From acaade10628ed3478ef9837868693050bdd31b24 Mon Sep 17 00:00:00 2001
From: minjaesong <alswo9628@gmail.com>
Date: Wed, 26 Nov 2025 00:39:00 +0900
Subject: [PATCH] better CRT/Composite shader

---
 assets/disk0/home/jpdectest.js                |  22 +-
 assets/disk0/home/jpdectesthigh.js            |  22 +-
 .../src/net/torvald/tsvm/shader_crt_post.frag | 322 ++++++++++++++++++
 tsvm_executable/src/net/torvald/tsvm/VMGUI.kt | 199 +----------
 4 files changed, 337 insertions(+), 228 deletions(-)
 create mode 100644 tsvm_core/src/net/torvald/tsvm/shader_crt_post.frag

diff --git a/assets/disk0/home/jpdectest.js b/assets/disk0/home/jpdectest.js
index 884691d..7c1940b 100644
--- a/assets/disk0/home/jpdectest.js
+++ b/assets/disk0/home/jpdectest.js
@@ -2,26 +2,18 @@ if (!exec_args[1]) {
     printerrln("Usage: jpdectest image.jpg")
 }
 
-filesystem.open("A", exec_args[1], "R")
+const fullFilePath = _G.shell.resolvePathInput(exec_args[1])
+const file = files.open(fullFilePath.full)
+const fileLen = file.size
+const infile = sys.malloc(file.size); file.pread(infile, fileLen, 0)
 
-let status = com.getStatusCode(0)
-let infile = undefined
-if (0 != status) return status
-
-
-let fileLen = filesystem.getFileLen("A")
-println(`DMA reading ${fileLen} bytes from disk...`)
-infile = sys.malloc(fileLen)
-dma.comToRam(0, 0, infile, fileLen)
-
-
-println("decoding")
+//println("decoding")
 
 // decode
 const [imgw, imgh, channels, imageData] = graphics.decodeImageResample(infile, fileLen, -1, -1)
 
-println(`dim: ${imgw}x${imgh}`)
-println(`converting to displayable format...`)
+//println(`dim: ${imgw}x${imgh}`)
+//println(`converting to displayable format...`)
 
 // convert colour
 graphics.setGraphicsMode(0)
diff --git a/assets/disk0/home/jpdectesthigh.js b/assets/disk0/home/jpdectesthigh.js
index 9b45b17..9c49d7f 100644
--- a/assets/disk0/home/jpdectesthigh.js
+++ b/assets/disk0/home/jpdectesthigh.js
@@ -2,26 +2,18 @@ if (!exec_args[1]) {
     printerrln("Usage: jpdectesthigh image.jpg")
 }
 
-filesystem.open("A", exec_args[1], "R")
+const fullFilePath = _G.shell.resolvePathInput(exec_args[1])
+const file = files.open(fullFilePath.full)
+const fileLen = file.size
+const infile = sys.malloc(file.size); file.pread(infile, fileLen, 0)
 
-let status = com.getStatusCode(0)
-let infile = undefined
-if (0 != status) return status
-
-
-let fileLen = filesystem.getFileLen("A")
-println(`DMA reading ${fileLen} bytes from disk...`)
-infile = sys.malloc(fileLen)
-dma.comToRam(0, 0, infile, fileLen)
-
-
-println("decoding")
+//println("decoding")
 
 // decode
 const [imgw, imgh, channels, imageData] = graphics.decodeImageResample(infile, fileLen, -1, -1)
 
-println(`dim: ${imgw}x${imgh}`)
-println(`converting to displayable format...`)
+//println(`dim: ${imgw}x${imgh}`)
+//println(`converting to displayable format...`)
 
