arc 2pts and 2 tangent

hello everydoby,

I have a problem to create an arc a little bit special: i would create an arc with 3 points but i need use the 2 tangent of the extrem point. can someone help me please i am block with this problem

Replies to This Discussion

Permalink Reply by David Rutten on April 17, 2013 at 3:40am

A single arc is defined either by three (non-co-linear) points, or by two end-points and a tangent. Anything more will overconstrain the problem and not permit a solution.

Perhaps you can provide a picture of exactly what it is you have and what it is you're after?

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Doui on April 17, 2013 at 4:22am

yep its difficult to explain it so this is the picture of what i want:yes in fact that is not an arc but a curve. i have 2 curve and one circle and i want create a curve which is tangent with the 2 extrem curve and pass through the quad point of circle.. the orange line is nearly what i want. tks for helping me

Permalink Reply by Doui on April 17, 2013 at 4:35am

this is picture of the methode i first use for create this curve in 3 step: first create tangent arc with 3 circle for the center part,next use the 2 circle to create the join of my original curve and center parthere i move the 2 circle for you seen the 3 part of the curve i want.

Permalink Reply by David Rutten on April 17, 2013 at 4:50am

I attached a file with two solutions. One creates an interpolated curve through a mid-point with end-tangent control. The other creates two interpolated curves that meet tangentially at a circle.

The length of the tangent vectors is important, so you may have to add a custom multiplier to get some control over that.

David Rutten

david@mcneel.com

Poprad, Slovakia

Attachments:

BlendCrv.gh, 12 KB

Permalink Reply by David Rutten on April 17, 2013 at 6:02am

Incidentally the next release will have both a [Blend Curve] and [Blend Curve Through Point] component. It doesn't allow you to control the tangency of the blend at the point though.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Doui on April 17, 2013 at 7:22am

first thanks you for time passed to help me! i have try all your solution but they didn't resolve my problem.. moreover i just have this component and not your:i will try to be more precise.i begin with two curve and an arc and this is what i want to do (red line is my parametric problem):moreover you have to know that the angle between the two curves change with sliders and radius of arc which do the 2 curve change too. thanks for time you keep too help me

Permalink Reply by Doui on April 17, 2013 at 7:23am

Permalink Reply by Danny Boyes on April 17, 2013 at 3:53am

Sounds like you want to blend two curves together with both position and tangency (C1) rather than create an arc.

Permalink Reply by Danny Boyes on April 17, 2013 at 4:41am

How about something like this:

Attachments:

Doui_ArcHelp.gh, 6 KB

Permalink Reply by Doui on April 17, 2013 at 7:30am

thanks you very much for time deal too help me! you solution is the nearlest, but i work in (xy)plan and your is in xz, i try to change the propriety to move it in right plan but not in success , i obtain this form....

Permalink Reply by Danny Boyes on April 17, 2013 at 7:52am

The Z Vector has an Expression -F so that the lowest point of the circle is the intersection. Just change this to the Y vector with -F as the expression or alternatively -1 as the value.

Permalink Reply by Doui on April 17, 2013 at 8:29am

its what i do and the picture was doing with this codebut the problem is still here.