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View Full Version : how can I connect a line and a arc by mel


yanmaznecip
05-25-2010, 11:38 AM
Hi every body, I have a line in some length and a constant radius curve in some degree and both of them can be located in maya scene in any orientation. And I want to joint line and curve by using a spiral and I want the derivative in joint points must equal to zero. Do you suggest anything related to my problem.

bst rgrds

ny

NaughtyNathan
05-25-2010, 12:15 PM
I'm not sure exactly what you mean necip, and I have no idea what your end result should be... I don't see how you can calculate an arbitrary spiral from a line and an arc... (well, I can think of how, but I'm pretty sure this is not what you're asking)
could you post an example image to show what you mean/want?

:nathaN

yanmaznecip
05-25-2010, 01:10 PM
Hi Nathan,
http://forums.cgsociety.org/attachment.php?attachmentid=153640&stc=1

In picture there are one red constant radius curve, one green line and one purple purple spline.
Red curve and green line are coming from third party source. What I am looking for is that the mathematical polynomial formula of the purple spline. The only need which should be met is that when I join red circle purple spline and green line, derivatives must equal to zero at point 1 and point 2.

bst

ny

NaughtyNathan
05-25-2010, 01:21 PM
ah! ok, that's not a spiral... you just want to join two curves together with a third curve and keep the tangents smooth?

Edit Curves > Curve Fillet does this, you just have to make sure you set the correct parameters. in mel for example:

filletCurve -ch on -rpo 0 -t 0 -jn 0 -cir 0 -fb 1 -bc 1 -d 0.5 -b 0 "curve1.u[2]" "curve2.u[0]";

(make sure you specify the correct .u param for both curve end points)

:nathaN

yanmaznecip
05-25-2010, 01:36 PM
Hi Nathan,

I am trying to write an text file as output of the lines present in scene. I could represent line with straight-line equations "y = mx + b" and represent curve with equation of a circle "x2 + y2 + Dx + Ey + F = 0". and do I have chance to get the mathematical equation of the spline which I draw by using your command below.
filletCurve -ch on -rpo 0 -t 0 -jn 0 -cir 0 -fb 1 -bc 1 -d 0.5 -b 0 "curve1.u[2]" "curve2.u[0]";
bst

ny

NaughtyNathan
05-25-2010, 01:46 PM
???

I have no idea but I assume so... although there are almost an infinite number of possible connecting curves, depending on what your parameters are...?

but I can't help with any maths I'm afraid, I don't even understand how formulae can represent a curve! :D :eek:

good luck.
:nathaN

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