data storage

shaders/feedback-highlight-accumulator/shader.json

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+{
+  "id": "feedback-highlight-accumulator",
+  "name": "Feedback Highlight Accumulator",
+  "description": "Demonstrates shader-local feedback by accumulating only the brightest-looking parts of the image over a timed window, then resetting and starting again. The highlight selection is an approximation based on a luminance threshold rather than an exact percentile reduction.",
+  "category": "Feedback",
+  "entryPoint": "shadeVideo",
+  "feedback": {
+    "enabled": true
+  },
+  "parameters": [
+    {
+      "id": "highlightThreshold",
+      "label": "Highlight Threshold",
+      "type": "float",
+      "default": 0.99,
+      "min": 0.5,
+      "max": 1.5,
+      "step": 0.001,
+      "description": "Approximate cutoff for the brightest parts of the frame."
+    },
+    {
+      "id": "softness",
+      "label": "Threshold Softness",
+      "type": "float",
+      "default": 0.05,
+      "min": 0.001,
+      "max": 0.25,
+      "step": 0.001,
+      "description": "Softens the threshold so near-highlights can contribute gradually."
+    },
+    {
+      "id": "accumulateAmount",
+      "label": "Accumulate Amount",
+      "type": "float",
+      "default": 0.2,
+      "min": 0.0,
+      "max": 2.0,
+      "step": 0.001,
+      "description": "How much of each bright sample gets added into the running feedback image."
+    },
+    {
+      "id": "displayGain",
+      "label": "Display Gain",
+      "type": "float",
+      "default": 1.0,
+      "min": 0.0,
+      "max": 4.0,
+      "step": 0.01,
+      "description": "Brightness applied to the accumulated feedback when displayed."
+    },
+    {
+      "id": "baseMix",
+      "label": "Base Mix",
+      "type": "float",
+      "default": 0.25,
+      "min": 0.0,
+      "max": 1.0,
+      "step": 0.01,
+      "description": "Amount of the live source image kept under the accumulation."
+    },
+    {
+      "id": "resetSeconds",
+      "label": "Reset Seconds",
+      "type": "float",
+      "default": 10.0,
+      "min": 1.0,
+      "max": 60.0,
+      "step": 0.1,
+      "description": "Length of each accumulation window before the feedback resets."
+    }
+  ]
+}

shaders/feedback-highlight-accumulator/shader.slang

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+float luminance(float3 color)
+{
+    return dot(color, float3(0.2126, 0.7152, 0.0722));
+}
+
+float currentResetPhase(float timeSeconds, float resetInterval)
+{
+    float safeInterval = max(resetInterval, 0.001);
+    float cycleIndex = floor(timeSeconds / safeInterval);
+    return frac(cycleIndex * 0.5) >= 0.5 ? 1.0 : 0.0;
+}
+
+float4 shadeVideo(ShaderContext context)
+{
+    float safeResetSeconds = max(resetSeconds, 0.001);
+    float phase = currentResetPhase(context.time, safeResetSeconds);
+
+    float4 previousFeedback = sampleFeedback(context.uv);
+    bool phaseMatches = context.feedbackAvailable > 0 && abs(previousFeedback.a - phase) < 0.25;
+    float3 previousAccumulation = phaseMatches ? previousFeedback.rgb : float3(0.0, 0.0, 0.0);
+
+    float currentLuma = luminance(context.sourceColor.rgb);
+    float thresholdWidth = max(softness, 0.0001);
+    float brightMask = smoothstep(highlightThreshold - thresholdWidth, highlightThreshold + thresholdWidth, currentLuma);
+
+    float3 currentContribution = context.sourceColor.rgb * brightMask * max(accumulateAmount, 0.0);
+    float3 nextAccumulation = saturate(previousAccumulation + currentContribution);
+
+    float3 displayColor = context.sourceColor.rgb * saturate(baseMix) + nextAccumulation * max(displayGain, 0.0);
+    return float4(saturate(displayColor), phase);
+}