Fixed: use signed integer for distortion

ScriptableRenderPipeline/HDRenderPipeline/Material/Builtin/BuiltinData.hlsl

     // RT - 16:16:16:16 float
     // distortionBlur in alpha for a different blend mode
     // Tag pixel as a pixel that can be used as source for distortion (b != 0)
-    // It is compatible with blend mode: either Add or Multiply
+    // It is compatible with Add blend mode (a pixel cannot be a valid distortion source only if there is no distorting object in front of it)
     outBuffer = float4(distortion, validSourceForDistortion ? 1.0 : 0.0, distortionBlur);
 }
 
     distortionBlur = inBuffer.a;
-    validSourceForDistortion = inBuffer.z > 0.1 || inBuffer.z < 0.1;
+    validSourceForDistortion = inBuffer.z != 0.0;
 }
 
 void GetBuiltinDataDebug(uint paramId, BuiltinData builtinData, inout float3 result, inout bool needLinearToSRGB)

ScriptableRenderPipeline/HDRenderPipeline/RenderPipelineResources/ApplyDistorsion.compute

     DecodeDistortion(encodedDistortion, distortion, distortionBlur, validForDistortion);
 
     // Get distortion source pixel mask (stored in _DistortionTexture.z)
-    uint2 distortedEncodedDistortionId = dispatchThreadId + uint2(distortion);
+    uint2 distortedEncodedDistortionId = dispatchThreadId + int2(distortion);
 
     float2 distordedDistortion;
     float2 distordedDistortionBlur;
     if (distordedValidForDistortion && validForDistortion)
     {
         // Get source pixel for distortion
-        float2 distordedUV = float2(dispatchThreadId + uint2(distortion * _FetchBias)) * _Size.zw;
+        float2 distordedUV = float2(dispatchThreadId + int2(distortion * _FetchBias)) * _Size.zw;
         float mip = (_GaussianPyramidColorMipSize.z - 1) * clamp(distortionBlur.x, 0.0, 1.0);
         float4 sampled = _GaussianPyramidColorTexture.SampleLevel(sampler_GaussianPyramidColorTexture, distordedUV, mip);