Add spiralized toolpaths for CAM operations

[jeffc]

This change adds continous "spiral" toolpath options to the contour, pocket, area, rough, and level operations. The spiral is formed by continous interpolation between successive offset contours such that the tool can move continously, rather than tracing an offset, pausing, then moving outwards to the next one. The spiral is computed such that the stepover at any point around the contour is still respected. The existing behavior (trace one offset contour before moving to the next) has been renamed to "concentric" to differentiate it from the spiral mode.

Note: Javascript is not my strongest language, and much of this change was authored with significant assistance from AI tools. If you'd like to keep your codebase AI-free I totally understand, but I do find this feature personally useful (especially for finishing passes) so I figured I'd share :)

Thanks for such a great tool!

[stewartoallen]

great idea. this contains a few sizable core changes (polygon, op_area) that make me a bit nervous and could cause regressions all over the place. i'll spend more time reviewing and testing. not opposed to AI generated code. it does require careful review, esp when it was crafted without expert oversight.

[jeffc]

Great! I tested every case I could think of (and I agree about being uneasy about changing the core geometry libs, but that felt better than duplicating code in a bunch of places), but please let me know if there's any case I missed. Thanks again for making this project what it is!

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On Wed, Jun 3, 2026, 18:23 Stewart Allen ***@***.***> wrote: *stewartoallen* left a comment (GridSpace/grid-apps#487) <#487 (comment)> great idea. this contains a few sizable core changes (polygon, op_area) that make me a bit nervous and could cause regressions all over the place. i'll spend more time reviewing and testing. not opposed to AI generated code. it does require careful review, esp when it was crafted without expert oversight. — Reply to this email directly, view it on GitHub <#487?email_source=notifications&email_token=AAAKTRVID44QM4ANJDDJUHD46CQMFA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRRG4ZDANZQHA22M4TFMFZW63VGMF2XI2DPOKSWK5TFNZ2KYZTPN52GK4S7MNWGSY3L#issuecomment-4617207085>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAKTRQ4BPKO7LJMT65P7LD46CQMFAVCNFSM6AAAAACZZLN6SKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DMMJXGIYDOMBYGU> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AAAKTRS43RWPQESGZI43M5L46CQMFA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRRG4ZDANZQHA22M4TFMFZW63VGMF2XI2DPOKSWK5TFNZ2KUZTPN52GK4S7NFXXG> and Android <https://github.com/notifications/mobile/android/AAAKTRSTBWUXNCV7RUHM6R346CQMFA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRRG4ZDANZQHA22M4TFMFZW63VGMF2XI2DPOKSWK5TFNZ2K4ZTPN52GK4S7MFXGI4TPNFSA>. Download it today! You are receiving this because you authored the thread.Message ID: ***@***.***>

[jeffc]

I've been using this locally, and can confirm that spiral contouring makes for a very clean surface finish. I was carving a mountain out of aluminum with a 1/8" ballnose mill, and the tool marks are basically invisible unless you look really closely in the right light.

I did just find and fix a bug where there were some retractions missing for multi-layer spiralized paths (roughing, pocket, etc), so if you're testing be sure to pull in that latest commit.