How to keep pixels_per_meter in sync with window resize?

[Luminoth]

Is there a best way to keep bevy_rapier's pixels_per_meter sync'd with window resizes when not using ScalingMode::WindowSize ? It seems like pixels_per_meter makes sense when using that scaling mode (the Bevy default) but not when using any of the other scaling modes, which will change the pixels_per_meter every time a resize happens. Or is that something that's already accounted for behind the scenes?

[sebcrozet]

There is no way to change pixels_per_meter after the initialization of the bevy_rapier plugin. Making it modifiable implies one of the two following options:

1. The complete internal state of rapier needs to be resized to fit the new sizes (because your 100px*100px*100px collider in bevy_rapier will now have a different size in meters in rapier).
2. Or the internal state of bevy_rapier needs to be resized to fit the new pixel sizes (because you 1m*1m*1m collider in rapier new has a different size in pixels in bevy_rapier).

The option (1) would be far too expensive. The option (2) could be considered but will still be quite expensive since it involves modifying all the pixel-sized colliders and as wall as all the transform, velocity, and force-related components affected by a rigid/body or collider.

The last option is for you to deal with the pixels-to-meter conversion: you set 1 pixel = 1 meter (and express your graphics elements in meters), and the you setup a camera to zoom the scene to the visual size that works for you.