feat(gfx): v2.2.8 "Aperture II" — gamma-correct + sharper scanlines

CHANGELOG.md

@@ -14,6 +14,46 @@ cycle-accurate core later replaced.
 
 ## [Unreleased]
 
+## [2.2.8] - 2026-08-04 - "Aperture II" (gamma-aware scanlines + sharper CRT)
+
+A **presentation-fidelity** release addressing the NESdev-forum feedback on
+gamma-aware resampling and bilinear-soft scanlines. **Presentation-only — nothing
+here touches the emulation core**, so the pre-shader framebuffer, save-states, and
+every golden vector are byte-identical (AccuracyCoin 141/141, nestest 0-diff), and
+the **shipped native default is byte-identical** to v2.2.7 (the native sRGB
+surface passes `aux = 0`, which selects the exact pre-v2.2.8 scanline profile;
+the new linear-light + sharper-scanline path activates only for a non-zero
+`aux`, set on the WebGL2 non-sRGB path and when the scanline knob is raised).
+The base BLEP audio and the advanced CRT stacks
+(royale/guest/megatron, already gamma-correct) are untouched.
+
+> **Visual verification pending.** These are shader/appearance changes; naga
+> validates that the WGSL compiles and the native/wasm builds are clean, but the
+> on-screen result must be confirmed on a real display + a browser (WebGL2).
+
+### Changed
+
+- **Gamma-correct scanlines + aperture mask (base CRT pass, `CRT_WGSL`).** The
+  scanline/mask *darkening* now happens in **linear light**. On the native path
+  (sRGB texture + surface) the sampler/surface already convert, so the shader
+  leaves it linear (`aux.y = 0`, output byte-identical). On a plain UNORM path
+  (**WebGL2**, which does neither) the shader now sRGB-decodes on read and
+  re-encodes before output (`aux.y = 1`) — fixing a real browser-only gamma bug so
+  a scanline valley is 50% of the *linear* luminance, not the encoded value. The
+  round-trip uses the **exact IEC 61966-2-1 piecewise sRGB transfer** (the
+  `0.04045` / `0.0031308` breakpoints + a 2.4 exponent), not a `pow(2.2)`
+  approximation, so the WebGL2 result matches the hardware sRGB surface the native
+  path uses bit-for-bit.
+- **Sharper scanlines (`aux.x`, default 0.5).** The scanline profile blends from
+  the original soft parabola (0) to a narrow Gaussian beam (1) for crisp vertical
+  boundaries instead of the linear-sampler blur — the sharper scanlines the
+  feedback asked for. Only visible when scanlines are enabled; `aux.x = 0`
+  reproduces the pre-v2.2.8 profile exactly. Wired on the desktop
+  (`rustynes-frontend`), Android (`rustynes-android`), and iOS Metal
+  (`rustynes-ios`) hosts via the shared 16-float CRT uniform
+  (`rect + crop + params + aux`) — all three set `aux` identically for the
+  scanline/CRT filters, so the corrected profile is consistent across platforms.
+
 ## [2.2.7] - 2026-08-04 - "Timbre II" (expansion-audio fidelity: VRC6 + Sunsoft 5B)
 
 An **expansion-audio accuracy** release addressing NESdev-forum feedback. Driven by a

Cargo.toml

@@ -32,7 +32,7 @@ members = [
 default-members = ["crates/rustynes-libretro"]
 
 [workspace.package]
-version = "2.2.7"
+version = "2.2.8"
 edition = "2024"
 rust-version = "1.96"
 license = "MIT OR Apache-2.0"