 // convert colour
 graphics.setGraphicsMode(4)
diff --git a/tsvm_core/src/net/torvald/tsvm/shader_crt_post.frag b/tsvm_core/src/net/torvald/tsvm/shader_crt_post.frag
new file mode 100644
index 0000000..5cba0bb
--- /dev/null
+++ b/tsvm_core/src/net/torvald/tsvm/shader_crt_post.frag
@@ -0,0 +1,322 @@
+
+
+// ============================================================================
+// CRT + NTSC Composite/S-Video Signal Simulation Shader (Enhanced Version)
+// ============================================================================
+// Features:
+// - Runtime-switchable composite/S-Video mode (no recompilation)
+// - Adjustable signal and CRT parameters via uniforms
+// - Accurate NTSC color artifact simulation
+// - Animated dot crawl effect
+// - Trinitron phosphor mask
+// - Optional bloom/glow effect
+// ============================================================================
+
+// === UNIFORMS ===
+uniform float time = 0.0;              // Frame count
+uniform vec2 resolution = vec2(640.0, 480.0); // Virtual resolution (e.g., 640x480)
+uniform sampler2D u_texture;     // Input texture
+uniform vec2 flip = vec2(0.0, 0.0); // UV flip control (0,1 = flip Y)
+
+// Signal mode: 0 = S-Video, 1 = Composite, 2 = CGA Composite
+// Can be changed at runtime without recompilation
+uniform int signalMode = 1;      // Default should be 1 for composite
+
+// CGA-specific settings
+uniform float cgaHue;            // Hue adjustment for CGA (default: 0.0, range: -PI to PI)
+uniform float cgaSaturation;     // Saturation multiplier for CGA (default: 1.0)
+
+// Optional adjustable parameters (set reasonable defaults if not provided)
+uniform float lumaFilterWidth;   // Default: 1.5
+uniform float chromaIFilterWidth; // Default: 3.5
+uniform float chromaQFilterWidth; // Default: 6.0
+uniform float compositeFilterWidth; // Default: 1.5
+uniform float phosphorIntensity; // Default: 0.25
+uniform float scanlineIntensity; // Default: 0.12
+
+in vec2 v_texCoords;
+out vec4 fragColor;
+
+// === CONSTANTS ===
+const float PI = 3.14159265358979323846;
+const float TAU = 6.28318530717958647692;
+
+// NTSC color subcarrier: 3.579545 MHz
+// At 640 pixels for ~52.6µs active video: cycles/pixel ≈ 0.2917
+const float CC_PER_PIXEL = 0.2917;
+
+// CGA specific: 14.318 MHz pixel clock = exactly 4× color subcarrier
+// This means exactly 4 pixels per color cycle = 0.25 cycles per pixel
+const float CGA_CC_PER_PIXEL = 0.25;
+
+// Filter kernel radius (samples to each side)
+const int FILTER_RADIUS = 12;
+
+// === COLOR SPACE CONVERSION ===
+// GLSL matrices are column-major
+const mat3 RGB_TO_YIQ = mat3(
+0.299,  0.596,  0.211,     // Column 0: R coefficients for Y,I,Q
+0.587, -0.274, -0.523,     // Column 1: G coefficients
+0.114, -0.322,  0.312      // Column 2: B coefficients
+);
+
+const mat3 YIQ_TO_RGB = mat3(
+1.000,  1.000,  1.000,     // Column 0: Y coefficients for R,G,B
+0.956, -0.272, -1.107,     // Column 1: I coefficients
