BIM Coordinator Program (INT) April 22, 2024

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About building parametric objects with GDL.

Open Source GDL library project

Hi there,

After long thinking on this subject I would like to hit the new Open Source GDL programming project on this forum. The idea to involve GDL developers worldwide to start building new, independent, international, non-commercial library for all. GDL technology has very strong potential and that is very important part why ArchiCAD as a CAD and BIM system is so unique.

Please read the initial statements of this project:

1. The project is running under the GNU GPL licence. It is based on GDL technology, but not limited by it. Any further translations to different programming languages or use in different CAD systems apart of ArchiCAD are welcomed. Additional C++ programming to improve use of the library parts by making special Add-Ons are welcomed too.
2. Anyone, who is taking part of the project, doing it by their free will and free of charge just following the desire to make BIM world better. Donations, investments and grants for developers are discussible and acceptable.
3. The objects must follow all official GDL standards (like GDL white paper) and Graphisoft recommendations. For example - I like to use uppercase in my GDL script for commands (because GDL manual shows all of them in uppercase). But as soon as GS recommends to use lowercase - my opinion or preferences are not valid.
4. Developed library parts must use standard GS variables names to have full compatibility with standard libraries, distributed with official ArchiCAD releases. As well - to use standard GDL subtypes, as soon as introducing new one is not necessary.
5. All library elements must be compatible with Grasshopper - means that most of calculations (that usually happens in Parameter script) shall happens in Master Script, because Grasshopper is not reading Parameter script.
6. Completed library element must be uploaded to web-site for free access of ArchiCAD users worldwide.
7. Any modification to the library part code must be reflected into the versions text file (or log file), provided with the library element.
8. Library part must be truly international - means that they must have multi-language support.
9. Library objects must be not manufacturer-oriented but building element class-oriented with manufacturer support. For example - instead of having ACO drain element - to have rainwater drain element with possibility to choose ACO from manufacturers list.
10. There is no discussions about leadership of the project. Everyone is equal and differs only by experience - strongest are supporting weakest. I will try to manage this project as long as I can, also I'm willing to open some of my personal developments, but I do not pretend to be head of the project (even if this is my idea).
11. Anyone can be involved into any stage of library part development - starting from conceptual graphical schemes and algorithms ending by writing and re-writing actual scripts.
12. Any object must have textual / graphical description how to use it and YouTube video. The links to the manual must be implemented into the object User Interface.
13. Each object must have User Interface.
14. Common global variables names as for example from Add-Ons or MVO objects - matter of community decisions and consultancy with Graphisoft. After the decision is made - this subject is not discussable without serious technical reason.
15. Every GDL object must be written on as lowest ArchiCAD/GDL version as possible - as soon as needed features allowed to use the version.
16. Developing of the new object is starting by introducing your ideas in the post plus hand-drawn (or CAD drawn) sketches and logical (drawn) schemes.
17. This is not PARAM-O project. PARAM-O can be used as a temporary tool, but because of nature of scripts, generated by program automatically, must be reviewed and rewritten by human to achieve better performance and smaller size of script.

Any comments are welcomed.
Not applicable
No doubt it is a very handy method to create polylines. IMO It also should be integrated as a standard construction method for all AC linear elements.
But we all know that in reality roads are not only composed by perfect tangential arcs.
They are. Seriously man, I know that from engineers who are designing roads. The company even been using Microstation, because there creating tangential arcs is very simple.
Roads also in section in most cases are arches, curb stones with foundation work as a bridge (if it's not reinforced concrete panels like in USA).
If road is designed differently - that means this is the road in third world country somewhere in deep province. I've seen the roads in Costa Rica - in banana plantation area. There they even stealing asphalt - so cannot really cover it completely with asphalt - then part of the road gravel. But we are not talking here about such roads, do we?
Should you like to say this not tangential arches?
They are never perfect in real life, then again non of the structure built from our plans are either.
But the optimal design lies in the tangents
Not applicable
Podolsky wrote:
Should you like to say this not tangential arches?
Sure they are.
But IMO this is not the bread-n-butter of most Architects. Irregular road paths are not only a thing for "Third World Countries". Here in Europe we constantly have to deal with old cities with very irregular road grids. And most of the times we have to represent them in 3d in order to do a proper building insertion.
Just because they are existent, doesn't mean they don't need to be modeled, right?
Show me an example of irregular road in Europe. London is full of small old roads, but they all are made from tangential arches. It's needed that transports would be able to turn properly. If you know cities in Europe where roads are made by different rules and where transport is turning differently - I would like to see it.
Not applicable
You can find some here:,-7.3501813,459m/data=!3m1!1e3
The thing is that they will always have an inflexion point with odd angles joints. Specially in connections.
You can't do a sharp turn with a tangential arc. At least to my knowledge.
Ah, of course, Portugal. I thought that it's coming from Spain or Portugal. As I know from one Austrian architect, who is working in Lagos, only 10% of architects in Spain and Portugal are making some sense. Rest even cannot be bothered about waterproof, thermal and acoustic insulation in their projects.
Well, walk on the streets of this town, take some photos of road corners and you will see - that all roads are made from tangential arches. And definitely there you cannot find sharp corners - like 90 degrees. Even in Panama city in Casco Viejo - that is historical Spanish colonial architecture - is like that.
Not applicable
I am talking about cases like this:
This is not really the case. Here doesn't exist even paving. Or you can say - this is only paving. In many cities similar spaces can be closed for cars. I can show examples from Jerusalem Old Town, built originally in time of crusaders, that can look similar, even more complicated. For example the path partially with steps and partially with ramp, because there they have a tractor, that bringing goods to tourists shops in the evenings.

Take a look to the proper road in the same city, where you can drive the car - not just squeeze it somehow between buildings with 3km per hour.

Probably it's necessary to determine what is road for cars, what is paving, what is pedestrian road, what is internal yard and similar. What is main road (high Street), where branches etc.
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