Need help tweaking my first attempt at a Grasshopper definition

I've been taking tutorials for a while, and I recently decided to try making a definition of my own. I was hoping to get some of you all to take a look at the file to see how I could simplify it. As it is, it seems like I had to do too much work to get my result, plus some occasional errors occur.

I am trying to make a set of parametric stairs based off of the contour lines of a lofted surface. The surface is based off the front edge curves of a series of six curved posts. The lofted surface will not be baked, it is only to create a starting point for the contour stairs. As I move the control points of the posts back and forth (orthographically), the loft surface changes and the stairs regenerate and hug the posts.

Problems:
- when I bend the posts using the control points, occasionally one or more stairs will disappear. Not sure why this is happening.
- definition might be more complicated than necessary.

Please take a look at the rhino file and the grasshopper file and tell me what you think.
Thanks!

- Sky

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Replies to This Discussion

Permalink Reply by Matt Gaydon on April 5, 2010 at 2:00pm

Hi Sky

Had a little play/tweak with the code and posted it below. I have rather re-written some parts of it to make its a simple as i can but still giving you all the original controls. Hope this edit will help with your learning.

Matt

Attachments:

contoursteps_w_notes MG Re-Edit.ghx, 405 KB

Permalink Reply by SkyC on April 7, 2010 at 12:33am

Hi Matt, and others,

I was able to get rid of the bump by creating the loft surface from curves that were offset to the center of each post. Works nicely.

There is one thing that I haven't been able to solve with your definition, though, and I was wondering if you or anyone else might have a solution. It seems that as I move the control points of the posts to create different undulating stair geometry, the stairs themselves do not keep a uniform tread depth. In my original definition, this was something I had difficulty figuring out, but managed to do so by offsetting those projected contour lines. Your definition doesn't use the contour lines, it seems. While this creates a neat ability to move the posts all over the place and still get stair geometry, move or rotate them too much and you get stairs that are just inches wide (see attached pic).

Is there a way to make the stairs always have a uniform tread depth but behave in a similar way?

Attachments:

tinytreads.jpg, 682 KB

Permalink Reply by Danny Boyes on April 7, 2010 at 2:10am

Hi SkyC,

Why don't you use your methodology still but take advantage of the grafted tree branches demonstrated in Matt's definition. Believe in the Tree! This way you can add elements to the model with out having to copy and paste your components over and over. The only thing to watch out for in this kind of approach is flattening any data streams will produce undesired effects. But from a quick look there doesn't seem to be any in yours. When you get to the loft component the streams will need to be flattened in order to loft correctly.

Permalink Reply by SkyC on April 7, 2010 at 9:53am

Danny,

Yeah, I haven't worked on trees too much yet, but when I go back and look over Matt's stuff hopefully it will help me figure it out.
-Sky

Permalink Reply by Matt Gaydon on April 7, 2010 at 2:23am

Hi Sky

The reason your stair are changing depth with the new code i edited/wrote is that it is based on 2 SDL Lines at the ends of the offset contour section lines using with the direction of these lines being denoted by from the Y Axis of the Horizontal frame at the start of each offset line. This works fine if the end poles are parallel but soon soon as one changes angle as you can see the system 'fails'. To fix this change the single H Frame Component to a H Frames Component with N input = 1. You will need to also inset a Cull Pattern Component (Boolean Pattern = True False) between the new H Frames component and the P input of the Offset Crv Component to cut the number of planes per branch back down to 1 or you will get duplicate offset crvs.

Hope This Helps

Matt

Permalink Reply by SkyC on April 7, 2010 at 9:56am

I tried this and it worked. Thanks again Matt, you're a master!
-Sky

Permalink Reply by SkyC on April 5, 2010 at 9:41pm

Matt

Thank you! This is exactly what I needed - the same thing I built but structured differently using some more advanced techniques. I'll be going back to figure out how exactly you did that.

I think that something that might improve the stair curvature would be to change the curves used to create the loft from the two outer edge curves of the posts to just one curve centered on the outer face of each post. As it is, using the two edge curves right next to each other creates a strange looking bump in the stair curvature at each post. I'll see if I can get that going.

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