VR Scene with Z axis up

Questions
1

I have a scene with the Z axis up and the XY axes along the ground plane. To do this I use this trick:

camera.rotation.order = "ZXY"
camera.rotation.x = Math.PI * 0.5
camera.rotation.y = Math.PI * 0.5
camera.rotation.z = Math.PI
camera.up.set(0.0, 0.0, 1.0)

camHolder = new THREE.Object3D()
camHolder.rotation.order = "ZYX"
camHolder.add(this.camera)

scene.add(camHolder)

Then I move/rotate camHolder around the scene.

However when I enable VR using the Vive, my scene is sideways. Is there any workaround for this or must I use the Y axis as up in my scene?

1 Like
2

I’m not sure if there’s a way of doing this for VR, but it’s generally strongly recommended to keep y as the up axis.

Is there a reason that you need to change this?

3

Mainly because I have existing projects I wanted to add VR support to.

4

The standard for WebVR is as follows (see reference):

  • positive X is to the user’s right
  • positive Y is up
  • positive Z is behind the user

This setup is immutable and you should not perform any weird manual conversion. I suggest to use Y-UP in your scenes.

3 Likes
5

All right, I guess that decides it. Thanks.

6

Well, I have the exact same Problem. I am bound to use a right handed coordinate system with a XY ground plane, as positions get synced to a 2d map and rely on geopositions.

but there are workarounds for that:

  1. you rotate your camera 90° around x before everything else:
    this.xOffset = new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(1,0,0), THREE.Math.degToRad(90));
    this.deviceOrientation = new THREE.Quaternion();
    this.deviceOrientation.fromArray( pose.orientation );
    this.objectQuat = new THREE.Quaternion();
    this.objectQuat.multiplyQuaternions(this.xOffset,this.deviceOrientation);

  2. you transform every pose you get by the following conversion:

    var adjustedPos = new THREE.Vector3(
    pose.position[0],
    pose.position[2] * (-1),
    pose.position[1]
    );

7

being immutable doesnt necessarily mean it is hard to workaround. you just have to adjust the sensor data/pose. Although this might get messy when using the standingMatrix.