help with planar geometry

Hello,
I have just started to teach myself Grasshopper. I would appreciate some help in figuring out how I should create a parametric definition of my geometry. There is an image attached and the following points should help:

1. Origin, fixedpt-1 and fixedpt-2 are fixed. However, these distances may change at a later date.
2. The radius of Arc-1 is fixed.
3. Arc-2 must be drawn such that it passes through fixedpt-2 and is tangential to Arc-1 as shown. Radius of Arc-2 is flexible.

I have tried modeling the above but am not really getting anywhere. I have attached my grasshopper file in case anyone is interested.

I am not looking for a full solution, but just some direction. I will appreciate any and all help. Thank you.

Attachments:

090730_basegeom.ghx, 253 KB

Replies to This Discussion

Permalink Reply by miron on July 30, 2009 at 9:44pm

Hello Sameer,

I might be able to help you, but you'd need to give a btter explanation. I sit on 4th south or if you want I can just come up upstairs.

Permalink Reply by Daniel Xiong on July 30, 2009 at 9:50pm

Hi Sameer,
I have attached the files below, hope it would help you a little bit.

Attachments:

SolutionSameer.rar, 11 KB

Permalink Reply by Sameer Kumar on July 31, 2009 at 7:55am

Daniel,

The file you have posted is a partial or corrupted. Could you please post again?

Thanks for your time!

Sameer

Permalink Reply by Daniel Xiong on July 31, 2009 at 9:20pm

Sameer,
Maybe it is because the file I attached last time is a .rar file so you have to use winrar to unzip it. I have attached the zip file below.

Attachments:

solutionSameer.zip, 13 KB

Permalink Reply by Sameer Kumar on August 3, 2009 at 1:41pm

Daniel,

Thanks for reposting. Rar file was not the problem... for some reason it would download a 1kb file everytime I tried.

Your definition is beautiful and elegant. It was also quite helpful for me conceptually. However, there are a few other constraints that I am looking to build into this geometry which I did not clearly express earlier.

I have developed my own definition of what I would like to achieve and am attaching it below. However, it is far from elegant or efficient; in fact, after seeing your solution, I can say that mine is simply dumb! I would really appreciate if you (or anyone else) would comment on it and help me refine it.

You shall see that to achieve a tangential curve, I have tried to find the center of this larger curve by intersecting a radial line of the small curve and a perpendicular bisector of the line joining fixedpts 1 and 2. I still cannot understand how you have achieved your tangential curve using "Evaluate Curve" and "SED Arc"... I could not make it work.

Also, could someone explain "bake" please? I have ended up with circles where I wanted arcs. How do I extract arcs using the circles?

Thanks a lot!

Attachments:

090803_basegeom.ghx, 325 KB

Permalink Reply by Daniel Xiong on August 3, 2009 at 9:01pm

Hi Sameer,
After viewing your file, I guess you might want to add some parameters to control the angle of Arc1.
I think your problem might be using too many Circles while you want arcs. And you don't have to use many components to generate a point. You can just pick it up on the screen by Point component or pick up a point which you create before in Geometry component.
I have attached the file below. Hope it will help.

Attachments:

SolutionSameerKumarX.zip, 23 KB

Permalink Reply by Sameer Kumar on August 6, 2009 at 10:35pm

Thanks for all your help Daniel. Regarding measuring the angles for defining arcs, is there a way to change the start point for the measurement? Zero degree always defaults to +ve X axis. What if I wanted to measure the angle from a 45 deg line?

In any case, for now I have what I set out for. I may come back with more questions later. Thanks again.

Permalink Reply by Rafi on August 1, 2009 at 2:32am

Hallo Daniel,

Maybe you have a clue how to convert a nurbs curves to separated arcs.

Permalink Reply by Daniel Xiong on August 1, 2009 at 8:04am

Hi Rafi,
I really have no clue about that. I think the key problem of this isue is where to separate the curve. I tried to divide the curve evenly but it works poorly. The files are attached below and you can see how poor it works if someone try to divide the curve evenly.

Attachments:

CrvToArcs.zip, 14 KB

Permalink Reply by Rafi on August 1, 2009 at 10:29am

Hallo Daniel,

Tanks for replay, it would be much better if those arcs going according the domain curve with individual arc length.
-Is it possible to analysing the rotate angle on the axis by 3d nurbs curve?

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