Rhino 3D Scripting Skill

Write production-quality scripts for Rhinoceros 3D. Covers the three scripting surfaces (RhinoScript/VBScript, RhinoPython, direct RhinoCommon .NET) and the Rhino 8+ Script Editor.

When to Use This Skill

• User asks to write, edit, or debug a .rvb, .vbs, or .py Rhino script
• User wants a Rhino command macro or wants to automate a sequence of Rhino commands
• User wants to manipulate geometry, layers, blocks, materials, viewports, or annotations from code
• User mentions rhinoscriptsyntax, scriptcontext, RhinoCommon, Rhino.Geometry, RhinoDoc, or the Script Editor
• User wants to pick objects, prompt for input, or build a small UI inside Rhino
• User asks how to load, run, or distribute a script (startup scripts, aliases, toolbar buttons)

Choosing a Scripting Surface

Pick the surface based on the task, not preference. Recommend Python by default for new work.

A macro is not a script — it is a string of command-line input (e.g. ! -Line 0,0,0 10,0,0 Enter). Use a script the moment you need a variable, loop, or conditional.

Prerequisites

• Rhino 7 or later (Rhino 8 strongly recommended — unified Script Editor supports Python 3, VB, and C# in one window).
• Script Editor: type ScriptEditor (Rhino 8) or EditPythonScript / _EditScript (older).
• Run a saved file from the command line with -RunPythonScript or LoadScript + _RunScript.

Core Patterns

Python: minimal scaffold

import rhinoscriptsyntax as rs
import scriptcontext as sc
import Rhino

def main():
    obj_id = rs.GetObject("Select a curve", filter=rs.filter.curve, preselect=True)
    if not obj_id:
        return
    length = rs.CurveLength(obj_id)
    print("Length: {0:.4f}".format(length))

if __name__ == "__main__":
    main()

Python: working with RhinoCommon directly

import Rhino
import scriptcontext as sc

doc = sc.doc  # Rhino.RhinoDoc.ActiveDoc
tol = doc.ModelAbsoluteTolerance

circle = Rhino.Geometry.Circle(Rhino.Geometry.Point3d(0, 0, 0), 5.0)
curve_id = doc.Objects.AddCircle(circle)
doc.Views.Redraw()

VBScript: minimal scaffold

Option Explicit

Call Main()

Sub Main()
    Dim strObject
    strObject = Rhino.GetObject("Select a curve", 4)  ' 4 = curve filter
    If IsNull(strObject) Then Exit Sub
    Rhino.Print "Length: " & Rhino.CurveLength(strObject)
End Sub

Picking objects with a custom filter (Python, RhinoCommon)

import Rhino
import scriptcontext as sc

go = Rhino.Input.Custom.GetObject()
go.SetCommandPrompt("Select breps")
go.GeometryFilter = Rhino.DocObjects.ObjectType.Brep
go.SubObjectSelect = False
go.GetMultiple(1, 0)
if go.CommandResult() != Rhino.Commands.Result.Success:
    pass
else:
    ids = [go.Object(i).ObjectId for i in range(go.ObjectCount)]

Step-by-Step Workflows

Bulk-modify many objects fast

1. Disable redraw: rs.EnableRedraw(False).
2. Wrap mutations in a single undo record: undo = doc.BeginUndoRecord("My Op") … doc.EndUndoRecord(undo).
3. Use RhinoCommon directly inside the loop (skip rhinoscriptsyntax overhead).
4. Re-enable redraw and call doc.Views.Redraw() in a try/finally so a crash never leaves the viewport frozen.

Distribute a script to a teammate

1. Save the .py / .rvb somewhere on disk.
2. Add the folder to Options → Files → Search paths so Rhino can find it by name.
3. Create a toolbar button or alias whose macro is:

- Python: ! -RunPythonScript "MyScript.py" - RhinoScript: ! -LoadScript "MyScript.rvb" _-RunScript MySubName

1. The leading ! cancels any running command; - runs the command in script (no-dialog) mode.

Run code at Rhino startup

1. Place a .rvb/.py in a search path.
2. Tools → Options → RhinoScript (or Python) → add to Startup list. The file executes once per session.