+0.621, -0.647,  1.704      // Column 2: Q coefficients
+);
+
+// === DEFAULT VALUES ===
+// Used when uniforms aren't set (value of 0)
+float getLumaFilter() {
+    return lumaFilterWidth > 0.0 ? lumaFilterWidth : 1.15;
+}
+float getChromaIFilter() {
+    return chromaIFilterWidth > 0.0 ? chromaIFilterWidth : 3.5;
+}
+float getChromaQFilter() {
+    return chromaQFilterWidth > 0.0 ? chromaQFilterWidth : 6.0;
+}
+float getCompositeFilter() {
+    return compositeFilterWidth > 0.0 ? compositeFilterWidth : 1.35;
+}
+float getPhosphorStrength() {
+    return phosphorIntensity > 0.0 ? phosphorIntensity : 0.25;
+}
+float getScanlineStrength() {
+    return scanlineIntensity > 0.0 ? scanlineIntensity : 0.12;
+}
+float getCgaSaturation() {
+    return cgaSaturation > 0.0 ? cgaSaturation : 1.0;
+}
+
+// === HELPER FUNCTIONS ===
+
+float gaussianWeight(float x, float sigma) {
+    return exp(-0.5 * x * x / (sigma * sigma));
+}
+
+vec3 sampleTexture(vec2 uv) {
+    return texture(u_texture, clamp(uv, 0.0, 1.0)).rgb;
+}
+
+float calcCarrierPhase(float pixelX, float pixelY, float frameOffset) {
+    float phase = pixelX * TAU * CC_PER_PIXEL;
+    phase += pixelY * PI;  // 180° per line (from 227.5 cycles/line)
+    phase += frameOffset;
+    return phase;
+}
+
+float encodeComposite(vec3 rgb, float phase) {
+    vec3 yiq = RGB_TO_YIQ * rgb;
+    return yiq.x + yiq.y * cos(phase) + yiq.z * sin(phase);
+}
+
+// === COMPOSITE SIGNAL DECODE ===
+vec3 decodeComposite(vec2 uv, vec2 texelSize, float basePhase) {
+    float compFilter = getCompositeFilter();
+    float iFilter = getChromaIFilter();
+    float qFilter = getChromaQFilter();
+
+    float yAccum = 0.0, iAccum = 0.0, qAccum = 0.0;
+    float yWeight = 0.0, iWeight = 0.0, qWeight = 0.0;
+
+    for (int i = -FILTER_RADIUS; i <= FILTER_RADIUS; i++) {
+        float offset = float(i);
+        vec2 sampleUV = uv + vec2(offset * texelSize.x, 0.0);
+
+        vec3 srcRGB = sampleTexture(sampleUV);
+        float samplePhase = basePhase + offset * TAU * CC_PER_PIXEL;
+        float composite = encodeComposite(srcRGB, samplePhase);
+
+        // Low-pass for luma
+        float yw = gaussianWeight(offset, compFilter);
+        yAccum += composite * yw;
+        yWeight += yw;
+
+        // Demodulate and filter chroma
+        float iw = gaussianWeight(offset, iFilter);
+        float qw = gaussianWeight(offset, qFilter);
+
+        iAccum += composite * cos(samplePhase) * 2.0 * iw;
+        qAccum += composite * sin(samplePhase) * 2.0 * qw;
+
+        iWeight += iw;
+        qWeight += qw;
+    }
+
+    vec3 yiq = vec3(yAccum / yWeight, iAccum / iWeight, qAccum / qWeight);
+    return YIQ_TO_RGB * yiq;
+}
+
+// === S-VIDEO SIGNAL DECODE ===
+vec3 decodeSVideo(vec2 uv, vec2 texelSize, float basePhase) {
+    float yFilter = getLumaFilter();
+    float iFilter = getChromaIFilter();
+    float qFilter = getChromaQFilter();
+
+    float yAccum = 0.0, iAccum = 0.0, qAccum = 0.0;
+    float yWeight = 0.0, iWeight = 0.0, qWeight = 0.0;
