Homography::apply, Affine::apply, Warp::to_corrected,
Warp::corrected_to_source and embedded_warp are now generic over
lightcraft_geom::Real (private *_real variants in pipeline, public
apply_real in geom); the f64 API is a thin wrapper, so callers are
unchanged. Real is implemented for f64 (plain IEEE operators) and for
Interval, which rounds every bound one ulp outward and turns division by
a range containing zero, the homography's 1e-300 denominator clamp and
non-finite bounds into "undecided" (NaN). Because the interval runs the
same operations as the f64 path, it bounds the rounded f64 results, not
only the exact ones.
The f64 path keeps the same operations in the same order (only commuted
operands, which IEEE + and x leave bit-identical; no fma). Proof:
warp_f64_results_are_bit_identical_to_the_pre_generic_formulas hashes the
bits of 2000 random warps x 40 points through every formula (plus the
clamp branch, including +-1e-300 exactly) and matches the digest computed
by the same test on thumb-split (419261c) before the change; reassociating
one expression, or `<=` for `<` in the clamp, changes it.
The framing chain (output px -> transformed -> lens-corrected -> green
source, then inside the edges) is written once: Warp::framing, generic.
Warp::frame (f64, returns the corrected and green source points) serves
both the CPU resample (sample_warped) and Warp::covers; block_coverage
evaluates the same chain with intervals over a whole block of output
pixels and compares the bounds against the same edges() inside uses, with
no margin: the bounds enclose every pixel's f64 result, so the decision
equals the per-pixel one; else None.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2b2ebfc7ca