DataTrees with multiple data types

Grasshopper Developer
1

Pardon me if my google-fu is weak but I couldn’t find this anywhere.

I mostly understand how to work with Datatrees in a component I’m writing in C#. However, our application (which I’m trying to replace bit by bit with custom components) utilizes mixed type Datatrees. For example, we have a tree where each branch contains a point in the first entry, and int then the second, a vector in the third, etc. How do I create such a beast in C#? Is there some sort of multi-templating paradigm I’m not aware of?

2

If using the SDK, rather than C# components, you’ll need to use GH_Structure instead of DataTree. GH_Structure is also a generic type which has a constraint in that T must be a type of IGH_Goo. Thus, if you’re going to store more than one type of data inside a GH_Structure, you should declare it to be of type GH_Structure<IGH_Goo>. Since GH_Point, GH_Integer, etc. all implement IGH_Goo this will work.

3

Thank you so much! I’m sure I’ll have more questions but I seem to have this working as I would expect.

4

More questions from this guy :slight_smile:

I am writing code to populate a data tree. The following does exactly what I want and expect, populates the first entry in each branch with a point constructed from a list of doubles xyz. So my question is, simply, am I doing anything that will get me in trouble memory-wise? Also, it seems silly to jump through a Point3D to get to GH_Point but I couldn’t see a way to directly populate the GH_Point.

Thanks.

GH_Structure<IGH_Goo> output = new GH_Structure<IGH_Goo>();
for (int i = 0; i < totalLength; i++)
      {
        int whichPoint = path[i];
        Point3d p0 = new Point3d();
        GH_Point ghPoint = new GH_Point();
        p0.X = xyz[whichPoint][0];
        p0.Y = xyz[whichPoint][1];
        p0.Z = xyz[whichPoint][2];
        ghPoint.Value = p0;
        output.Insert(ghPoint.Duplicate(), new GH_Path(i), 0);
      }
5

Don’t see anything wrong. You don’t have to worry about variables inside functions or loops, the compiler is pretty good about optimising that sort of stuff. Do note that Point3d is a ValueType, so you don’t need to invoke its constructor. Or, if you do, you may as well provide the xyz coordinates directly.

You don’t have to duplicate the GH_Point btw. It’s known only to your loop where it goes out of scope during the next iteration.

GH_Structure<IGH_Goo> output = new GH_Structure<IGH_Goo>();
for (int i = 0; i < totalLength; i++)
{
  int index = path[i];
  GH_Path pointPath = new GH_Path(index);
  Point3d point = new Point3d(
    xyz[index][0], 
    xyz[index][1], 
    xyz[index][2]);
  GH_Point ghPoint = new GH_Point(point);
  output.Append(ghPoint, pointPath); // I just realised you may need Insert() if you're populating this tree from various loops in reverse order.
}
6

Thanks again!