+
+    for (int i = -FILTER_RADIUS; i <= FILTER_RADIUS; i++) {
+        float offset = float(i);
+        vec2 sampleUV = uv + vec2(offset * texelSize.x, 0.0);
+
+        vec3 srcRGB = sampleTexture(sampleUV);
+        vec3 yiq = RGB_TO_YIQ * srcRGB;
+
+        float samplePhase = basePhase + offset * TAU * CC_PER_PIXEL;
+        float chromaSignal = yiq.y * cos(samplePhase) + yiq.z * sin(samplePhase);
+
+        // Luma is separate - no cross-color
+        float yw = gaussianWeight(offset, yFilter);
+        yAccum += yiq.x * yw;
+        yWeight += yw;
+
+        // Chroma demodulation
+        float iw = gaussianWeight(offset, iFilter);
+        float qw = gaussianWeight(offset, qFilter);
+
+        iAccum += chromaSignal * cos(samplePhase) * 2.0 * iw;
+        qAccum += chromaSignal * sin(samplePhase) * 2.0 * qw;
+
+        iWeight += iw;
+        qWeight += qw;
+    }
+
+    vec3 yiqOut = vec3(yAccum / yWeight, iAccum / iWeight, qAccum / qWeight);
+    return YIQ_TO_RGB * yiqOut;
+}
+
+// === CGA COMPOSITE DECODE ===
+// CGA has exactly 4 pixels per color cycle (14.318 MHz / 3.579545 MHz = 4)
+// This creates the famous artifact colors from specific bit patterns
+vec3 decodeCGAComposite(vec2 uv, vec2 texelSize, float pixelX, float pixelY) {
+    // CGA-specific filter widths - slightly different from generic NTSC
+    // CGA monitors typically had less filtering, making artifacts more pronounced
+    float yFilter = 1.2;
+    float chromaFilter = 2.5;
+
+    // CGA color burst phase - this determines the base hue
+    // Adjusted to match the canonical CGA artifact color palette
+    float cgaPhaseOffset = cgaHue + PI * 0.5;  // Adjust for correct color alignment
+
+    // CGA doesn't have the 227.5 cycle per line offset in the same way
+    // The phase is more deterministic based on pixel position
+    float basePhase = pixelX * TAU * CGA_CC_PER_PIXEL + cgaPhaseOffset;
+
+    // Odd lines have 180° phase shift (creates the alternating pattern)
+    if (mod(pixelY, 2.0) >= 1.0) {
+        basePhase += PI;
+    }
+
+    float yAccum = 0.0, iAccum = 0.0, qAccum = 0.0;
+    float yWeight = 0.0, chromaWeight = 0.0;
+
+    // Use smaller filter radius for sharper CGA look
+    const int CGA_RADIUS = 8;
+
+    for (int i = -CGA_RADIUS; i <= CGA_RADIUS; i++) {
+        float offset = float(i);
+        vec2 sampleUV = uv + vec2(offset * texelSize.x, 0.0);
+
+        // CGA outputs either black (0) or white (1) in 640x200 mode
+        // Get the source value (treating as monochrome for artifact generation)
+        vec3 srcRGB = sampleTexture(sampleUV);
+        float srcLuma = dot(srcRGB, vec3(0.299, 0.587, 0.114));
+
+        // For CGA artifact colors, we use the luma as the composite signal level
+        // In reality, CGA outputs either 0V or ~0.7V for the two states
+        float composite = srcLuma;
+
+        float samplePhase = basePhase + offset * TAU * CGA_CC_PER_PIXEL;
+
+        // Low-pass filter for luma
