--- title: "McNeel Rhinoceros (Rhino 8) AI Skill Guide (GPT & Codex)" description: "Comprehensive operational skill specification for OpenAI GPT and Codex to automate, script, troubleshoot, and optimize McNeel Rhinoceros (Rhino 8), RhinoCommon API, Grasshopper Hops, and Rhino.Compute." category: "NURBS Surface Modeling & Computational Design" tags: ["rhino", "rhinocommon", "rhino-compute", "grasshopper-hops", "gpt-codex", "computational-geometry"] --- # McNeel Rhinoceros (Rhino 8) AI Skill Guide (GPT & Codex) ## Overview & Engine Architecture McNeel Rhinoceros (Rhino 8) provides an extensive OpenNURBS C++ geometric modeling core accessible via **RhinoCommon (.NET / CPython 3)** and **Rhino.Compute REST APIs**. GPT/Codex acts as a Principal Computational Geometry Developer and Pipeline Architect, delivering **RhinoCommon algorithms**, **Grasshopper Hops microservices**, **headless Brep generators**, and **automated STEP/3DM file converters**. ### Pipeline Architecture & Developer Layer ``` ┌─────────────────────────────────────────────────────────────┐ │ Rhino Developer Ecosystem │ │ │ │ OpenNURBS Geometry Core │ │ ├── `Rhino.Geometry.Brep`, `NurbsSurface`, `Curve`, `Mesh` │ │ ├── Spatial Search Structures (RTree, KDTree, Octree) │ │ └── Intersect, Boolean, Fillet, and Offset Math Kernels │ │ │ │ Scripting & Distributed Services │ │ ├── Rhino 8 CPython 3.9 Integration (`import Rhino`) │ │ ├── Grasshopper Hops (Remote C# / Python Node Execution) │ │ └── Rhino.Compute (Headless Geometry Server via HTTP REST) │ └─────────────────────────────────────────────────────────────┘ ``` --- ## Operational Capabilities & Agent Directives 1. **Pure RhinoCommon Python Scripting**: Author high-speed algorithmic geometry scripts using `Rhino.Geometry` without GUI dependencies, suitable for standalone execution via Rhino.Inside or CPython 3. 2. **Grasshopper Hops Microservice Integration**: Author stateless geometry functions using `ghhops-server` (Flask/FastAPI) to expose Python math and machine learning solvers directly to Grasshopper canvas nodes. 3. **Spatial Search & Collision Optimization**: Leverage `Rhino.Geometry.RTree` for lightning-fast bounding box and point-cloud distance queries ($O(\log N)$ complexity). 4. **Automated Conversion & Export Pipelines**: Build command-line converters for 3DM, STEP, IGES, OBJ, and glTF asset management. --- ## Production Python Automation: Standalone RhinoCommon Procedural Truss Generator Run this script in the Rhino 8 Python 3 Editor (`import Rhino.Geometry as rg`) to generate a parametric 3D space truss with solid pipe struts and spherical joint nodes: ```python """ Rhino 8 Automation: Procedural 3D Space Truss Generator Pure RhinoCommon implementation utilizing Brep and Mesh primitives. """ import math import Rhino import Rhino.Geometry as rg import scriptcontext as sc def create_space_truss(length=50.0, width=20.0, height=10.0, bays=5, strut_radius=0.5, joint_radius=1.2): doc = sc.doc dx = length / bays bottom_nodes = [] top_nodes = [] struts = [] # 1. Generate Node Coordinates for i in range(bays + 1): x = i * dx bottom_nodes.append(rg.Point3d(x, 0, 0)) bottom_nodes.append(rg.Point3d(x, width, 0)) if i < bays: top_nodes.append(rg.Point3d(x + dx/2, width/2, height)) # 2. Add Spherical Joint Nodes to Document for pt in bottom_nodes + top_nodes: sphere = rg.Sphere(pt, joint_radius) doc.Objects.AddSphere(sphere) # 3. Connect Strut Curves lines = [] # Bottom