Multi pass test

shaders/gaussian-blur/shader.json

@@ -1,9 +1,25 @@
 {
   "id": "gaussian-blur",
   "name": "Gaussian Blur",
-  "description": "Applies a simple Gaussian-style blur to the decoded video input.",
+  "description": "Applies a separable two-pass Gaussian-style blur to the decoded video input.",
   "category": "Transform",
   "entryPoint": "shadeVideo",
+  "passes": [
+    {
+      "id": "horizontal",
+      "source": "shader.slang",
+      "entryPoint": "blurHorizontal",
+      "inputs": ["layerInput"],
+      "output": "blurHorizontal"
+    },
+    {
+      "id": "vertical",
+      "source": "shader.slang",
+      "entryPoint": "blurVertical",
+      "inputs": ["blurHorizontal"],
+      "output": "layerOutput"
+    }
+  ],
   "parameters": [
     {
       "id": "radius",

shaders/gaussian-blur/shader.slang

@@ -1,25 +1,22 @@
-float4 shadeVideo(ShaderContext context)
+float4 gaussianBlurDirection(ShaderContext context, float2 direction)
 {
 	float2 texel = 1.0 / max(context.inputResolution, float2(1.0, 1.0));
-	float blurRadius = max(radius, 0.0);
-	float2 sampleStep = texel * blurRadius;
+	float blurRadius = max(radius, 0.0) * saturate(strength);
+	float2 sampleStep = texel * blurRadius * direction;
 	int sampleRadius = int(clamp(samples, 0.0, 8.0) + 0.5);
 
 	float4 center = sampleVideo(context.uv);
 	float4 blur = float4(0.0, 0.0, 0.0, 0.0);
 	float totalWeight = 0.0;
 
-	for (int y = -sampleRadius; y <= sampleRadius; ++y)
+	for (int x = -sampleRadius; x <= sampleRadius; ++x)
 	{
-		for (int x = -sampleRadius; x <= sampleRadius; ++x)
-		{
-			float distanceSquared = float(x * x + y * y);
-			float sigma = max(float(sampleRadius) * 0.5, 0.5);
-			float weight = exp(-distanceSquared / (2.0 * sigma * sigma));
-			float2 offset = float2(float(x), float(y)) * sampleStep;
-			blur += sampleVideo(context.uv + offset) * weight;
-			totalWeight += weight;
-		}
+		float distanceSquared = float(x * x);
+		float sigma = max(float(sampleRadius) * 0.5, 0.5);
+		float weight = exp(-distanceSquared / (2.0 * sigma * sigma));
+		float2 offset = float(x) * sampleStep;
+		blur += sampleVideo(context.uv + offset) * weight;
+		totalWeight += weight;
 	}
 
 	if (sampleRadius == 0)
@@ -29,7 +26,20 @@ float4 shadeVideo(ShaderContext context)
 	}
 
 	blur /= max(totalWeight, 0.0001);
-
-	float mixValue = saturate(strength);
-	return lerp(center, blur, mixValue);
+	return blur;
+}
+
+float4 blurHorizontal(ShaderContext context)
+{
+	return gaussianBlurDirection(context, float2(1.0, 0.0));
+}
+
+float4 blurVertical(ShaderContext context)
+{
+	return gaussianBlurDirection(context, float2(0.0, 1.0));
+}
+
+float4 shadeVideo(ShaderContext context)
+{
+	return blurVertical(context);
 }