Add -substeps: trade solver accuracy for CPU headroom on slower hardware - #40
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substeps (native: 3, wasm: 1) was a const tuned for each build target's own measured per-step cost, with no way to adjust it for hardware in between -- a Raspberry Pi 5, for instance, running the exhibit's actual 24-mic acoustic localization display alongside kutta, benefits from trading a substep or two for headroom. Converts both build-tagged consts to vars and adds -substeps to override either one at runtime, no rebuild needed. Validated on-device: dropping from 3 to 2 on a Pi 5 cut solver time from ~15ms to ~10-11ms per tick (measured with -debug), the difference between visibly catching up to the tick rate and visibly falling behind it, at the cost of the accuracy that one fewer LBM step per displayed frame represents.
crgimenes
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Aug 3, 2026
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Validated on the hardware that motivated it, and the flag composes with -tps/-warp correctly. Merging, thanks.
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Closes #39.
Converts both build-tagged `substeps` consts to vars and adds `-substeps` to override either one at runtime, no rebuild needed.
Validated on-device: dropping from 3 to 2 on a Pi 5 cut solver time from ~15ms to ~10-11ms per tick (measured with `-debug`) — the difference between visibly catching up to the tick rate and visibly falling behind it, at the cost of the accuracy that one fewer LBM step per displayed frame represents.
Tested: `go test ./...` passes, plus a native and WASM build (this touches both build-tagged files).