Gotchas

• rhinoscriptsyntax returns GUIDs, RhinoCommon returns objects. Mixing them is fine, but doc.Objects.Find(guid) is the bridge from a rs.* id to a RhinoObject.
• Coordinates differ by surface. Python uses (x, y, z) tuples or Rhino.Geometry.Point3d; VBScript uses 3-element Array(x, y, z). Never pass a Python list to a VBScript helper through COM.
• Option Explicit is off by default in VBScript. Typos silently create new variables. Always add Option Explicit at the top of .rvb files.
• VBScript has no block scope. All Dims inside a Sub are hoisted to the top of the procedure. Loop counters leak.
• Nothing, Empty, and Null are different in VBScript. Use IsNull for Rhino.GetObject failure, IsEmpty for uninitialized Variant, Is Nothing for object refs.
• Parentheses change calling semantics in VBScript. Call Foo(a, b) and Foo a, b are valid; Foo(a, b) (no Call, with parens) is not a call to a Sub — it’s a syntax error for multi-arg subs and a forced ByVal for single-arg.
• Tolerance is per-document. Always read doc.ModelAbsoluteTolerance rather than hardcoding 0.001; users work in mm, m, inches, etc.
• Long loops should poll Rhino.RhinoApp.EscapeKeyPressed so the user can cancel. Otherwise Rhino appears frozen.
• GUID strings vs System.Guid. rhinoscriptsyntax accepts either; RhinoCommon wants System.Guid. Convert with System.Guid(str_id) if needed.
• Don’t call doc.Views.Redraw() inside a tight loop. Toggle redraw once outside the loop.
• .rvb is just .vbs renamed with a Rhino-specific extension so Rhino’s LoadScript recognizes it. Same VBScript engine.
• Rhino.RhinoApp.IsHeadless may not exist on older Rhino 8 builds. Use getattr(Rhino.RhinoApp, "IsHeadless", None) and check for None before using. Fall back to a heuristic (e.g. sc.doc.Views.Count == 0) or assume GUI present.
• RhinoMath is at Rhino.RhinoMath, not Rhino.DocObjects.RhinoMath. Accessing Rhino.DocObjects.RhinoMath raises AttributeError.
• doc.Objects.AddBrep() returns System.Guid.Empty on failure. In Rhino 8 CPython the System namespace may not be directly importable; check the return value as a string: str(obj_id) == "00000000-0000-0000-0000-000000000000".
• rhinoscriptsyntax has no type stubs. Static analysers (Pylance/Pyright) flag import rhinoscriptsyntax as rs as unresolvable. Suppress with # type: ignore on the import line; the module is always available at Rhino runtime.
• Never name a script after a Python standard-library module (e.g. random.py, math.py, os.py). IronPython 2.7 (_-RunPythonScript) resolves the script directory before stdlib, so any import random inside the stdlib (e.g. tempfile imports random internally) will find your file instead and fail with Cannot import name <X>. CPython 3 (rhinocode) is unaffected because it resolves stdlib first. Rename the script or avoid importing modules that pull in the shadowed name.
• Em dashes and other non-ASCII characters silently break _-RunPythonScript (IronPython 2.7). rhinocode script uses CPython 3 (UTF-8 by default) so the same file works there, making the failure non-obvious. IronPython 2.7 raises SyntaxError: Non-ASCII character '\xe2' at the first offending byte. The most common culprit is the em dash (-- auto-converted to -- by many editors). Add # -- coding: utf-8 -- as line 1 of every script that must run under both runtimes, and replace typographic characters with ASCII equivalents: em dash --, arrow ->, multiplication x.

Troubleshooting

References

• [references/rhinoscriptsyntax-cheatsheet.md](references/rhinoscriptsyntax-cheatsheet.md) — most-used rs.* functions by category.
• [references/rhinocommon-map.md](references/rhinocommon-map.md) — which namespace to import for which task.
• [references/macros-and-loading.md](references/macros-and-loading.md) — command-line macro syntax, LoadScript / RunScript, search paths.
• [references/vbscript-quirks.md](references/vbscript-quirks.md) — VBScript-only traps relevant to RhinoScript.

Upstream docs

• RhinoScript landing: <https://docs.mcneel.com/rhino/8/help/en-us/information/rhinoscripting.htm>;
• Developer hub: <https://developer.rhino3d.com/>;
• RhinoCommon API index: <https://mcneel.github.io/rhinocommon-api-docs/api/RhinoCommon/html/RProjectRhinoCommon.htm>
• Example scripts repo: <https://github.com/mcneel/rhino-developer-samples/tree/8/rhinoscript>;