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About building parametric objects with GDL.

Object conversions

In an attempt to reduce the amount of coding necessary for a complexly shaped object in GDL I decided to create the item using MCAD software and saving it as a .3ds file. I then imported the .3dsl file into AC (26) and save as a GDL file. I next opened the file in the GDL editor and the part. To my amazement the file wasn't anything like I expected and the majority of the code was descriptions of polygons, surfaces and lines of which there were thousands. The item in this case was a wheel with 2 flat sides and the circular surface was "U" shaped like a roller coaster wheel. From what little I have learned about scripting a GDL the file could have been much smaller by using GDL keywords and such. My question is, why doesn't the converter create the file using those keywords and such instead of thousands of surfaces and lines, etc.? I considered the wheel as a relatively simple part but what if the item has lots of curved surfaces and they aren't symetrical or similar. As an example, what if an edge has a radius that starts as one size and varies over the length down to no radius? It would be nicer if the conversion software could generate smaller file sizes. I'm just getting ready to create a complex item and while I've coded in BASIC which is almost the same as GDL it has been a while and I was hoping I didn't have to describe the item using three basic elements (sphere, extrusion and cylinder). Are there any Short-cuts? Thanks


Accepted Solutions

Thanks guys. It's obvious that there isn't any short cuts and I have much learning to do. I am sure I will have more questions so I appreciate the help from everyone.

Best Regards

View solution in original post

Barry Kelly

@wile e coyote genius wrote:

Are there any Short-cuts? Thanks


As far as Archicad is concerned, you are dealing with surfaces from the other software.

It has no way to know that there is a PRISM, or a SPHERE or any other GDL shape.


If you want clean GDL scripts, you have to script it in GDL language yourself.

Or Param-o will produce GDL style scripts as well as far as I know.


But converting from any other source, you are just dealing with surfaces.



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The amount of math required to translate raw polydata into AC commands would be insane.  Between checking triangles to see if they are coplanar to checking angles when they are not, from comparing adjacent coplanar nodes to see if they form a "curve" then checking if they can fit to a circle to checking their tangents and intersections to see if they are continuous, etc. It would be highly impractical. If the said outputted data was in a language like C, then you might have a chance, but no modelling program would be outputting a model data in a language like that... Max files might contain spline data which would help, but I am pretty sure 3ds files are pure triangles, so importing it is like taking a paper mache mold of a clay model, while what you are desiring is an instruction manual that you can translate for AC to read.


Have you tried the Rhino/Grasshopper plugin?




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Thanks guys. It's obvious that there isn't any short cuts and I have much learning to do. I am sure I will have more questions so I appreciate the help from everyone.

Best Regards

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