Supersampling resolve filters + optional RCAS sharpening

[PEQHUB]

Supersampling resolve filters + optional RCAS sharpening

Base: Zolo101/RenderScale @ stonecutter · Head: PEQHUB:feat/supersampling-filters · Commit: 6b888b9

What it does

When the render scale is above 100%, the downscale from the render target to the window currently uses a single bilinear fetch. This adds two resolve filters, selectable in the config:

• Rotated Grid — 4 taps on the classic rotated grid. Best around 2x.
• Sparse Grid — 8 taps as two half-scale rotated-grid quads. Used at 3x and above; falls back to Rotated Grid below that.

Both filter the already-rendered image; they do not add geometry coverage samples. Below 100% scale, nothing changes.

Optional RCAS sharpening (Off / RCAS / RCAS with noise protection) offsets the resolve softening. It runs at AMD's FSR1 reference tuning over the shared output-sized intermediate, blending towards the unsharpened pixel so strength is a plain 0-100% control. Default 35%. 0% or Off skips the pass entirely. The FSR path is never sharpened.

Implementation notes

• New branch in blitAndBlendToTexture for render-target-larger-than-output; mutually exclusive with FSR upscaling by construction.
• No supported version exposes a float uniform setter on a render pass, so strength is a shader define over a lazily built preset cache (21 presets x 2 noise modes). Stored strength is normalized to the same 5% presets on load, save, and slider input.
• One rcas.fsh serves FSR and sharpening; the blend/noise defines are optional, so FSR's output is unchanged. Version-specific pipeline building is one RenderPipeline.Builder factory; the fullscreen pass and intermediate-target handling are shared helpers.
• Controls are on the main page in both the Cloth and Sodium UIs, guarded to 1.21.11+ like the fsr option. Older versions are untouched (slider ranges revert to 200%).
• Dev-only gametest classes are excluded from the shipped jars.

Testing

• Builds on 1.21.11-fabric, 26.2-fabric, 26.2-neoforge, 26.3-fabric.
• Filter math was verified against a box reference and a CPU RCAS port anchored to GPU-measured values during development (harness kept out of the repo).
• In-game on 26.2-fabric, 149-mod pack, RTX 5090: clean load/exit, RGSS at 200% and SGSS at 400% visually confirmed.

Known limitations

• The 300% filter switch is a hard threshold; quality jump around 300% needs playtesting.
• Iris verified with shader packs disabled only.
• SGSS is not perfectly isotropic on reflected diagonals (noted in the shader).
• Driver-style rasterizer SGSSAA isn't possible through the current API; these are resolve-side filters.