Multisampling in OpenXR

[Richtea]

I've been looking into trying to get MSAA antialiasing working within an OpenXR VR application.

I'm looking at how the swapchain images get created

                XrSwapchainCreateInfo swapchainCreateInfo = XrSwapchainCreateInfo.malloc(stack)
                        .type$Default()
                        .next(NULL)
                        .createFlags(0)
                        .usageFlags(XR10.XR_SWAPCHAIN_USAGE_SAMPLED_BIT | XR10.XR_SWAPCHAIN_USAGE_COLOR_ATTACHMENT_BIT)
                        .format(glColorFormat)
                        .sampleCount(viewConfig.recommendedSwapchainSampleCount()) //<--- interesting
                        .width(viewConfig.recommendedImageRectWidth())
                        .height(viewConfig.recommendedImageRectHeight())
                        .faceCount(1)
                        .arraySize(1)
                        .mipCount(1);

                PointerBuffer swapchainHanglePointerBuffer = stack.mallocPointer(1);
                checkResponseCode(XR10.xrCreateSwapchain(xrSession, swapchainCreateInfo, swapchainHanglePointerBuffer));

And looking at where recommendedSwapchainSampleCount comes from it is from asking the runtime for its opinion

            checkResponseCode(XR10.xrEnumerateViewConfigurationViews(xrInstance, systemID, viewConfigType, viewCountPointer, null));
            viewConfigs = XrUtils.fill(
                    XrViewConfigurationView.calloc(viewCountPointer.get(0)), // use calloc() rather than malloc() to ensure the next field is correctly initialized
                    XrViewConfigurationView.TYPE,
                    XR10.XR_TYPE_VIEW_CONFIGURATION_VIEW
            );

            checkResponseCode(XR10.xrEnumerateViewConfigurationViews(xrInstance, systemID, viewConfigType, viewCountPointer, viewConfigs));

And for my system `viewConfig.recommendedSwapchainSampleCount()` returns 1 (And setting anything else gives me a XR_ERROR_RUNTIME_FAILURE error code). But I don't understand why it's 1. My system aught to be able to support more than that (Its all done locally on the PC right, the headsets not doing the sampling right?); in non VR contexts antialiasing all works fine. (viewConfig.maxSwapchainSampleCount() also returns 1)

My system is:
Oculus Quest 2 running over Virtual Desktop
Windows 10
NVidea GeForce RTX 3070


Am I on the right track here? Any ideas as to how I can get MSAA  antialiasing working?

[Richtea]

edit; sorry, some how managed to quote reply myself rather than editing  Please ignore this reply

[Richtea]

I understand now I think. I need to render to a seperate frame buffer (that supports multisampling) then blit into a second frame buffers for OpenXR to use as its swapchain image