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.

| Surface | When to choose | File ext | |---|---|---| | RhinoPython (rhinoscriptsyntax + RhinoCommon) | Default for new scripts. Best ecosystem, readable, full RhinoCommon access. | .py | | RhinoScript (VBScript) | Maintaining legacy .rvb/.vbs files; integrating with VBA/COM. | .rvb, .vbs | | RhinoCommon (C#/.NET) via Script Editor | Performance-critical loops, complex geometry, leveraging .NET libraries. | .cs | | Command macro | Pure sequence of existing Rhino commands; no logic. | toolbar/alias |

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

python
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

python
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

vbscript
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)

python
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

| Symptom | Fix | |---|---| | rs.GetObject returns None immediately | The user pressed Escape, or your filter excludes everything. Re-check rs.filter.* flags. | | “Unable to find script” when running by name | The folder isn’t in Options → Files → Search paths. | | VBScript Type mismatch on coordinates | You passed a 2-element array. Rhino requires 3-element Array(x, y, z). | | Python ImportError: No module named Rhino | You’re running CPython outside Rhino. RhinoCommon is only available in Rhino’s embedded Python (or via rhino3dm for read-only file work). | | Created geometry doesn’t appear | You forgot doc.Views.Redraw(), or rs.EnableRedraw(False) was never re-enabled. | | Undo undoes only the last object of a batch | Wrap the batch in BeginUndoRecord / EndUndoRecord. | | Script works alone but fails as a startup script | Startup runs before any document is open — return early or skip document-dependent work when sc.doc is None. | | rs.Command("...") returns False | The macro string is malformed. Prefix with ! and -, end every prompt with _Enter or a value. | | AttributeError: type object 'RhinoApp' has no attribute 'IsHeadless' | Property added in a later Rhino 8 build. Use getattr(Rhino.RhinoApp, "IsHeadless", None) and guard against None. | | rhinocode script ignores arguments after the script path | rhinocode concatenates extra tokens onto the file URI. Pass data via a temp file or a Rhino dialog instead. See references/macros-and-loading.md. | | Cannot import name <X> inside stdlib (e.g. tempfile, os) when using _-RunPythonScript | Script filename shadows a stdlib module (e.g. random.py shadows random). IronPython 2.7 searches the script directory before stdlib. Rename the script, or remove the import that pulls in the shadowed module and replace it with a direct alternative (e.g. read %TEMP% via os.environ instead of import tempfile). | | SyntaxError: Non-ASCII character '\xe2' ... but no encoding declared | IronPython 2.7 (_-RunPythonScript) hit an em dash or similar character. Add # -*- coding: utf-8 -*- as line 1, or replace the character: em dash --, arrow ->. The same file runs fine under rhinocode (CPython 3), which hides the problem. |

References

• references/rhinoscriptsyntax-cheatsheet.md — most-used rs.* functions by category.
• references/rhinocommon-map.md — which namespace to import for which task.
• references/macros-and-loading.md — command-line macro syntax, LoadScript / RunScript, search paths.
• 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/R_Project_RhinoCommon.htm>
• Example scripts repo: <https://github.com/mcneel/rhino-developer-samples/tree/8/rhinoscript>