Visual Studio and C# : Line as Geometry Base

Hi,

I would like to sort objects by type. (Sorting only meshes and lines)

It works in c# component in grasshopper, when type hint is GeometryBase.

But when I try to input these objects in visual studio:

pManager.AddGeometryParameter("Geo", "G", "GeometryBase", GH_ParamAccess.list);

I get an error already at input part of code:

1. Invalid cast: Line » GeometryBase

I attached printscreens, gh, and code from visual studio.

Could you please give me an advice how to solve it?

Attachments:

Replies to This Discussion

Permalink Reply by David Rutten on March 12, 2016 at 4:13pm

Rhino.Geometry.Line is a high-performance struct that does not partake in any of the interface/class hierarchies in RhinoCommon. If you want a line that is a type of GeometryBase you need to create a LineCurve class instead.

Permalink Reply by Petras Vestartas on March 12, 2016 at 4:22pm

I thought to input a list System.Objects (nulls,meshes, lines) then.

It was just interested that C# in grasshopper converts line to lineCurve using type hint, but visual studio not.

But how to check the type of the object then? As with GeometryBase I just use ObjectType function.

Permalink Reply by Petras Vestartas on March 12, 2016 at 4:40pm

This seems to work:

    String t = G.GetType().ToString();
    if(t == "Rhino.Geometry.Line"){
     ...
    }

Permalink Reply by Long Nguyen on March 14, 2016 at 9:59am

A more efficient way is to compare the Type objects directly rather than their string presentations. This can be beneficial if you are processing a lot of data. To get a Type object you can use the typeof operator as follow

if (G.GetType() == typeof(Rhino.Geometry.Line))

...

Permalink Reply by David Rutten on March 14, 2016 at 1:15pm

I much prefer the is and as keywords (though as won't work on structs, you'll need to cast in that case):

object someGeometry = ...;

if (someGeometry is Mesh)

Mesh mesh = someGeometry as Mesh;

else if (someGeometry is Line)

Line line = (Line)someGeometry;

The as keyword never throws exceptions and instead assigns null to the target is the conversion is not possible, which is why it cannot be used on structs.

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