# 2.1: Hello Karamba3D

For small scripts the Grasshopper scripting components “C# Script”, “VB Script” or “Python Script” from the **“Maths”** subsection come in handy. A good introduction to scripting in GH can be found in the “Grasshopper Primer”.

All examples which follow can be found in the “[Karamba3D Scripting Examples Github](https://github.com/karamba3d/K3D_Scripting)”-collection that accompanies this manual. When opening them in Grasshopper do not panic if some components turn red. In that case some paths need adaptation (see below).

### Setting up a Script in Rhino6/7

To begin using Karamba3D in a Grasshopper script, follow this example (refer to *“HelloKaramba3D\_RH7.gh”* linked at the bottom of the relevant documentation page):

1. **Add a C# Scripting Component**
   * Place a C# scripting component onto the Grasshopper canvas.
2. **Manage Assemblies**
   * Right-click on the component's icon and select **"Manage Assemblies..."** from the context menu.
3. **Add Karamba3D Assemblies**
   * Under **"Referenced Assemblies,"** click **"Add."**
   * Browse to locate the `karambaCommon.dll` and `karamba.gha` files. These files are typically located in the Rhino Plug-ins folder:\
     `C:\Program Files\Rhino7\Plug-ins\Karamba3D`
   * Ensure you select the appropriate file type:
     * By default, only `.dll` files are visible.
     * Use the drop-down menu in the lower-right corner of the file browser to select **"Grasshopper Assemblies (\*.gha)"** for the `.gha` file.

This setup makes the Karamba3D assemblies accessible to your script, enabling full integration with the plug-in.

### Setting up a Script in Rhino8

The Rhino 8 script editor for C# introduces significant improvements over its predecessor, including built-in debug support. To reference external assemblies, you can explicitly include them in your code.

**Adding Karamba3D Assemblies**

For example, the following lines reference the required Karamba3D assemblies (see *"HelloKaramba3D\_RH8.gh"* at the bottom of this page):

````
#r "C:\Users\<YourUsername>\AppData\Roaming\McNeel\Rhinoceros\packages\8.0\Karamba3D\3.1.40918\KarambaCommon.dll"
#r "C:\Users\<YourUsername>\AppData\Roaming\McNeel\Rhinoceros\packages\8.0\Karamba3D\3.1.40918\Karamba.gha"```
````

* Replace `<YourUsername>` with your specific user name to match your installation path.
* The files are located in the personal folder if Karamba3D was installed via the YAK package manager.

**Convenient Assembly Selection**

For a more user-friendly approach to referencing assemblies:

1. Use the **"Box" button** in the script editor toolbar to open the assembly selection browser.
2. Browse and add the required files directly.

By following these steps, you can integrate Karamba3D assemblies into your Rhino 8 C# scripts with ease.

### Explanation of Code

![Fig. 2.1.1: A minimal K3D-model for retrieving the number of elements, materials and cross sections.](/files/-MXH_8qbowH6_g1a2jDZ)

The source-code to be added inside the C#-component looks like this:

{% code lineNumbers="true" %}

```csharp
    ...
    using Karamba.Models;
    ...
    private void RunScript(object Model_in)
    {
        var model = Model_in as Model;    
        if (model == null) {
            throw new ArgumentException("The input is not of type model!");
      }
      Print("Number of Elements: " + model.elems.Count);
      Print("Number of Materials: " + model.materials.Count);
      Print("Number of Cross sections: " + model.crosecs.Count);
    }
```

{% endcode %}

* **Namespace Inclusion**:\
  The `using` directive (`using Karamba.Models;`) allows shorter, more readable code. For example, instead of typing `Karamba.Models.Model`, you can simply use `Model`.
* **Casting the Input**:
  * `Model_in` is provided as an `object`.
  * To access its properties, it must be cast to the correct type (`Model`).
  * The `if` condition checks if the casting was successful. If not, an `ArgumentException` is thrown to handle invalid inputs (e.g., a vector plugged into the model input).
* **Accessing the Model**:
  * Once cast, the `model` variable holds a reference to the Karamba3D model.
  * The script retrieves data about the model, such as the count of elements, materials, and cross-sections.
* **Output Details**:
  * Use `Print` to display the results in the Grasshopper console.
  * Example outputs:
    * *Number of Elements: 1*
    * *Number of Materials: 1*
    * *Number of Cross sections: 1*

**API Documentation**

For detailed information about the `Model` class and its API, visit the [Karamba3D API Documentation](https://www.karamba3d.com/help/3-1-4), specifically under `Karamba.Models`.

{% file src="/files/szwGosPn3XdS2CKZ2kAE" %}

{% file src="/files/L6LeGItXaWyfdcAOuD2L" %}


---

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