IGES TYPE 142 QUERY

Hi,

Say, I have a rational b spline curve(type 126) with form type = 0(form
of curve must be determined from the rational b spline parameters).

This curve is refered in index(3) of the parameter data of type 142 ie
pointer to the directory entry of the entity that contains the
definition of the curve B in the parametric space (u,v) of the surface
S.

So I wonder what should I defined in CPTR(index no.4 in paramter data)
in type 142(curve on a parametric entity), ie pointer to the directory
entry of the curve C?

Thank you.

jeff

 

Jeff,

Are you trying to map IGES entities ???

Hey Cliff !!! A golden opertunity for an on-topic (non political) response !

Mark

 

WHAT "political" ?????

If I knew a bit better exactly what they were asking for ..... I
used to (long, long ago) manipulate IGES files using TECO ...
and do still have the IGES docs .... (V 2 & 3 only).

"CPTR" ?

http://www.coe.org/forums/messageview.cfm?catid=3&threadid=1962&STARTPAGE=1

(And I may not know either <G>.)

Perhaps they should create such a curve in their CAD system,
export it as IGES & then look at the file?

BTW, Is jb sick?
<G>

 

Just remembered, sorry, probably deleted the post ....
Someone asked about an IGES "curve on surface" entity IIRC.
I was planning on waiting a day or so to se if someone else
replied ....

That one allows the curve to be reinterpolated/recreated
on the system that got it to that system's precision and
possible associativity "standards".
Otherwise you'd just have a curve and a surface but
the curve might not actually be within some tolerance
of the surface or on it ...... even if it started out that
way.