+        float yw = gaussianWeight(offset, yFilter);
+        yAccum += composite * yw;
+        yWeight += yw;
+
+        // Demodulate chroma
+        float cw = gaussianWeight(offset, chromaFilter);
+        iAccum += composite * cos(samplePhase) * 2.0 * cw;
+        qAccum += composite * sin(samplePhase) * 2.0 * cw;
+        chromaWeight += cw;
+    }
+
+    float y = yAccum / yWeight;
+    float i = (iAccum / chromaWeight) * getCgaSaturation();
+    float q = (qAccum / chromaWeight) * getCgaSaturation();
+
+    // Convert to RGB
+    vec3 rgb = YIQ_TO_RGB * vec3(y, i, q);
+
+    return rgb;
+}
+
+// === TRINITRON PHOSPHOR MASK ===
+vec3 trinitronMask(vec2 screenPos) {
+    float strength = getPhosphorStrength();
+    float outputX = screenPos.x * 2.0;  // 2x display scale
+    float stripe = mod(outputX, 3.0);
+
+    float bleed = 0.15;
+    vec3 mask;
+
+    if (stripe < 1.0) {
+        mask = vec3(1.0, bleed, bleed);
+    } else if (stripe < 2.0) {
+        mask = vec3(bleed, 1.0, bleed);
+    } else {
+        mask = vec3(bleed, bleed, 1.0);
+    }
+
+    float compensation = 1.0 / (0.333 + 0.667 * bleed);
+    mask *= compensation * 0.85;
+
+    return mix(vec3(1.0), mask, strength);
+}
+
+// === SCANLINE MASK ===
+float scanlineMask(vec2 screenPos) {
+    float strength = getScanlineStrength();
+    float outputY = screenPos.y * 2.0;  // 2x display scale
+
+    float scanline = sin(outputY * PI);
+    scanline = scanline * 0.5 + 0.5;
+    scanline = pow(scanline, 0.4);
+
+    return mix(1.0 - strength, 1.0, scanline);
+}
+
+// === MAIN ===
+void main() {
+    vec2 uv = v_texCoords;
+    uv.x = mix(uv.x, 1.0 - uv.x, flip.x);
+    uv.y = mix(uv.y, 1.0 - uv.y, flip.y);
+
+    vec2 texelSize = 1.0 / resolution;
+    float pixelX = uv.x * resolution.x;
+    float pixelY = uv.y * resolution.y;
+
+    // Frame phase for dot crawl (4-frame cycle)
+    float framePhase = mod(time, 4.0) * PI * 0.5;
+    float basePhase = calcCarrierPhase(pixelX, pixelY, framePhase);
+
+    // Decode signal based on mode
+    vec3 rgb;
+    if (signalMode == 2) {
+        // CGA Composite mode - deterministic artifact colors
+        rgb = decodeCGAComposite(uv, texelSize, pixelX, pixelY);
+    } else if (signalMode == 1) {
+        rgb = decodeComposite(uv, texelSize, basePhase);
+    } else {
+        rgb = decodeSVideo(uv, texelSize, basePhase);
+    }
+
+    // CRT display effects
+    vec2 screenPos = vec2(pixelX, pixelY);
+//    rgb *= trinitronMask(screenPos);
+//    rgb *= scanlineMask(screenPos);
+
+    fragColor = vec4(clamp(rgb, 0.0, 1.0), 1.0);
+}
diff --git a/tsvm_executable/src/net/torvald/tsvm/VMGUI.kt b/tsvm_executable/src/net/torvald/tsvm/VMGUI.kt
index 6e9ca76..32c46c1 100644
--- a/tsvm_executable/src/net/torvald/tsvm/VMGUI.kt
+++ b/tsvm_executable/src/net/torvald/tsvm/VMGUI.kt
@@ -97,7 +97,7 @@ class VMGUI(val loaderInfo: EmulInstance, val viewportWidth: Int, val viewportHe
         camera.update()
         batch.projectionMatrix = camera.combined
 
