Supposted stereo-ized clustered light list lookups

Use the same mechanisms from lightlistbuild-clustered to read from g_vLayeredOffsetsBuffer and g_logBaseBuffer

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightLoop/LightLoopDef.hlsl

 // these uniforms are only needed for when OPAQUES_ONLY is NOT defined
 // but there's a problem with our front-end compilation of compute shaders with multiple kernels causing it to error
 //#ifdef USE_CLUSTERED_LIGHTLIST
-float4x4 g_mInvScrProjection;
+float4x4 g_mInvScrProjection; // TODO: remove, unused in HDRP
 
 float g_fClustScale;
 float g_fClustBase;
 TEXTURE2D_ARRAY(_Env2DTextures);
 float4x4 _Env2DCaptureVP[MAX_ENV2D_LIGHT];
 
+// XRTODO: Need to stereo-ize access
 TEXTURE2D(_DeferredShadowTexture);
 
 CBUFFER_START(UnityPerLightLoop)
     float logBase = g_fClustBase;
     if (g_isLogBaseBufferEnabled)
     {
+        // XRTODO: Stereo-ize access to g_logBaseBuffer
         logBase = g_logBaseBuffer[tileIndex.y * _NumTileClusteredX + tileIndex.x];
     }
 
     float logBase = g_fClustBase;
     if (g_isLogBaseBufferEnabled)
     {
-        logBase = g_logBaseBuffer[tileIndex.y * _NumTileClusteredX + tileIndex.x];
+        // XRTODO - DONE: Stereo-ize access to g_logBaseBuffer
+        const uint eyeOffset = unity_StereoEyeIndex * _NumTileClusteredX * _NumTileClusteredY;
+        logBase = g_logBaseBuffer[eyeOffset + (tileIndex.y * _NumTileClusteredX) + tileIndex.x];
     }
 
     return SnapToClusterIdxFlex(linearDepth, logBase, g_isLogBaseBufferEnabled != 0);
 {
     int nrClusters = (1 << g_iLog2NumClusters);
-    const int idx = ((lightCategory * nrClusters + clusterIndex) * _NumTileClusteredY + tileIndex.y) * _NumTileClusteredX + tileIndex.x;
+    int idx = ((lightCategory * nrClusters + clusterIndex) * _NumTileClusteredY + tileIndex.y) * _NumTileClusteredX + tileIndex.x;
+    
+    // XRTODO - DONE: Add the eye offset.  Each eye is split into category, cluster, x, y
+    idx += unity_StereoEyeIndex * LIGHTCATEGORY_COUNT * nrClusters * _NumTileClusteredX * _NumTileClusteredY;
+    
     uint dataPair = g_vLayeredOffsetsBuffer[idx];
     start = dataPair & 0x7ffffff;
     lightCount = (dataPair >> 27) & 31;
 {
+    // XRTODO - DONE: Will have to fix up GetLightClusterIndex and GetCountAndStartCluster
+    // basicaly the log base and offset buffers are stereo ized.  depth tex anywhere as well?
+
+    // Note: XR depends on unity_StereoEyeIndex already being defined,
+    // which means ShaderVariables.hlsl needs to be defined ahead of this!
+
     uint2 tileIndex    = posInput.tileCoord;
     uint  clusterIndex = GetLightClusterIndex(tileIndex, posInput.linearDepth);