Modern Lossless Dynamic Quantization Scanline Shader (#3731)

Update scanline-modern-ex.fx

data/resources/shaders/reshade/Shaders/scanline-modern-ex.fx

@@ -0,0 +1,139 @@
+#include "ReShade.fxh"
+
+/*
+
+This shader is not designed to simply simulate the scanline + cross grid effect of old CRT monitors. 
+Instead, it aims to combine the advantages of sharp clarity on modern displays with retro games, 
+enabling better pixel-level scaling.
+The generation intensity of scanlines is dynamically quantized and adjusted based on the human eye's 
+perceptual curve for chromatic brightness, rather than using rigid stripe overlay.
+
+Core Features:
+- Supports independent adjustment of vertical scanline and horizontal crossline intensity/density, 
+  adapting to different resolutions (1080P/4K / high-magnification scaling);
+- Default parameters are suitable for most pixel games scaled up on large modern 4K resolution screens, 
+  with lossless brightness/color;
+- Optimized scanline performance based on human eye brightness sensitivity curve: 
+  scanlines are prominent in medium brightness areas and weakened in extreme brightness areas;
+- Adjustable color channel quantization attenuation, suitable for games like GBA that have 
+  hardware-encoded gamma bias (over-bright/grayed out) due to lack of backlighting. 
+  It can perfectly restore vivid colors. 
+
+    Perceptual Sensitivity Curve:
+    Sensitivity
+      ↑
+      |        Peak Sensitivity (0.4-0.6 Luma)
+      |           / \
+      |          /   \
+      |         /     \____ High-luma roll-off
+      |        /
+      +--------------------→ Luminance (0.0 - 1.0)
+
+	 * (C) 2025-2026 by crashGG.
+*/
+
+// --- UI Parameters ---
+
+uniform float sinCompY <
+    ui_type = "drag";
+    ui_min = 0.0;
+    ui_max = 1.0;
+    ui_label = "Vertical Scanline Intensity";
+    ui_tooltip = "Intensity of horizontal lines (Y-axis oscillation).";
+> = 0.1;
+
+uniform float sinCompX <
+    ui_type = "drag";
+    ui_min = 0.0;
+    ui_max = 0.10;
+    ui_step = 0.01;
+    ui_label = "Horizontal Grid Intensity";
+    ui_tooltip = "Intensity of vertical lines (X-axis oscillation), creating a shadow mask effect.";
+> = 0.01;
+
+uniform float densY <
+    ui_type = "drag";
+    ui_min = 1.0;
+    ui_max = 6.0;
+    ui_step = 1.0;
+    ui_label = "Scanline Density";
+    ui_tooltip = "Frequency of scanlines. Recommended: 3.0 for 1080P, 2.0 for 4K.";
+> = 3.0;
+
+uniform float densX <
+    ui_type = "drag";
+    ui_min = 0.5;
+    ui_max = 1.0;
+    ui_step = 0.5;
+    ui_label = "Grid Density";
+    ui_tooltip = "Density multiplier for the horizontal grid.";
+> = 1.0;
+
+uniform float colAtten <
+    ui_type = "drag";
+    ui_min = 0.0;
+    ui_max = 2.0;
+    ui_label = "Chroma Attenuation";
+    ui_tooltip = "Adjusts color quantization depth. Useful for correcting washed-out retro titles (e.g., GBA).";
+> = 0.0;
+
+#define PI 3.141592654
+
+// --- Pixel Shader ---
+
+float4 PS_SineScanline(float4 vpos : SV_POSITION, float2 texcoord : TEXCOORD0) : SV_Target
+{
+    // 1. Texture Sampling
+    // Apply a micro-offset (1.0001) to UVs to prevent edge bleeding on certain hardware
+    float2 uv = texcoord * 1.0001;
+    float3 res = tex2D(ReShade::BackBuffer, uv).rgb;
+
+    // 2. Frequency Calculation (Omega)
+    // Map coordinate space to angular frequency. 
+    // Uses 1.999 factor on Y-axis to avoid integer-multiple aliasing (Moire patterns).
+    float2 omega = float2(
+        PI * BUFFER_WIDTH * densX, 
+        1.999 * PI * BUFFER_HEIGHT / densY
+    );
+
+    // 3. Sine Wave Generation
+    // Project UVs into periodic sine space for smooth transitions
+    float2 tex_omega_product = uv * omega;
+    float2 sine_wave = sin(tex_omega_product);
+    
+    // 4. Amplitude Modulation
+    float2 scaled_sine_wave = float2(sinCompX, sinCompY) * sine_wave;
+    
+    // 5. Signal Summation
+    // Combine X and Y oscillations into a single scalar fluctuation value
+    float total_sine_fluctuation = scaled_sine_wave.x + scaled_sine_wave.y;
+
+    // 6. Luma-Aware Perceptual Weighting (dist)
+    // Calculates squared distance from neutral gray (0.5).
+    // This ensures scanlines fade out in pure blacks and pure whites.
+    float3 dist_linear = abs(res - 0.5) * 2.0;
+    float3 dist = dist_linear * dist_linear;
+
+    // 7. Final Luma Modulation
+    // Component A: Chroma attenuation based on grid intensity
+    // Component B: Dynamic sine oscillation
+    // Both components are gated by the 'weight' (1.0 - dist) for perceptual balance.
+    float3 weight = 1.0 - dist;
+    float3 final_brightness = 1.0 - ((sinCompX + sinCompY) * weight * colAtten) + total_sine_fluctuation * weight;
+
+    // 8. Output Composition
+    float3 scanline = res * final_brightness;
+
+    return float4(scanline, 1.0);
+}
+
+// --- Technique Definition ---
+
+technique Modern_Sine_Scanlines 
+{
+    pass P0 
+    {
+        VertexShader = PostProcessVS;
+        PixelShader = PS_SineScanline;
+    }
+}