Rhino 3D Tip: Rhino to Real‑Time Engines: Clean Models, Optimized Meshes, Reliable Exports

Preparing Rhino models for real-time engines (Unity, Unreal, Twinmotion, Omniverse, Enscape) is about disciplined cleanup, efficient meshing, and predictable exports.

Before you mesh

• Set units and scale early: Units command. Match your target engine (centimeters for Unreal, meters for many others). Keep Absolute tolerance reasonable (e.g., 0.01 in model units).
• Stay near the world origin to avoid floating-point artifacts in engines. Move your assembly so the main object sits around 0,0,0.
• Name everything: layers, objects, and materials. These become nodes and slots in-engine and make scene management far easier.
• Block wisely for repeated parts; engines can instance them. Define sensible block base points to serve as pivots.
• Run quality checks: SelBadObjects, ShowEdges (non-manifold, naked), and MeshRepair for any meshes from scans or imports.

Create efficient, game-ready meshes

• Control tessellation explicitly: Mesh command with Detailed controls. Aim for:
  • Max angle: 6–12 degrees for smooth parts; higher for planar/mechanical.
  • Max edge length: clamp long edges on large faces to avoid stretched triangles.
  • Simple planes = Yes to keep planar faces light.
• Weld smoothing: Weld at 30–60 degrees so shading is continuous where needed and hard at sharp breaks.
• Reduce where it doesn’t hurt: ReduceMesh with Preserve boundaries and Prevent distortion. Create multiple LODs (e.g., _LOD0, _LOD1, _LOD2).
• Normals matter: UnifyMeshNormals and check in Rendered view. Flip if any faces shade dark.
• For organic forms, QuadRemesh can generate clean, animator-friendly topology before converting to mesh.

UVs and textures that just work

• Unwrap explicitly: Unwrap and UVEditor. Pack islands with PackTextures and set uniform texel density across parts.
• Use simple mapping for primitives (BoxMapping, CylindricalMapping) to save time.
• Name materials clearly and limit count to reduce draw calls. Prefer PBR with Base Color, Roughness, Metallic, Normal.
• Centralize textures and keep paths relative. On save/export, enable “Save textures” to package them.

Export settings that survive the round-trip

• Format:
  • FBX: most common for Unity/Unreal; enable Smoothing groups, Triangulate, and Embed media when possible.
  • OBJ: robust for static assets; export Triangles and include texture coordinates.
  • glTF/GLB: great for web and many viewers; keeps PBR consistent and portable.
• Up-axis:
  • Unity: Y-up (map Rhino Z to Y in export).
  • Unreal: Z-up (Rhino default; keep as-is).
• Instances: export blocks as instances to preserve engine instancing.
• Combine by material when appropriate to reduce draw calls, but keep logical splits for interactions and LODs.

Final checks

• Open in the target engine and verify scale, pivots, and shading. Adjust weld angle or normals if you see unexpected creases.
• Profile triangle counts and materials. Budget early to avoid late-stage rework.

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