Grasshopper

Open Grasshopper inside AutoCAD and watch geometry flow live into the viewport.

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Opening Grasshopper

Grasshopper is Rhino's visual programming environment, and it runs in AutoCAD as well. Visual programming means you build logic by placing components on a canvas and wiring them together rather than writing code. Each component performs an operation, the wires carry data from one to the next, and the result updates automatically as you change inputs. It lets you define geometry and data parametrically driven by adjustable values, so you can explore many variations without rebuilding anything by hand.

If you've used Dynamo in Civil 3D or Revit, Grasshopper will feel familiar: both are node-based, parametric, data-flow tools for generating and manipulating geometry. Grasshopper is Rhino's equivalent, and Rhino.Inside.AutoCAD brings it directly into the AutoCAD environment so you can drive AutoCAD geometry with it.

1. In AutoCAD, run the GRASSHOPPER command (type it, or use the toolbar button).
2. Grasshopper needs Rhino running underneath it, so RiA starts Rhino behind the scenes for you.
3. The familiar Grasshopper canvas appears.

Further reading: How RiA starts Rhino for Grasshopper

What happens depends on whether Rhino is already going:

• If Rhino isn't running yet, it starts in headless mode — the engine runs in the background with no Rhino window shown — and Grasshopper opens on top of it.
• If Rhino is already running (for example, you launched it with RHINO earlier), Grasshopper simply opens against that existing instance.

Further reading: Closing Rhino and Grasshopper

Closing the Rhino window doesn't close Rhino. If you have the Rhino window open and close it, the window is only hidden — the Rhino engine keeps running in the background so Grasshopper and the AutoCAD link continue to work. To bring the window back, run RHINO again.

Closing the Grasshopper window doesn't close Grasshopper either. It only hides the canvas; any open definitions stay loaded and continue to compute. To actually close a definition:

1. Click the definition's name in the top-right of the Grasshopper window.
2. A list of all open definitions appears, each with a red ✕.
3. Click the red ✕ next to a definition to close it.

Grasshopper open inside the AutoCAD session.

Orient yourself to the canvas:

• The standard Grasshopper component tabs are all present.
• A dedicated AutoCAD tab is added by Rhino.Inside.AutoCAD — this is where AutoCAD-specific components live, including the baking component you'll use in Baking.
• Under Grasshopper's Params tab you'll also find an AutoCAD group. These are the parameter components used to specify and reference AutoCAD geometry and data (curves, hatches, blocks, and so on) inside your definition. You'll use these parameters to pull existing drawing objects into a definition — see Bringing an AutoCAD object into Grasshopper for a worked hatch example.
• The Grasshopper solver is enabled by default. Each Grasshopper definition is a live document, and any change you make to it — adding or deleting a component, rewiring a connection, or dragging a slider — automatically triggers that document to recompute. The affected part of the definition re-solves immediately, and because of the live link the new result is pushed straight to the AutoCAD viewport. You don't run a build step; editing the definition is what drives the recompute.

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With the canvas open, the next step is to build a definition and watch it preview live in the AutoCAD viewport. Continue to Preview.