Longitudinal Chords for i in range(bays): lines.append(rg.Line(bottom_nodes[2*i], bottom_nodes[2*(i+1)])) lines.append(rg.Line(bottom_nodes[2*i+1], bottom_nodes[2*(i+1)+1])) lines.append(rg.Line(bottom_nodes[2*i], bottom_nodes[2*i+1])) # Top Longitudinal Chords for i in range(len(top_nodes) - 1): lines.append(rg.Line(top_nodes[i], top_nodes[i+1])) # Diagonal Web Struts for i in range(bays): top_pt = top_nodes[i] lines.append(rg.Line(bottom_nodes[2*i], top_pt)) lines.append(rg.Line(bottom_nodes[2*i+1], top_pt)) lines.append(rg.Line(bottom_nodes[2*(i+1)], top_pt)) lines.append(rg.Line(bottom_nodes[2*(i+1)+1], top_pt)) # 4. Generate Solid Cylindrical Brep Struts for line in lines: crv = line.ToNurbsCurve() pipe_breps = rg.Brep.CreatePipe( crv, strut_radius, False, rg.PipeCapMode.Flat, True, doc.ModelAbsoluteTolerance, doc.ModelAngleToleranceRadians ) if pipe_breps: for b in pipe_breps: doc.Objects.AddBrep(b) doc.Views.Redraw() print(f"Successfully generated space truss: {len(lines)} struts and {len(bottom_nodes)+len(top_nodes)} joints.") if __name__ == "__main__": create_space_truss() ``` --- ## Technical Troubleshooting Matrix | Issue & Failure Signature | Root Cause Analysis | Diagnostic & Resolution Pathway | | :--- | :--- | :--- | | **`Rhino.Geometry.Brep.CreateBooleanUnion` Returns Null** | Input Breps contain non-manifold edges, micro-gaps, or coplanar coincident faces within document tolerance. | 1. Verify `brep.IsValid` and `brep.IsSolid` for every input Brep.
2. Call `brep.Repair(doc.ModelAbsoluteTolerance)`.
3. Offset coincident faces by $0.005\text{ mm}$ before unioning. | | **Grasshopper Hops Component Shows Connection Refused** | The backend Python `ghhops-server` HTTP daemon is not running on localhost or port 5000 is occupied. | 1. In terminal, run `python app.py` (verify server is listening on `http://127.0.0.1:5000`).
2. In Grasshopper Hops settings, verify Hops URL path.
3. Check firewall rules for TCP port 5000. | | **Python Script Fails with `ImportError: No module named numpy`** | Rhino 8 CPython 3 runtime does not have the target pip wheel installed in its internal virtual environment. | 1. In Rhino 8 Script Editor, open *Tools $\rightarrow$ Python 3 $\rightarrow$ Manage Packages*.
2. Search for `numpy` and click **Install**.
3. Or run `# r: numpy` at the top of your Python script for auto-install. | | **RTree Spatial Query Returns Duplicate Hit Points** | Bounding box margin in `RTree.Search` is too wide, matching multiple neighboring leaf nodes. | Filter query results using `Point3d.DistanceTo()` against a strict threshold distance after the broad-phase RTree query. | --- ## Command Line Syntax & Batch Processing ```bash # Windows CLI: Execute Rhino Python Script in Background "C:\Program Files\Rhino 8\System\Rhino.exe" /nosplash /runscript="-_RunPythonScript C:\Pipeline\truss_gen.py" # Launch Grasshopper Hops HTTP Microservice python -m ghhops_server --port 5000 --reload ``` ### Essential File Locations - **Windows Python 3 Packages**: `%USERPROFILE%\.rhinocode\py39-rh8\site-packages` - **Windows Grasshopper Settings**: `%APPDATA%\Grasshopper` - **macOS Python 3 Packages**: `~/.rhinocode/py39-rh8/site-packages` --- ## Agent Operational Directive > **MANDATORY**: When scripting RhinoCommon operations, validate all Breps using `brep.IsValid` and `brep.IsSolid` before passing them to Boolean or Fillet math engines. In Rhino 8, use `# r: ` to declare Python package dependencies.