Delay between head tracking and scene render

[rubenquidam]

Objects placed as children of the camera should look static on screen relative to camera motion (or at least that is my interpretation from reading #121). Instead, when a movement is sharp (e.g. tracking error jumps) the children objects can visually jump some amount, this being more noticeable the closest the object is to the camera. It also causes a small visual lag in general, even with smooth movements and no tracking errors. I'm using monado

My application is a quite unusual setup in where I implement a VR headset within the scene (using viewports very close to the cameras), so I can play with parallax, culling, brightness, etc, for behavioral optometry research. The visual jumps and lag are very amplified in my setup so I tried to work around it by updating the positions of the objects that render the viewports, in relation to the hmd global transform, but I haven't found a way to do it early enough and I get tearing.

Is there a way to ensure object positions are current relative to the arvrcamera, before rendering?