Add Optimized Gyroid infill (auto-tuned wavelength + amplitude)

[peyton-marcotte]

Summary

Adds a new infill geometry, Optimized Gyroid, derived from FillGyroid. Two parameters that control the wave shape are auto-computed per region from the density, line spacing, and layer height. The user does not see or set them. Density is still picked by the user.

The new pattern appears as "Optimized Gyroid" in the Fill Pattern dropdown alongside the standard Gyroid.

Physics

Standard gyroid surface: sin(x)cos(y) + sin(y)cos(z) + sin(z)cos(x) = 0. The optimized variant scales x by ω (frequency) and the output by A (amplitude):

Parameter	Formula	Bounds	Rationale
ω (omega)	sqrt(density_adj) / sqrt(1 + layer_h / spacing)	[0.5, 2.0]	Euler-Bernoulli buckling: P_cr ∝ 1/L². Shorter wavelength under denser infill raises the critical buckling load of each strand.
A (amplitude)	0.55 / ω²	[0.20, 0.65]	Curved-beam bending: peak fiber stress σ ∝ A·ω². Dropping A as ω rises keeps strand peak stress bounded while preserving stiffness.

Net effect: at low density it looks like a normal gyroid; at higher density walls develop a tighter, lower-amplitude waviness intended to resist load-direction buckling. Density continues to control mass and interlayer adhesion.

Files changed

New FillOptimizedGyroid.{hpp,cpp} plus the standard set of integration points (factory, switch cases, enum, label, CMakeLists). The integration mirrors the existing FillGyroid registration in this codebase exactly.

Testing state

Honest disclosure: the patch is submitted as a draft because it has not been compile-verified locally. The integration points are a 1:1 mirror of the existing FillGyroid registration in this repo, and the algorithm is a parameterized extension of FillGyroid.cpp's wave generator. The project's CI is the authoritative check. Happy to iterate on any compile or review feedback.

No changes to existing infill behavior. The new pattern is additive.

Why "Optimized Gyroid" as a separate option, not changes to Gyroid?

Density-tuned wavelength and amplitude change the visual and mechanical character of the infill. Keeping it as a separate selectable pattern means users opting in get the new behavior; existing prints and profiles using gyroid are untouched.

Origin

Developed as part of the CRAMP project at Brown University: Compression Research for Additive Manufacturing Performance. CRAMP identifies and validates high-performance additive-manufacturing infill architectures for compression in spaceflight applications, where every gram and every Newton of load matters.

Candidate architectures were generated by a custom AI over the space of triply-periodic minimal-surface (TPMS) infills, then printed and compression-tested on the Instron press at Brown University's Prince Laboratory against standard rectilinear and concentric baselines. Winning architectures beat commodity baselines by up to 60% in compressive strength-to-mass. The Optimized Gyroid pattern submitted here is a parameterized variant of one such candidate, surfaced from that search.

Sponsors and partners:

• NASA: funded research, two NASA Space Grant awards via Rhode Island Space Grant (RISG)
• Rhode Island Space Grant (RISG): administering body of the Space Grant funding
• Brown University: host institution; compression testing performed at the Prince Laboratory on the Instron press
• ELEGOO 3D: industry collaborator under signed Memorandum of Understanding
• Polymaker: filament sponsor

Released open source for community use.