Kelsi 9490ce98c5 fix(water): break the refraction feedback loop; halve the capture cost ...

The refraction copy was taken from the finished frame, which already had
the water composited into it, so the water sampled its own output every
frame. A moving object left one sharp copy per frame — a train of ghosts
rather than a wake — and the display brightness the water divided back
out compounded through the loop, so the surface pumped as the camera
moved.

Draw the water in a continuation of the scene pass instead. The frame now
runs scene, copy, water, UI: the copy is taken at the one point where the
scene is finished and the water is not yet over it. The copy is also
same-frame rather than a frame behind, and being pre-post-processing it
carries no baked-in brightness, so the shader drops both the divide that
compensated for it and the temporal lag.

Two supporting changes. The capture scales with a blit when the scene is
not rendered at the history's resolution, which FSR does — previously the
smaller scene was copied into the corner of a larger history and sampled
as though it filled it. And the history is now half resolution: a quarter
of the pixels copied per frame and a quarter of the sampling footprint,
which is not visible through a surface that displaces the sample by a few
rippling pixels regardless.

Water stays in the scene pass under MSAA, where a continuation pass would
have to resolve a second time; that path keeps the old end-of-frame copy.

2026-07-31 07:22:15 -07:00

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