Phase 3 -- YCoCg neighbourhood variance clamp: the reprojected history is forced
into the colour box (mean +/- gamma*sigma) of the current frame's 3x3
neighbourhood in YCoCg, crushing the doubling/smearing the reconstructed motion
field leaves while preserving the marble-steady smoothing at rest.
RYUJINX_TAA_CLAMP tunes the box half-width (default 1.0).
Phase 4 -- reduced-resolution optical flow: the colour is bilinear-downsampled to
1/N (default half) and Lucas-Kanade + the 3x3 median run there (~N^2 less work,
the dominant cost), then the field is bilinear-upscaled and scaled by N in the
blend. The per-frame full-res previous-color copy is gone. RYUJINX_TAA_MV_DOWNSCALE
sets the divisor (1/2/4, default 2). New TaaDownsample shader. Validated: 60 FPS
at x3 with the Phase 3 quality preserved.
Velocity-drop hysteresis -- removes the single-frame flash on a hard stop: a
per-pixel smoothed velocity (carried in the history alpha) rises instantly with
motion but decays over several frames, and both the clamp width and blend weight
are continuous functions of it, so the static 'marble' reasserts gradually
instead of snapping. Decay 0.85 for large distant surfaces (waterfalls).
All gated on RYUJINX_TAA=1; default render path unchanged when off.
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