Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

docs: xr cam details #363

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

docs: xr cam details #363

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 11 additions & 2 deletions docs/getting-started/faq.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,16 @@ useFrame((state) => console.log(state.camera.getWorldPosition(new Vector3())))

## How can I change the camera position in XR?

In contrast to non-immersive 3D applications, the camera transformation in MR/VR/AR applications should never be directly controlled by the developer since the user's head movement must control the camera's transformation. Therefore, pmndrs/xr provides the XROrigin component, which allows to control where the session's origin is placed inside the 3D scene. The session origin is at the users' feet once they recenter their session. This allows to implicitly control the camera position but prevents the user from getting motion sick when their movement is not reflected in the camera's movement.
XR provides its own camera, which becomes the `default` one, once xr-session starts.

In contrast to non-immersive 3D applications, the camera transformation in MR/VR/AR applications should never be directly controlled by the developer since the user's head movement must control the camera's transformation.

Therefore, pmndrs/xr provides the `XROrigin` component, which allows to control where the session's origin is placed inside the 3D scene. The session origin is at the users' feet once they recenter their session. This allows to implicitly control the camera position but prevents the user from getting motion sick when their movement is not reflected in the camera's movement.

> [!IMPORTANT]
> Hence:
> - don't touch the position/rotation of the XR camera
> - don't change its fov (it is handled by the device)

## Having problems accessing the camera position or rotation.

Expand Down Expand Up @@ -73,4 +82,4 @@ WebXR is not supported on iOS Safari yet. The alternative is to use products suc

## XRSpace

If you are placing `<XRSpace>` components outside of the `<XROrigin>` while changing the transformation of the `<XROrigin>` (e.g. by setting `<XROrigin position={[0,1,0]} />`), the elements rendered inside of the `<XRSpace>` will not be transformed with the origin. If the transformations of the origin should be applied to the `<XRSpace>`, make sure to place those components inside the `<XROrigin>`. Not placing `<XRSpace>` components into the `<XROrigin>` can be useful in scenarios where you want to move the `<XROrigin>` independently from the `<XRSpace>`. For instance, building a virtual elevator where your actual room is duplicated into the x-axis so that you can use the elevator to travel between multiple instances of your room.
If you are placing `<XRSpace>` components outside of the `<XROrigin>` while changing the transformation of the `<XROrigin>` (e.g. by setting `<XROrigin position={[0,1,0]} />`), the elements rendered inside of the `<XRSpace>` will not be transformed with the origin. If the transformations of the origin should be applied to the `<XRSpace>`, make sure to place those components inside the `<XROrigin>`. Not placing `<XRSpace>` components into the `<XROrigin>` can be useful in scenarios where you want to move the `<XROrigin>` independently from the `<XRSpace>`. For instance, building a virtual elevator where your actual room is duplicated into the x-axis so that you can use the elevator to travel between multiple instances of your room.