-        crtShader = loadShaderInline(CRT_POST_SHADER2)
+        crtShader = loadShaderInline(Gdx.files.classpath("net/torvald/tsvm/shader_crt_post.frag").readString())
 
         gpuFBO = FrameBuffer(Pixmap.Format.RGBA8888, viewportWidth, viewportHeight, false)
         winFBO = FrameBuffer(Pixmap.Format.RGBA8888, viewportWidth, viewportHeight, false)
@@ -556,200 +556,3 @@ void main() {
 }
 
 """
-
-const val CRT_POST_SHADER2 = """
-#ifdef GL_ES
-precision mediump float;
-#endif
-
-in vec4 v_color;
-in vec4 v_generic;
-in vec2 v_texCoords;
-uniform sampler2D u_texture;
-uniform vec2 resolution = vec2(640.0, 480.0);
-out vec4 fragColor;
-
-uniform float time = 0.0;
-
-const int SUBS = 6;          // horizontal subsamples per pixel (oversampling)
-const float PI = 3.14159265359;
-
-// --- RGB <-> YIQ (NTSC-ish) ---
-vec3 rgb2yiq(vec3 rgb) {
-    float y = dot(rgb, vec3(0.299, 0.587, 0.114));
-    float i = dot(rgb, vec3(0.596, -0.274, -0.322));
-    float q = dot(rgb, vec3(0.211, -0.523, 0.312));
-    return vec3(y, i, q);
-}
-
-vec3 yiq2rgb(vec3 yiq) {
-    float y = yiq.x, i = yiq.y, q = yiq.z;
-    vec3 r = vec3(
-        y + 0.956*i + 0.621*q,
-        y - 0.272*i - 0.647*q,
-        y - 1.106*i + 1.703*q
-    );
-    return clamp(r, 0.0, 1.0);
-}
-
-// --- Parameters you can tweak ---
-float subcarrierCyclesPerScanline = 227.5; // NTSC approx cycles per scanline (spatial)
-float chromaGain = 2.2;        // strength of chroma modulation in encode
-float chromaLPF_radius = 3.6;  // lowpass radius in pixels for chroma (larger = more bleed)
-float lumaLPF_radius  = 0.7;  // lowpass for luma (small = sharp)
-float chromaPhaseDrift = 1.1;  // extra phase offset (use time to animate dot crawl)
-float subsampleSpanPixels = 2.0 / 3.0; // how wide the subsample footprint is (in pixels)
-
-// Simple 1D gaussian weight (not normalized here)
-float gaussWeight(float x, float r) {
-    return exp(- (x*x) / (2.0 * r * r));
-}
-
-// Sample a tiny neighborhood and get averaged Y/I/Q and also do composite modulation
-// We oversample horizontally to simulate the analog sampling along the scanline.
-void compositeAtUV(in vec2 uv, out float avgComposite, out float avgY, out float avgDemodI, out float avgDemodQ) {
-    avgComposite = 0.0;
-    avgY = 0.0;
-    avgDemodI = 0.0;
-    avgDemodQ = 0.0;
-
-    // pixel coordinates
-    float px = uv.x * resolution.x;
-    float py = uv.y * resolution.y;
-    // subcarrier spatial frequency (cycles per pixel horizontally)
-    // cycles per scanline / pixels per scanline = cycles per pixel (approx)
-    float cycles_per_pixel = subcarrierCyclesPerScanline / resolution.x;
-    // time-varying phase for dot-crawl
-    float linePhase = (py * subcarrierCyclesPerScanline) * 2.0 * PI + chromaPhaseDrift * time;
-
-    // do SUBS evenly-spaced subsamples across this pixel horizontally
-    float totalWeight = 0.0;
-    for (int s = 0; s < SUBS; ++s) {
-        float t = (float(s) + 0.5) / float(SUBS) - 0.5; // -0.5 .. +0.5
-        float sx = px + t * subsampleSpanPixels;       // sample x in pixel space
-        vec2 sUV = vec2(sx / resolution.x, uv.y);
-
-        vec3 col = texture2D(u_texture, sUV).rgb;
-        vec3 yiq = rgb2yiq(col);
-        float Y = yiq.x;
-        float I = yiq.y;
-        float Q = yiq.z;
-
-        // subcarrier phase at this horizontal sample
-        float phi = linePhase + sx * cycles_per_pixel * 2.0 * PI;
-
-        // composite waveform value (analog mix)
-        float carrierCos = cos(phi);
-        float carrierSin = sin(phi);
-        float composite = Y + chromaGain * (I * carrierCos + Q * carrierSin);
-
-        // demodulation multipliers (we will low-pass by averaging)
-        float demodI = composite * carrierCos;
-        float demodQ = composite * carrierSin;
-
-        // weight: use gaussian centered on pixel center
-        float w = gaussWeight(t * subsampleSpanPixels, 0.6); // narrower weighting
