Storing the current eye id in the context so that we can use it in autoexposure.

Author: fcoulombe

com.unity.postprocessing/PostProcessing/Runtime/Effects/AutoExposure.cs

@@ -122,7 +122,7 @@ void CheckTexture(int eye, int id)
         public override void Render(PostProcessRenderContext context)
         {
             // multi pass and singlepass only has a single eye
-            int eye = (context.numberOfEyes>1) ? context.xrActiveEye : 0;
+            int eye = context.currentEye;
             var cmd = context.command;
             cmd.BeginSample("AutoExposureLookup");
 

com.unity.postprocessing/PostProcessing/Runtime/PostProcessLayer.cs

@@ -1182,6 +1182,7 @@ int RenderBuiltins(PostProcessRenderContext context, bool isFinalPass, int relea
             context.uberSheet = uberSheet;
             context.autoExposureTexture = RuntimeUtilities.whiteTexture;
             context.bloomBufferNameID = -1;
+            context.currentEye = eye;
 
             if (isFinalPass && context.stereoActive && context.stereoRenderingMode == PostProcessRenderContext.StereoRenderingMode.SinglePassInstanced)
                 uberSheet.EnableKeyword("STEREO_INSTANCING_ENABLED");

com.unity.postprocessing/PostProcessing/Runtime/PostProcessRenderContext.cs

@@ -144,6 +144,13 @@ public Camera camera
         /// </summary>
         public int xrActiveEye { get; private set; }
 
+        /// <summary>
+        /// The xrActiveEye is not necessarily the right eye id depending which mode we're running on.
+        /// The renderbuiltin function receives an eye id. This eye id gets stored here during the current
+        /// eye.
+        /// </summary>
+        internal int currentEye = 0;
+
         /// <summary>
         /// The number of eyes for XR outputs.
         /// </summary>