• TechNotes
• Creating custom Library Objects

There are two methods for creating new library parts:

Draw the elements/components

Create a 3D model from Slabs, Walls and other elements / Library Objects, especially using the objects that can be found in the Primitives folder in the ArchiCAD Library. Make sure that one corner of the resulting 3D model is at the absolute (x=0,y=0) origin, because this will be the local origin of that library part. If not, use the Drag command to move your model to the origin. Activate the 3D Window and set the viewpoint the top view. Then save it as an ArchiCAD Object File (.GSM file). You can then choose between Editable GDL Script and Non-editable binary 3D data. Generally select the Editable GDL Script option to be able to modify the 3D script and to add new parameters to the parameter list of the resulting object. If you open such a library part, you will find 3 parameters (A,B,ZZYZX) in the parameter list, an editable 3D script generated by ArchiCAD and a 2D symbol that is a stretchable, vectorial 2D representation of the object. The 3D script contains 3 major parts:

The first contains the comments (In GDL, "!" means that the next characters in that row should not be interpreted by ArchiCAD), the second contains the global variables (see the Appendix in the ArchiCAD GDL Reference Manual for a List of Global Variables) and only the short 3rd part is which creates the 3D representation of the object.

Create different GDL scripts

• Using the GDL Reference Manual, you select the appropriate 2D/3D GDL commands and create your scripts. GDL is close to BASIC or PASCAL programming languages, but generally no programming skills are required to begin experimenting GDL. There are different command families, such as coordinate transformation commands (such as add2/addx), 2D/3D shape commands, mathematical and flow control commands and other non-geometric scripts. The same library part created in GDL has a shorter 3D script and the 2D symbol can be replaced by a simple 2D GDL command in the 2D script.

Pros/Cons.

• When you create library parts from drawn elements, you can create objects without writing GDL scripts. However, the resulting objects will be less parametric: you can control the length/width/height parameters only.
• When you create GDL objects with your own scripts, you can use many parameters of different type and you can even define value lists. You will also be able to modify any component of your object or add a new parameter to it very easily.

CategoryGdl