Preview

The preview is how Rhino and Grasshopper geometry becomes visible inside the AutoCAD viewport. This is the core behaviour to understand.

The Rhino preview

See geometry in the AutoCAD viewport

  1. With Rhino open, create some simple geometry in Rhino — for example, draw a Box or a Sphere.
  2. Switch to AutoCAD. The Rhino geometry is drawn in the AutoCAD viewport as a preview, overlaid on your drawing.
  3. Can't see it? You may need to zoom in or out in AutoCAD to bring the preview into view — type ZOOM ▸ Extents (or double-click the mouse wheel) so the view frames everything, including the new geometry.

Geometry modelled in Rhino, previewed live inside AutoCAD.

Notice: the preview is not in your drawing

Try to click the Rhino geometry in AutoCAD — you can't. It doesn't highlight, you can't grip-edit it, and it won't appear in a selection window. That's because the preview is a transient overlay, not an AutoCAD object.

Now do the reverse — select the geometry in Rhino and watch the AutoCAD viewport: the preview changes to the selection colour. This is the live link at work: AutoCAD is mirroring Rhino's selection state, even though the geometry only "lives" in Rhino.

Key concept — the preview is transient. Preview geometry is drawn live in the viewport but is not part of the AutoCAD drawing database. It can't be selected or manipulated in AutoCAD, it won't be saved with the .dwg, and it won't appear in selections, schedules, or exports. To turn it into a real, editable AutoCAD object you must bake it (see Baking).

Toggle preview visibility

You don't always want the Rhino preview on top of your drawing. Use the toggle to show or hide it:

  • Run TOGGLE_RHINO_PREVIEW (or click its toolbar button) to switch the Rhino preview on/off. The toolbar icon updates to reflect the current state.

The same view with TOGGLE_RHINO_PREVIEW used to hide the Rhino preview.

Practise toggling the preview on and off and orbiting the AutoCAD view. Getting comfortable with what the preview is — a live, non-saved overlay — is the foundation for everything that follows.

The Grasshopper preview

Grasshopper geometry previews the same way, flowing from Grasshopper → Rhino → the AutoCAD viewport, live.

Preview a simple definition

  1. Place a Circle component. On the Grasshopper ribbon, open the Curves tab, find the Primitives group, and click the Circle button. Then click once on an empty spot on the canvas to drop the component there.
  2. Add a Number Slider for the radius, using either method:
    • From the menus: Params ▸ Input ▸ Slider, then place it on the canvas; or
    • Double-click an empty spot on the canvas and type a number — for example 100 — to instantly create a slider that runs from 0 to 100.
  3. Connect the slider to the radius. Drag from the semicircular output node on the right-hand side of the Number Slider and drop it onto the semicircular input node labelled Radius on the Circle component.
  4. With the Circle's preview on (the default), the resulting geometry appears as a preview in the AutoCAD viewport, exactly like the Rhino preview. (Any component that outputs geometry will do — Circle is just a convenient example.)
  5. Drag the slider. The geometry updates live in AutoCAD as Grasshopper recomputes.

A circle defined in Grasshopper, previewed live in the AutoCAD viewport.

Same rule as before. The Grasshopper preview is also transient — it's drawn in the viewport but isn't in the AutoCAD database until you bake it.

Control the Grasshopper preview

Rhino.Inside.AutoCAD gives you display modes for the Grasshopper preview, mirroring Grasshopper's own preview settings:

CommandEffect
GRASSHOPPER_PREVIEW_SHADEDShow Grasshopper geometry shaded (with wireframe)
GRASSHOPPER_PREVIEW_WIREFRAMEShow Grasshopper geometry as wireframe only
GRASSHOPPER_PREVIEW_OFFHide the Grasshopper preview

Seeing wireframe when you asked for shaded? Check the AutoCAD visual style. Shaded previews are drawn only in views that support shading — the default 2D Wireframe view doesn't, so the preview falls back to wireframe there. Switch the viewport to a shaded visual style (VSCURRENT ▸ Shaded, Conceptual, or Realistic, or the 3D Modeling workspace) and GRASSHOPPER_PREVIEW_SHADED displays as expected.

Two more commands control the solver itself:

CommandEffect
GRASSHOPPER_RECOMPUTEForce the definition to recompute its solution
GRASSHOPPER_TOGGLE_SOLVEREnable / disable the Grasshopper solver

Try turning the wireframe preview off and on. Confirm that moving the slider still updates the AutoCAD preview while the solver is enabled — and that it stops updating once you toggle the solver off.

Preview colours

The colours previews are drawn in are yours to choose. Rhino previews, Grasshopper previews and selected previews can each be set to any AutoCAD Color Index from 1 to 255 on the Settings tab of the support dialog, and changes are applied to the previews already on screen straight away — no re-run and no restart.

The defaults are the colours the plug-in has always used, so nothing changes appearance until you choose otherwise. See Settings › Preview colours for the full list and the defaults.

When your definition is producing the geometry you want, the next step is to commit it into the drawing. Continue to Baking.