example data store

shaders/feedback-data-blocks/shader.json

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+{
+  "id": "feedback-data-blocks",
+  "name": "Feedback Data Blocks",
+  "description": "Demonstrates using the feedback surface as coarse data storage by reserving eight 3x3 texel cells for sampled colors and a hidden metadata cell for timed or trigger-driven refresh state.",
+  "category": "Feedback",
+  "entryPoint": "storeProbeData",
+  "passes": [
+    {
+      "id": "store",
+      "source": "shader.slang",
+      "entryPoint": "storeProbeData",
+      "output": "dataBuffer"
+    },
+    {
+      "id": "display",
+      "source": "shader.slang",
+      "entryPoint": "displayProbeData",
+      "inputs": [
+        "dataBuffer"
+      ],
+      "output": "layerOutput"
+    }
+  ],
+  "feedback": {
+    "enabled": true,
+    "writePass": "store"
+  },
+  "parameters": [
+    {
+      "id": "refresh",
+      "label": "Refresh",
+      "type": "trigger",
+      "description": "Forces the stored probe colors to resample immediately."
+    },
+    {
+      "id": "refreshSeconds",
+      "label": "Refresh Seconds",
+      "type": "float",
+      "default": 15.0,
+      "min": 1.0,
+      "max": 60.0,
+      "step": 0.1,
+      "description": "Automatic interval for resampling all stored probe colors."
+    },
+    {
+      "id": "overlayOpacity",
+      "label": "Overlay Opacity",
+      "type": "float",
+      "default": 1.0,
+      "min": 0.0,
+      "max": 1.0,
+      "step": 0.01,
+      "description": "Strength of the swatch overlay drawn from the stored data cells."
+    },
+    {
+      "id": "swatchSize",
+      "label": "Swatch Size",
+      "type": "vec2",
+      "default": [0.045, 0.055],
+      "min": [0.02, 0.02],
+      "max": [0.12, 0.12],
+      "step": [0.001, 0.001],
+      "description": "Size of the top-left preview swatches that show the stored cell values."
+    }
+  ]
+}

