Dynamo Basics: Runs, Previews, and Lacing

Now that most of my posts are focused around Dynamo, I have noticed that many people leaving comments here are trying to troubleshoot a problem that they are having in Dynamo. Even though this might not be the best forum for troubleshooting issues (I would recommend the Dynamo Forum, instead), I have also noticed some simple and recurring issues that multiple people seem to be having. So this post an effort to address some common Dynamo issues and point out some features that you might not know about.

When starting a new Dynamo file, one of the first things to pay attention to is the type of Run you are executing. This is important, particularly if you are using the Select Model Element(s) nodes, because Dynamo will freeze (and likely crash) if you try to use these nodes will running Automatically.


And I use these nodes all the time, so I always switch the Run over to Manual before connecting too many nodes.

As you start creating your definition, there are a few features that can make this process easier. First and foremost, I always have the Background Preview turned on (under View, Background 3D Preview, Available Previews). The Background Preview is extremely helpful and allows you to see what the nodes are doing in the background.


And after running the definition, you can select nodes individually to see exactly what each one is doing. For example, Topography.IntersectionWithPlane is creating points, curves, and nurbsCurves, which all highlight in blue when I select the node.


If you ever want to hide the preview of one or more nodes, right click on the node and uncheck Preview.



This can be particularly useful when working with surfaces and solids, since they can really start to obscure your background preview.

When working in Dynamo through Revit, there is also the option to turn on the Revit Background Preview (also under View, Background 3D Preview, Available Previews). This option will show all of the same data (usually blue dots and lines) but overlaid in your active Revit view.


For some reason the Revit Background Preview is turned on when you first install Dynamo, but I usually turn it off and just use the Background Preview within Dynamo.

And finally, there are two other useful little features that can also be accessed by right clicking on a node: Freeze and Lacing. Freeze is pretty straightforward. Freezing a node disables it and any nodes downstream.


Lacing is slightly more complicated, but the Dynamo Primer has a fairly good explanation in its ‘What’s a List’ section. Essentially, lacing allows you to have simpler definitions, as it can be used instead of List.Map or List.Combine. For example, in order to get SlabShape.Points to pull points from multiple slabs, it must be used with List.Map.


But you can achieve the same thing with only the single node if you change its lacing to Cross Product (note that the lacing symbol has changed to crosses).


Even though I have been using Dynamo for about a year, lacing is something that I learned about relatively recently when I attended a Dutch Dynamo User Group meeting. So if you have to opportunity to attend or even start a Dynamo user group, I would definitely recommend it.


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