README.md

@@ -9,7 +9,7 @@
 </p>
 
 <p align="center">
-  <a href="https://github.com/doublegate/RustyNES/actions"><img src="https://github.com/doublegate/RustyNES/workflows/CI/badge.svg" alt="Build Status"></a> <a href="#license"><img src="https://img.shields.io/badge/license-MIT%20OR%20Apache--2.0-blue.svg" alt="License: MIT OR Apache-2.0"></a> <a href="https://github.com/doublegate/RustyNES/releases"><img src="https://img.shields.io/badge/version-v2.2.7-blue.svg" alt="Version"></a> <a href="rust-toolchain.toml"><img src="https://img.shields.io/badge/rust-1.96-orange.svg" alt="Rust: 1.96"></a><br>
+  <a href="https://github.com/doublegate/RustyNES/actions"><img src="https://github.com/doublegate/RustyNES/workflows/CI/badge.svg" alt="Build Status"></a> <a href="#license"><img src="https://img.shields.io/badge/license-MIT%20OR%20Apache--2.0-blue.svg" alt="License: MIT OR Apache-2.0"></a> <a href="https://github.com/doublegate/RustyNES/releases"><img src="https://img.shields.io/badge/version-v2.2.8-blue.svg" alt="Version"></a> <a href="rust-toolchain.toml"><img src="https://img.shields.io/badge/rust-1.96-orange.svg" alt="Rust: 1.96"></a><br>
   <a href="#compatibility-and-accuracy"><img src="https://img.shields.io/badge/AccuracyCoin-100%25%20(141%2F141)-brightgreen.svg" alt="AccuracyCoin"></a> <a href="#compatibility-and-accuracy"><img src="https://img.shields.io/badge/nestest-0--diff-brightgreen.svg" alt="nestest"></a> <a href="https://doublegate.github.io/RustyNES/"><img src="https://img.shields.io/badge/play-in%20browser-success.svg" alt="Try in browser"></a><br>
   <a href="#platform-support"><img src="https://img.shields.io/badge/platform-Windows%20%7C%20Linux%20%7C%20macOS%20%7C%20Web%20%7C%20Android%20%7C%20iOS-lightgrey.svg" alt="Platform"></a>
 </p>
@@ -795,7 +795,12 @@ and the Material-for-MkDocs documentation handbook at
 
 ## Current Release
 
-RustyNES's current release is **v2.2.7 "Timbre II"**, an **expansion-audio fidelity**
+RustyNES's current release is **v2.2.8 "Aperture II"**, a **presentation-fidelity**
+release: gamma-correct scanlines (linear-light darkening + a WebGL2 gamma fix) and a
+sharper Gaussian scanline profile for crisp vertical boundaries. Presentation-only —
+the pre-shader framebuffer is byte-identical (**AccuracyCoin 141/141**) and the shipped
+native default is unchanged; the shader/appearance changes await on-display + browser
+visual verification. It builds on **v2.2.7 "Timbre II"**, an **expansion-audio fidelity**
 release: VRC6 recalibrated to the field/NESdev consensus (a VRC6 pulse ≈ a 2A03 pulse,
 ~1.0× — Mesen2 was the loud outlier), and the Sunsoft 5B envelope moved to the exact 5-bit
 1.5 dB/step DAC (matching nestopia/rustico). Expansion-only, so the base 2A03 output is
@@ -1042,7 +1047,7 @@ If you use RustyNES in academic research, please cite:
   author  = {RustyNES Contributors},
   title   = {RustyNES: A Cycle-Accurate NES Emulator in Rust},
   year    = {2026},
-  version = {2.2.7},
+  version = {2.2.8},
   url     = {https://github.com/doublegate/RustyNES},
   note    = {Cycle-accurate NES emulator on a master-clock-precise scheduler;
              AccuracyCoin 100\% (141/141), nestest 0-diff; 172 mapper families,

crates/rustynes-android/src/gfx.rs

@@ -39,7 +39,8 @@ struct Uniforms {
     crop: [f32; 4],
     // CRT: (scanline, mask, _, _). NTSC: (saturation, sharpness, tint, phase).
     params: [f32; 4],
-    // NTSC only: x = PAL mode. Padding for the CRT shader (which reads 12 floats).
+    // CRT (v2.2.8): x = scanline sharpness, y = gamma-linearize flag.
+    // LMP-NTSC: x = PAL mode. Bisqwit: picture knobs.
     aux: [f32; 4],
 }
 
