Parameters

Grasshopper parameters let you select and reference geometry and objects directly from your AutoCAD or Civil 3D drawing. They work like native Rhino parameters — right-click and pick objects from the viewport — and hold a live reference that updates when the source object changes.

Parameters maintain a live reference to AutoCAD objects. When the referenced object changes in the drawing, the Grasshopper definition automatically updates.

Browse the full parameter reference by application:

  • AutoCAD Parameters — curves, points, meshes, solids, hatches, text, dimensions, leaders, and block references.
  • Civil 3D Parameters — alignments, profiles, profile views, corridors, assemblies, parcels, and TIN surfaces.

Selecting Geometry from a drawing

Parameters allow you to pick geometry directly from your drawing, just like selecting geometry from Rhino in standard Grasshopper workflows.

Set One (Single Object Selection)

To select a single object:

  1. Add a parameter to your Grasshopper canvas (e.g. AutoCAD Curve from Params › AutoCAD)
  2. Right-click on the parameter
  3. Select "Set one Curve" (or the appropriate geometry type)
  4. The AutoCAD window will come into focus
  5. Click on the object you want to select in AutoCAD
  6. The selection is complete and the parameter will display the referenced object

The menu option text will match the parameter type: "Set one Curve", "Set one Point", "Set one 3D Solid", etc.

Set Multiple (Multi-Object Selection)

To select multiple objects:

  1. Add a parameter to your Grasshopper canvas
  2. Right-click on the parameter
  3. Select "Set multiple Curves" (or the appropriate geometry type)
  4. The AutoCAD window will come into focus
  5. Click on each object you want to include in the selection
    • You can use window selection (click and drag) to select multiple objects at once
    • You can also click objects individually to add them to the selection
  6. Press Enter when you have finished selecting all objects
  7. All selected objects will be referenced by the parameter

When selecting multiple objects, you must press Enter to confirm and complete the selection. Pressing Escape will cancel the selection.

Selection Filtering

Each parameter type automatically filters the selection to only allow valid object types — if you click an object that doesn't match the parameter type, it won't be selected. See the AutoCAD Parameters and Civil 3D Parameters pages for the selectable object types of each parameter.