Fixed VR single pass rendering and some RT state management.

ScriptableRenderPipeline/LightweightPipeline/LWRP/LightweightPipeline.cs

             base.Dispose();
             Shader.globalRenderPipeline = "";
 
+            SupportedRenderingFeatures.active = new SupportedRenderingFeatures();
+
             CoreUtils.Destroy(m_ErrorMaterial);
             CoreUtils.Destroy(m_CopyDepthMaterial);
             CoreUtils.Destroy(m_BlitMaterial);
             // state is update, causing RenderPostProcess here to not blit to FinalColorRT. Until the next frame the RT will have garbage.
             if (LightweightUtils.HasFlag(config, FrameRenderingConfiguration.BeforeTransparentPostProcess))
             {
-                RenderPostProcess(cmd, m_ColorRT, m_CopyColorRT, true);
-                m_CurrCameraColorRT = (m_IsOffscreenCamera) ? BuiltinRenderTextureType.CameraTarget : m_ColorRT;
+                RenderPostProcess(cmd, m_CurrCameraColorRT, m_CopyColorRT, true);
+                m_CurrCameraColorRT = m_CopyColorRT;
-                RenderTargetIdentifier colorRT = (m_IsOffscreenCamera) ? BuiltinRenderTextureType.CameraTarget : m_ColorRT;
-                SetRenderTarget(cmd, colorRT, m_CopyDepth);
+                SetRenderTarget(cmd, m_CurrCameraColorRT, m_CopyDepth);
             }
 
             context.ExecuteCommandBuffer(cmd);
                 return;
 
             CommandBuffer cmd = CommandBufferPool.Get("After Transparent");
-            RenderPostProcess(cmd, BuiltinRenderTextureType.CurrentActive, BuiltinRenderTextureType.CameraTarget, false);
+            RenderPostProcess(cmd, m_CurrCameraColorRT, BuiltinRenderTextureType.CameraTarget, false);
             context.ExecuteCommandBuffer(cmd);
             CommandBufferPool.Release(cmd);
         }
             var cmd = CommandBufferPool.Get("Blit");
             if (m_IntermediateTextureArray)
             {
-                SetRenderTarget(cmd, BuiltinRenderTextureType.CameraTarget);
-                cmd.Blit(m_CurrCameraColorRT, BuiltinRenderTextureType.CurrentActive);
+                cmd.Blit(m_CurrCameraColorRT, BuiltinRenderTextureType.CameraTarget);
+                Material blitMaterial = m_BlitMaterial;
+                if (LightweightUtils.HasFlag(renderingConfig, FrameRenderingConfiguration.Stereo))
+                    blitMaterial = null;
+
-                    Blit(cmd, renderingConfig, BuiltinRenderTextureType.CurrentActive, BuiltinRenderTextureType.CameraTarget, m_BlitMaterial);
+                    Blit(cmd, renderingConfig, m_CurrCameraColorRT, BuiltinRenderTextureType.CameraTarget, blitMaterial);
             }
 
             SetRenderTarget(cmd, BuiltinRenderTextureType.CameraTarget);
             if (opaqueOnly)
             {
                 m_CameraPostProcessLayer.RenderOpaqueOnly(m_PostProcessRenderContext);
-                cmd.Blit(m_CopyColorRT, m_ColorRT);
             }
             else
                 m_CameraPostProcessLayer.Render(m_PostProcessRenderContext);

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightShaderLibrary/InputBuiltin.hlsl

 #ifndef LIGHTWEIGHT_SHADER_VARIABLES_INCLUDED
 #define LIGHTWEIGHT_SHADER_VARIABLES_INCLUDED
 
+#if (defined(SHADER_API_D3D11)  || defined(SHADER_API_PSSL)) && defined(STEREO_INSTANCING_ON)
+#define UNITY_STEREO_INSTANCING_ENABLED
+#endif
+
 #if defined(UNITY_SINGLE_PASS_STEREO) || defined(UNITY_STEREO_INSTANCING_ENABLED) || defined(UNITY_STEREO_MULTIVIEW_ENABLED)
 #define USING_STEREO_MATRICES
 #endif