0000

End 7.8087

Number of control points: 4

Control Points: X = 185.3957 , Y = 51.9440 , Z = 0.0000

X = 182.7937 , Y = 52.0136 , Z = 0.0000

X = 180.1918 , Y = 52.0833 , Z = 0.0000

X = 177.5898 , Y = 52.1529 , Z = 0.0000

Number of fit points: 2

User Data: Fit Points

X = 185.3957 , Y = 51.9440 , Z = 0.0000

X = 177.5898 , Y = 52.1529 , Z = 0.0000

Fit point tolerance: 1.0000E-10

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Draw a spline with the first point at 0,0,0. Then list it, the first control point (start of the spline) will be listed as 0,0,0

You can test it with this

(defun c:test ()
 (setq obj (vlax-ename->vla-object (car(entsel))))
 (vlax-curve-getStartPoint obj)
 )

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Hello lpseifert: thank you for your help.

 

My apologies that I didn't indicate I'm coding in .net api.

I drew a few splines as suggested and when i did list on these,

it always lists the start point first. would you agree that this is what it does? does it list the start point first and the end point last?

 

perhaps getting the start point in .net api is different than for other objects so I will check that out.

 

thanks again for taking the time to reply.

Proctor

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