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Topics related to the Grasshopper-ARCHICAD Connection and the various tasks that can be achieved with it.

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By Karol Lozinski
I'm currently planning on doing my bachelor degree in architecture in ArchiCAD and Grasshopper. Recently I tried doing some test project just to see what can I do. My target is to design a small house for an atom family. Though as you might think - it'll be a parametric one. And I encountered exactly what's in the title. So here it goes:
1. Something is wrong with the measuring units in the complex profiles. I met this problem while making I-beam. In ArchiCAD it had 127/76 mm while in Grasshopper i had 127000/76200mm so a little bigger.

2. I'm unable to turn off the preview. I mean when I delete something in Grasshopper/Rhino it still exists in ArchiCAD. I have to unlock it and then delete it.

3. Coordinates for points seem broken. They have to be multiplied 1000 times to match.

4. Now one of the most important. Is it possible to somehow SHOW Grasshopper where are already made in ArchiCAD objects. Even if they'll remain still. For example I want to make a parametrical roof. Do I have to model whole building from scratch in Grasshopper or is there some fast way to "import" existing scene so I can limit my work with Grasshopper only to parametrical one.

5. Is it possible to make "points" as controlling points in AC? Like, if I'd like to make a beam in a desired place which I will mark by that point and then I will "show" Grasshopper that point and tell it to make an object in there so I can control it within grasshopper. I tried ti do this using AC Control Point but when I click "Send changes" button, Grasshopper and Rhino crush immediately. It only happens then, with control points.

6. It seems that "move" component won't work with "2D curve" component connected directly.

It is possible that some of those problems are outdated. I was playing around in Grasshopper a few months ago, before summer break, but now I plan to try something new and it would be nice to know what to do. :) I appreciate any answer to any of those questions. Please help, you guys, are my only hope. :) Thanks in advance!

By Karol Lozinski
Nobody? At least one answer, at least anything... Where to look to find answers. Maybe some books, articles, videos, anything? :(
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By leceta
i have no clear answers, but let´s see:

1- check your rhino units. Advice: work always in meters, both in rhino and archicad. My experience says that plugin, nowadays, likes the things to be so

2- No idea, may be a bug, may be who knows what... I personally don't remember this issue before...

3- As in the first answer, check system unit, work in meters.

4- you could reference ArchiCAD polylines into Grasshopper in order to locate spatially your geometry.

5- yes, using point parameters in GH. Theoretically, this is the idea behind this component. If this doesn't work for you, means that there is some bug there (i would suspect so)
6- no idea
By Karol Lozinski
First of all THANK YOU soooo much for a reply! For helping me out! And now, just to be sure... Sooo there isn't other way to show ArchiCAD project in Rhino? Let's say I want to make a parametric roof so i have to use mutual things for both programs such as - as you said - polyline? And, let's say, I want to have my roof laying on the columns. So all I have to do is... create a polyline in AC on the floor plan, on the top of the columns, then show that polyline to Grasshopper and then, using those polylines as known points in AC create desired roof, right?

Now, if I want to keep my attachment parametrical, so when I move my columns in AC the shape of the roof will change, the only thing I have to do is group each column with corresponding polyline, so the polyline will move when I'll move my column? And for now that's the only way? Please, don't get me wrong. I'm not complaining, everything is fine! I'm just asking so I'll won't find myself making it tougher and more complex that it actually is. :)

Also, do you have some good tutorials? Channels on youtube to subscribe? Something on the internet which could help me learn Grasshopper? :)

Again, thank you so much for help!
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By leceta
. I would use this referenced polyline to create a roof and the columns in grasshopper all together! but remember that for the time being, you can only create single pane roof in archicad, so its still no very usefull.

for the columns, divide the referenced polyline in order to obtain desired column positions. You have plenty of different way to divide a curve (and a polycurve). By lengths, by curve parameters or by number of divisions... those are basic steps of geometry manipulation in grasshopper.

internet is plenty of grasshopper tutorials. You can check this Primer in PDF format from Modelab,

and also their youtube channel ... kxJgOPk5Jg

designalyze could be also a good place to start

check also jose sanchez´s videos

the best book i know on this topic is from Arturo Tedeschi
By Karol Lozinski
Sorry for not responding this long. I'd like to thank you soo much for all your help! I really appreciate it! I hope there's more people like you. Thank you again!