-        totalWeight += w;
-
-        avgComposite += composite * w;
-        avgY += Y * w;
-        avgDemodI += demodI * w;
-        avgDemodQ += demodQ * w;
-    }
-
-    // normalize the local averages (this approximates a basic low-pass)
-    avgComposite /= totalWeight;
-    avgY /= totalWeight;
-    avgDemodI /= totalWeight;
-    avgDemodQ /= totalWeight;
-
-    // --- additional spatial low-pass filtering to mimic channel bandwidth ---
-    // We'll sample neighbours on x and average with Gaussian weights to emulate chroma/luma LPF
-    // Note: we do a tiny neighborhood (±2 pixels) to save performance.
-    float wsumC = 1.0;
-    float wsumY = 1.0;
-    float csum = avgComposite;
-    float idsum = avgDemodI;
-    float qdsum = avgDemodQ;
-    float ysum = avgY;
-
-    // radius in pixels for chroma or luma affects weights below; we'll use same kernel but scale contributions
-    int taps = 2;
-    for (int i = -taps; i <= taps; ++i) {
-        if (i == 0) continue;
-        float off = float(i);
-        // use chroma radius for chroma-related weights, luma radius for luma
-        float weightC = gaussWeight(off, chromaLPF_radius);
-        float weightY = gaussWeight(off, lumaLPF_radius);
-
-        vec2 sampleUV = vec2((px + off) / resolution.x, uv.y);
-        vec3 ncol = texture2D(u_texture, sampleUV).rgb;
-        vec3 nyiq = rgb2yiq(ncol);
-        float nY = nyiq.x;
-        float nI = nyiq.y;
-        float nQ = nyiq.z;
-
-        float nPhi = linePhase + (px + off) * cycles_per_pixel * 2.0 * PI;
-        float nComposite = nY + chromaGain * (nI * cos(nPhi) + nQ * sin(nPhi));
-        float ndemodI = nComposite * cos(nPhi);
-        float ndemodQ = nComposite * sin(nPhi);
-
-        csum += nComposite * weightC;
-        idsum += ndemodI * weightC;
-        qdsum += ndemodQ * weightC;
-        wsumC += weightC;
-
-        ysum += nY * weightY;
-        wsumY += weightY;
-    }
-
-    avgComposite = csum / wsumC;
-    avgY = ysum / wsumY;
-    avgDemodI = idsum / wsumC;
-    avgDemodQ = qdsum / wsumC;
-}
-
-// main
-void mainImage(out vec4 frag_Color, in vec2 frag_Coord) {
-    vec2 uv = frag_Coord.xy / resolution.xy;
-    uv.y = 1.0 - uv.y;
-
-    // Get composite and demod values centered at uv
-    float compositeVal, Yval, demodI, demodQ;
-    compositeAtUV(uv, compositeVal, Yval, demodI, demodQ);
-
-    // Low-pass the demodulators to extract I & Q (simple normalization)
-    // In a real demodulator you'd low-pass filter demod*carrier; here we've already averaged spatially,
-    // so just apply a gain normalization and small smoothing.
-    // Normalize I/Q by average carrier power (~0.5)
-    float carrierPower = 0.5;
-    float I_rec = demodI / max(carrierPower, 1e-5);
-    float Q_rec = demodQ / max(carrierPower, 1e-5);
-
-    // Optionally reduce chroma bandwidth / smear by blurring (simulate narrow chroma filter)
-    // We'll lerp the recovered chroma towards zero based on chromaLPF_radius
-    float chromaBlurFactor = smoothstep(0.0, 5.0, chromaLPF_radius); // 0..1
-    I_rec *= 1.0 - 0.65 * chromaBlurFactor;
-    Q_rec *= 1.0 - 0.65 * chromaBlurFactor;
-
-    // For luma, we can optionally low-pass Yval slightly to simulate limited luma bandwidth
-    // but keep it mostly sharp
-    float Y_lp = Yval; // already lightly filtered above
-    // final reconstructed yiq
-    vec3 yiqRec = vec3(Y_lp, I_rec, Q_rec);
-    vec3 rgbRec = yiq2rgb(yiqRec);
-
-    // Optional: blend with original luminance to keep text legible (tweakable)
-    // vec3 orig = texture2D(u_texture, uv).rgb;
-    // rgbRec = mix(rgbRec, orig, 0.25);
-
-    frag_Color = vec4(rgbRec, 1.0);
-}
-
-void main() {
-    vec2 fragCoord = gl_FragCoord.xy;
-    vec4 outcol;
-    mainImage(outcol, fragCoord);
-    fragColor = outcol;
-}
-"""
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