Dynamo - Plane using 3 Points

This is the second method of creating a Plane shown by Nathan Miller, ported into Revit Dynamo:

Again, it’s fairly simple. The only tricky bit is that Dynamo doesn’t expose the Revit API call NewPlane(CurveArray), so I’ve made a Python-based user node to wrap that functionality.

The three points in this example are made with my XYZ… user nodes, and fed into the pair of Line nodes to create two geometry lines. Note the order of the points: The end of one line has to connect to the start of the next. The List node puts the two lines into a list to feed into the Plane by Curves user node. Again, the Transaction node is there because Dynamo asked for it, and the Watch is there so you can see that something happens.

The Plane by Curves user node is simply a wrapper for a bit of Python:

Here is the Python script:

The input from Dynamo is a list of curves or lines. But you cannot use that list of curves as input to NewPlane. You have to unpack the list and put the curves into a Revit API CurveArray object, because that is the type of input that NewPlane(CurveArray) expects. So the “carray =…” line creates the empty CurveArray, and the “for i in range…” lines append each curve to the CurveArray.

This shows the power of the Python node for extending Dynamo. The NewPlane(CurveArray) call isn’t exposed in base Dynamo, but it is fairly easy to add with a Python-based user node. I’m no Python expert (and this node owes a lot to Nathan Miller’s original RevitPythonShell script), but it didn’t take too much trial-and-error to get it working.

And here’s the source: Link to Dynamo Definition PG 2.2 Sketch Plane 3 Points.