Hops Component

Hops adds functions to Grasshopper.

Overview Windows

Hops is a component for Grasshopper in Rhino 7 for Windows. Hops adds external functions to Grasshopper. Like other programming languages, functions let you:

  • Simplify complex algorithms by using the same function multiple times.
  • Eliminate duplicate component combinations by placing common combinations in a function.
  • Share Grasshopper documents with other team members.
  • Reference Grasshopper documents across multiple projects.
  • Solve external documents in parallel, potentially speeding up large projects.
  • Run asynchronously on long running calculations without blocking Rhino and Grasshopper interactions.

Hops functions are stored as separate Grasshopper documents. The Hops component will adapt its inputs and outputs to match the function specified. During calculation Hops solves the definition in a separate process, then returns the outputs to the current document.

How to use Hops Windows

Install Hops using the Package Manager in Rhino 7 for Windows:

  1. Install Hops
  2. Or, type PackageManager on the Rhino command line.
  3. Search for “Hops”
  4. Select Hops and then Install

Create a Hops Function

Hops functions are Grasshopper documents with special inputs and outputs.

Hops inputs are Get components. The name of the component is used for the name of the Hops input parameter.

Available Get components are:

Hops outputs are geometry or primitive params in a group named: “RH_OUT:[name]”, where [name] is the name of the output parameter. In this case, the name of the output is “o”.

Use the Hops component

  1. Place the Grasshopper Params Tab > Util Group > Hops component on the canvas.
  2. Right-click the Hops Component, then click Path.
  3. Select a Hops Function.
  4. The component will show the inputs and outputs.
  5. Use the new component like any other Grasshopper component.

Frequently Asked Questions:

Can you nest Hops functions within other functions?

Not at this time.

Does it cost money to use Hops?

Hops is free to use.

Can Hops be used with Grasshopper Player to make commands?

Yes, Hops functions can use Context Bake and Context Print components to create Rhino commands in Grasshopper Player.

Does Hops support parallel processing?

Yes, Hops by default will launch a parallel process for each branch of a datatree input stream.

What input and output types does Hops support? (It supports all common types, ask about other ones if you need them)

Hops passes standard Grasshopper data types (Strings, Numbers, Lines, etc…). For other datatypes such as images or EPW weather files use a string for the file name so that the external function might also read in the same file.

Can plugin components run in Hops Functions?

Yes, all the installed Grasshopper plugins can run within a Hops Function.

Can this be used for extremely long calculations within a function?

Yes, each Hops component has an option to solve asynchronously. The user interface will not be blocked while waiting for a remote process to solve and the definition will be updated when the solve is complete. Hops will wait for all function calls to return before passing the outputs to the downstream components.

Can any existing component be run remotely?

All plugins and existing Grasshopper components can be run as a single component.

Can the code for Hops be used in my C# or Python scripts?

Not at this time. As of now you may embed a custom C# or Python component within a function or before or after a Hops component. https://github.com/mcneel/compute.rhino3d/tree/master/src/compute.components

What is Hops performance?

We have not done extensive benchmarking on this. Any performance improvement comes from solving a complex calculation in parallel; each solution is calculated at the same speed as in Rhino plus the overhead of making the calls to the external function.

How does Hops deal with datatrees?

Standard data-matching rules apply to datatrees. But Hops will spawn a new parallel thread for each branch of a tree.

Hops Settings

Application Settings

The Hops settings control how Hops runs on an application level. It is available through the Grasshopper File pulldown > Preferences.

  • Hops-Compute server URL - List the IP address or URL of any remote machines or Compute servers.
  • Max Concurrent requests - Used to limit the number of active requests in asynchronous situations. This way hops doesn’t make thousands of requests while the original request is being processed.
  • Clear Hops Memory cache - Clears all previously stored solutions from memory.
  • Hide Rhino.Compute Console Window - Hops will solve in the background, but showing the window can be helpful for troubleshooting.
  • Launch Local Rhino.Compute at Start - Use this for remote machines when Compute needs to start before any requests are sent.
  • Child Process Count - Used to limit the number of requests for additional parallel processes. May want to set this to the number of cores available.

Component Settings

Right_click on the Hops component to select any number of options that control how Hops runs.

  • Parallel Computing - Pass each item to a new parallel node if available.
  • Path… - Add the location of the GH function to be solved. This may be a file name, IP address or URL.
  • Show Input: Path - Makes the Path an input on the component so Path can be set through the GH Canvas.
  • Show Input: Enabled - Shows an Enabled input that runs the component based on a True or False Boolean value.
  • Asynchronous - The user interface will not be blocked while waiting for a remote process to solve and the definition will be updated when the solve is complete.
  • Cache In Memory - Previous solutions are stored in memory on the local machine to improve performance if the same inputs were previously calculated.
  • Cache On Server - Previous solutions are stored on the remote server to improve performance. Currently available on Remote Hops services only.

Remote Machine Configuration

By default Hops will use the local computer to solve Grasshopper functions. It is possible to setup remote computers for Hops to call.

Remote machines must be running Windows and have Rhino installed on them.

Configuring a remote machine as a Hops node:

  1. Install Rhino 7.5 or above on the remote computer.
  2. Make sure Rhino runs and is properly licensed.
  3. Get the very latest version of compute.geometry.exe. Either build it yourself or get build from our CI server at https://ci.appveyor.com/project/mcneel/compute-rhino3d/branch/master/artifacts
  4. Run compute.geometry.exe from an Administrator Command Line with an address parameter. For example ‘compute.geometry.exe -address’. is your computer’s address. The port can be any you want; but we tend to use values above 6000.
  5. Note the IP address of the remote machine.

To test the status of the remote machine:

  1. On another computer, open a browser and enter Use the IP and port numbers entered in the above steps.

If you get the word “healthy” back, you are all set up.

Setting up Hops to communicate with the remote machine

In the Grasshopper preferences > Solver > Hops - Compute Server URLs enter the IP and port of each remote computer. For the above example enter:

Video Tutorial:

Calling a CPython Server

Use Hops to call into CPython. Some advantages of this component:

  1. Call into CPython libraries including Numpy and SciPy
  2. Use some of the newest libraries available for CPython such as TensorFlow.
  3. Create re-usable functions and parallel processing.
  4. Supports real debugging modes including breakpoints.
  5. Full support of Visual Studio Code.
  6. Other applications and services that support a Python API can also use the libraries included here.
  7. The Hops component attempts to detect when inputs and outputs have changed on a server and will rebuild itself.

Getting started with CPython in Grasshopper

This Python module helps you create Python (specifically CPython) functions and use them inside your Grasshopper scripts using the new Hops components.


  1. Rhino 7.4 or newer.
  2. CPython 3.8 or above
  3. Hops Component for Grasshopper
  4. Visual Studio Code highly recommended

Video Tutorial:

This module can use its built-in default HTTP server to serve the functions as Grasshopper components, or act as a middleware to a Flask app. It can also work alongside Rhino.Inside.CPython to give full access to the RhinoCommon API.

Shortcut to a single Grasshopper Component

Hops can call into a single Grasshopper component using the remote instance to solve it. This can be helpful if many parallel instances of the component would speed up a definition. Simply enter the name of the component.

Using Remote Services

Hops may call into other applications for results. What is required on the other application is Hops protocol awareness. An example of calling into a remote service is the Hops component calling into CPython. These libraries can also be used in the Python API of other applications and services. See the CPython Example above. For details see the ReadMe on GH Hops CPython project.