shaders/feedback-data-blocks/shader.slang

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+static const int kProbeCount = 8;
+static const int kMetadataIndex = 8;
+
+float2 probeUvForIndex(int index)
+{
+    if (index == 0)
+        return float2(0.18, 0.28);
+    if (index == 1)
+        return float2(0.39, 0.28);
+    if (index == 2)
+        return float2(0.61, 0.28);
+    if (index == 3)
+        return float2(0.82, 0.28);
+    if (index == 4)
+        return float2(0.18, 0.72);
+    if (index == 5)
+        return float2(0.39, 0.72);
+    if (index == 6)
+        return float2(0.61, 0.72);
+    return float2(0.82, 0.72);
+}
+
+float2 cellCenterPixelForIndex(int index)
+{
+    return float2(1.0 + float(index) * 3.0, 1.0);
+}
+
+float2 cellCenterUvForIndex(ShaderContext context, int index)
+{
+    return (cellCenterPixelForIndex(index) + 0.5) / context.outputResolution;
+}
+
+bool pixelIsInsideCell(float2 pixelCoord, int index)
+{
+    float minX = float(index) * 3.0;
+    float maxX = minX + 3.0;
+    return pixelCoord.x >= minX && pixelCoord.x < maxX && pixelCoord.y >= 0.0 && pixelCoord.y < 3.0;
+}
+
+float4 readStoredCell(ShaderContext context, int index)
+{
+    if (context.feedbackAvailable <= 0)
+        return float4(0.0, 0.0, 0.0, 0.0);
+    return sampleFeedback(cellCenterUvForIndex(context, index));
+}
+
+bool shouldRefreshStoredData(ShaderContext context)
+{
+    if (context.feedbackAvailable <= 0)
+        return true;
+
+    float4 metadata = readStoredCell(context, kMetadataIndex);
+    float previousRefreshBucket = metadata.r;
+    float previousTriggerCount = metadata.g;
+    float refreshInterval = max(refreshSeconds, 0.001);
+    float currentRefreshBucket = floor(context.time / refreshInterval);
+    float currentTriggerCount = float(refresh);
+
+    return currentRefreshBucket > previousRefreshBucket + 0.5 || currentTriggerCount > previousTriggerCount + 0.5;
+}
+
+float4 metadataValueForFrame(ShaderContext context, bool refreshNow)
+{
+    float refreshInterval = max(refreshSeconds, 0.001);
+    float currentRefreshBucket = floor(context.time / refreshInterval);
+    float currentTriggerCount = float(refresh);
+
+    if (!refreshNow && context.feedbackAvailable > 0)
+        return readStoredCell(context, kMetadataIndex);
+
+    return float4(currentRefreshBucket, currentTriggerCount, refreshTime, 1.0);
+}
+
+float4 storedProbeValueForFrame(ShaderContext context, int index, bool refreshNow)
+{
+    float3 liveColor = sampleLayerInput(probeUvForIndex(index)).rgb;
+    if (refreshNow || context.feedbackAvailable <= 0)
+        return float4(liveColor, 1.0);
+    return readStoredCell(context, index);
+}
+
+float4 storeProbeData(ShaderContext context)
+{
+    // Reserve nine 3x3 texel cells along the top edge of the feedback surface:
+    // eight cells for visible probe colors and one hidden metadata cell that
+    // tracks the timed refresh bucket and last trigger count.
+    float2 pixelCoord = floor(context.uv * context.outputResolution);
+    bool refreshNow = shouldRefreshStoredData(context);
+
+    for (int index = 0; index < kProbeCount; ++index)
+    {
+        if (pixelIsInsideCell(pixelCoord, index))
+            return storedProbeValueForFrame(context, index, refreshNow);
+    }
+
+    if (pixelIsInsideCell(pixelCoord, kMetadataIndex))
+        return metadataValueForFrame(context, refreshNow);
+
+    return float4(0.0, 0.0, 0.0, 1.0);
+}
+
+float rectMask(float2 uv, float2 minUv, float2 maxUv)
+{
+    if (uv.x < minUv.x || uv.x > maxUv.x)
+        return 0.0;
+    if (uv.y < minUv.y || uv.y > maxUv.y)
+        return 0.0;
+    return 1.0;
+}
+
+float borderMask(float2 uv, float2 minUv, float2 maxUv, float thickness)
+{
+    float outer = rectMask(uv, minUv, maxUv);
+    float inner = rectMask(uv, minUv + thickness, maxUv - thickness);
+    return saturate(outer - inner);
+}
+
+float4 displayProbeData(ShaderContext context)
+{
+    float3 baseColor = sampleLayerInput(context.uv).rgb;
+    float3 swatchColor = baseColor;
+    float swatchMask = 0.0;
+
+    float2 panelOrigin = float2(0.03, 0.04);
+    float2 gap = float2(swatchSize.x + 0.012, swatchSize.y + 0.012);
+    float borderThickness = min(swatchSize.x, swatchSize.y) * 0.08;
+
+    for (int index = 0; index < kProbeCount; ++index)
+    {
+        int column = index % 4;
+        int row = index / 4;
+        float2 swatchMin = panelOrigin + float2(float(column) * gap.x, float(row) * gap.y);
+        float2 swatchMax = swatchMin + swatchSize;
+        float3 storedColor = sampleVideo(cellCenterUvForIndex(context, index)).rgb;
+        float fill = rectMask(context.uv, swatchMin, swatchMax);
+        float outline = borderMask(context.uv, swatchMin, swatchMax, borderThickness);
+        if (fill > 0.5)
+        {
+            swatchColor = storedColor;
+            swatchMask = 1.0;
+        }
+        if (outline > 0.5)
+        {
+            swatchColor = float3(0.0, 0.0, 0.0);
+            swatchMask = 1.0;
+        }
+    }
+
+    float opacity = saturate(overlayOpacity) * swatchMask;
+    float3 displayColor = lerp(baseColor, swatchColor, opacity);
+    return float4(saturate(displayColor), 1.0);
+}