The source is uploaded once per view (kept with the GPU stages) and resampled on
the device: orientation as an integer pixel map, the Mitchell area prefilter
with the CPU's exact taps, then one bilinear resample through the
crop/straighten/flip affine or through the full warp (inverse perspective,
manual distortion, embedded DNG WarpRectilinear per plane, lateral CA, manual
and embedded vignetting gain, blank outside the source). `Frame::sample_plan`
(new) decides prefilter size and mode for both renderers; sources larger than
the device's buffer limit are still resampled on the CPU.
Equivalence: all 8 orientations with and without crop/straighten/flip, embedded
lens + perspective: max 1 LSB.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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