@@ -441,10 +442,23 @@ impl AndroidGfx {
             (1.0, screen_aspect / IMG_ASPECT) // letterbox
         };
         // For CRT/scanline/LMP-NTSC the `params` come straight from the per-filter
-        // sliders (aux unused). For Bisqwit (filter 4) `params.x` is the per-frame
-        // videoPhase and the picture knobs (contrast/sat/bright/hue) ride in `aux`.
+        // sliders. For Bisqwit (filter 4) `params.x` is the per-frame videoPhase and
+        // the picture knobs (contrast/sat/bright/hue) ride in `aux`.
+        //
+        // v2.2.8 "Aperture II": the CRT/scanline pass (filters 1, 2) now reads
+        // `aux.x` = scanline sharpness and `aux.y` = a gamma-linearize flag (1 on a
+        // plain UNORM surface so the shader keeps the darkening in linear light; 0 on
+        // an sRGB surface where the sampler/surface already convert). Filters 0 (none)
+        // and 3 (LMP-NTSC) keep `aux = 0` (LMP-NTSC's PAL flag rides its own path).
+        let crt_linearize = if self.config.format.is_srgb() {
+            0.0
+        } else {
+            1.0
+        };
         let (params, aux) = if self.filter == 4 {
             ([f32::from(self.ntsc_phase), 0.0, 0.0, 0.0], self.params)
+        } else if self.filter == 1 || self.filter == 2 {
+            (self.params, [0.5, crt_linearize, 0.0, 0.0])
         } else {
             (self.params, [0.0, 0.0, 0.0, 0.0])
         };

crates/rustynes-frontend/src/crt.rs

@@ -122,6 +122,16 @@ pub struct CrtFilter {
     scanline: f32,
     /// Aperture-mask intensity (fixed-subtle for the MVP).
     mask: f32,
+    /// v2.2.8 "Aperture II": scanline beam sharpness (aux.x, 0 = the original soft
+    /// parabola .. 1 = a crisp Gaussian beam for sharp vertical boundaries). Only
+    /// visible when `scanline > 0`.
+    sharpness: f32,
+    /// v2.2.8: gamma round-trip flag (aux.y). `1.0` when the surface is a plain
+    /// UNORM (e.g. WebGL2) so the shader must sRGB-decode/encode around the
+    /// scanline+mask darkening to keep it in linear light; `0.0` on an sRGB
+    /// surface where the sampler + surface already handle the gamma conversion
+    /// (so the shipped native output stays byte-identical).
+    linearize: f32,
 }
 
 impl CrtFilter {
@@ -216,13 +226,19 @@ impl CrtFilter {
         });
         let scanline = scanline.clamp(0.0, 1.0);
         let mask = 0.10; // subtle fixed grille for the MVP.
+        // v2.2.8: crisper scanlines by default (only visible when scanline > 0), and
+        // the gamma round-trip flag derived from the surface's color space (sRGB ->
+        // 0 = leave linear; plain UNORM/WebGL2 -> 1 = decode/encode in the shader).
+        let sharpness = 0.5;
+        let linearize = if surface_format.is_srgb() { 0.0 } else { 1.0 };
         let uniforms = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
             label: Some("crt-uniforms"),
-            // rect (identity letterbox) + crop (none) + params (scanline, mask).
+            // rect + crop + params (scanline, mask, rows, _) + aux (sharpness, linearize, _, _).
             contents: bytemuck::cast_slice(&[
                 1.0f32, 1.0, 0.0, 0.0, // rect
                 1.0, 0.0, 1.0, 0.0, // crop (v-scale, v-off, u-scale, u-off)
                 scanline, mask, 0.0, 0.0, // params
+                sharpness, linearize, 0.0, 0.0, // aux
             ]),
             usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
         });
@@ -251,6 +267,8 @@ impl CrtFilter {
             bind_group,
             scanline,
             mask,
+            sharpness,
+            linearize,
         }
     }
 
@@ -274,7 +292,7 @@ impl CrtFilter {
         par_correction: bool,
         overscan: crate::config::Overscan,
     ) {
-        // rect (4) + crop (4) from the shared helper, then the CRT params (4).
+        // rect (4) + crop (4) from the shared helper, then params (4) + aux (4).
         let lb = crate::gfx::letterbox_uniform(width, height, par_correction, overscan);
         let uniform = [
             lb[0],
@@ -289,6 +307,10 @@ impl CrtFilter {
             self.mask,
             0.0,
             0.0,
+            self.sharpness,
+            self.linearize,
+            0.0,
+            0.0,
         ];
         queue.write_buffer(&self.uniforms, 0, bytemuck::cast_slice(&uniform));