I’m developing a VR application using Unreal Engine 5, HTC Vive and the Wave VR plugin, where you can paint on a wall with a spray can.
I basically used these two videos for it and built a mixture of both:
Paint Canvas in VR
Drawing on Surfaces in Virtual Reality
As I understood it, I basically use a line tracing to check where the spray can touches the canvas and add a “color material” to the canvas wall material at that point, creating a color dot at that point. With mobile HDR turned on, this all works fine, but as soon as I export the game for the VIVE and start it, I get an additional 2D window on the left edge of the VR Field of view that shows again the camera view. It seems a bit like a mirror display or something similar? Very irritating that it’s inside of the application. The only way I found to get rid of this is to turn Mobile HDR off and Mobile Multi-View on in the project settings.
The problem is, as soon as I do that, my painted color gets mirrored. When I point at the wall and paint up, the stroke on the canvas goes down and the other way around. Right and left is still correct though. When I turn Mobile HDR back on, everything works as before. Visualized the trace line, it’s acting normal and hitting the canvas at the wanted spot. I have a bit of a feeling that turning off Mobile HDR rotates the UV coordinates or smth? But I don’t know how to rotate them back. I tried, at the point where the hitpoint is transferred to the UV coordinates, to multiply it with a (1,-1) vector. But that absolutely does not work either.
Does anyone have any idea what the problem could be with this, why the material on the render target gets mirrored? Oh yeah, that also just happens in exported VR. When I try it in the engine by simply moving the spraying can across the wall using the X, Y and Z coordinates everything acts normal 
Or does anyone know how to get rid of this mirror display in the application with Mobile HDR turned on? I am losing my mind at this point…