Tag: RhinoCommon

Create a list of Rhino geometry within a Grasshopper component using GeometryBase

How to create a generic, mixed list of geometry within a Grasshopper component, and send it to a single output: 

class GeometryBuilder
{
    //constructor
    public GeometryBuilder()
    {
        //...
    }

    //property - declare our geometry list here
    private List<Rhino.Geometry.GeometryBase> geom = new List<Rhino.Geometry.GeometryBase>();
    public List<Rhino.Geometry.GeometryBase> Geom
    { get { return geom; } set { geom = value; }}

    //methods
    public BuildGeometry()
    {
        //add a line
        //lines don't inherit from GeometryBase, so we can't cast it to be in
        // our Geom list, but we can convert it to a NurbsCurve, which does.
        Rhino.Geometry.Line ln = new Line(new Point3d(0,0,0), new Point3d(1,1,0));
        Geom.Add((GeometryBase)(ln.ToNurbsCurve())); 

        //Meshes DO inherit from GeometryBase, so we can add them to Geom directly
        Rhino.Geometry.Mesh msh = someOtherMesh;
        Geom.Add((GeometryBase)msh);

        //Generally, things within Rhino.Geometry that are classes can be cast to GeometryBase.
        //Things which are structs can not, though there is usually a sensible way to convert them.

        //Point3d is a struct, so we can't cast it to GeometryBase.
        //The Rhino Point is a class, and it contains a constructor converting from Point3d
        Rhino.Geometry.Point3d pt3d = new Point3d(5,2,0);
        Rhino.Geometry.Point pt = new Point(pt3d);
        Geom.Add((GeometryBase)pt);
    }
}



class GrasshopperComponent : GH_Component
{
    //constructors etc...
    //...

    //set inputs
    //...

    //set outputs
    protected override void RegisterOutputParams(GH_Component.GH_OutputParamManager pManager)
    {
        //our output is created using the 'AddGeometryParameter' method. Remember to set 'access' to 'list'.
        pManager.AddGeometryParameter("My Geometry","my geom","This is a list of generic geometry", GH_ParamAccess.list);
    }

    protected override void SolveInstance(IGH_DataAccess DA)
    {
        //generate our list of geometry from the class we made
        var GeometryBuilder gb = new GeometryBuilder();
        gb.BuildGeometry();

        //the geometry is now saved within the Geom property of our gb instance of GeometryBuilder.
        //All we need to do now is send the geometry to the Grasshopper output
        DA.SetDataList(0, gb.Geom);
    }
}

Bake and delete objects in Rhino with RhinoCommon

A very basic implementation of baking and deleting objects in Rhino through Grasshopper.

Rhino ObjectTable

Rhino objects are accessed through the object table – a container object which holds information about all objects in a Rhino document. 

Rhino.DocObjects.Tables.ObjectTable ot = Rhino.RhinoDoc.ActiveDoc.Objects;

Add an object

Within the ObjectTable is a range of methods for adding objects. There is a method for each kind of geometry (meshes, lines, points and so on).

For example, to add a line:

ot.AddLine(new Point3d(0, 0, 0), new Point3d(1, 1, 1));

Deleting the most recent object

The Object Table appears to be sorted in order that objects were added, most recent first. So, to delete the most recent object, we need to delete object 0:

//get guid of the most recent object
Guid id = ot.ElementAt(0).Id;

//deletes this object
if(z) ot.Delete(id, true);

Get the number of objects

Unless there’s a better way to do it, the method below works. This returns the number of objects in the object table.

var sf = new Rhino.DocObjects.ObjectEnumeratorSettings();
int count = ot.ObjectCount(sf);

References