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Add some math verifying relationship between get_viewer_pose and get_pose

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Manish Goregaokar 2019-04-05 18:42:57 -07:00
parent 91378cc859
commit ea3609b42e
2 changed files with 28 additions and 6 deletions
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10
components/script/dom/xrreferencespace.rs
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@ -56,12 +56,18 @@ impl XRReferenceSpaceMethods for XRReferenceSpace {
impl XRReferenceSpace {
/// Gets pose of the viewer with respect to this space
///
/// This is equivalent to `get_pose(self).inverse() * get_pose(viewerSpace)`, however
/// we specialize it to be efficient
/// This is equivalent to `get_pose(self).inverse() * get_pose(viewerSpace)` (in column vector notation),
/// however we specialize it to be efficient
pub fn get_viewer_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
let pose = self.get_unoffset_viewer_pose(base_pose);
// This may change, see https://github.com/immersive-web/webxr/issues/567
// in column-vector notation,
// get_viewer_pose(space) = get_pose(space).inverse() * get_pose(viewer_space)
// = (get_unoffset_pose(space) * offset).inverse() * get_pose(viewer_space)
// = offset.inverse() * get_unoffset_pose(space).inverse() * get_pose(viewer_space)
// = offset.inverse() * get_unoffset_viewer_pose(space)
let offset = self.transform.get().transform();
let inverse = offset.inverse();
inverse.pre_mul(&pose)

24
components/script/dom/xrstationaryreferencespace.rs
View file

@ -56,25 +56,41 @@ impl XRStationaryReferenceSpace {
/// Does not apply originOffset, use get_viewer_pose on XRReferenceSpace instead
pub fn get_unoffset_viewer_pose(&self, viewer_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
let viewer_pose = XRSpace::viewer_pose_from_frame_data(viewer_pose);
// all math is in column-vector notation
// we use the following equation to verify correctness here:
// get_viewer_pose(space) = get_pose(space).inverse() * get_pose(viewer_space)
match self.ty {
XRStationaryReferenceSpaceSubtype::Eye_level => {
// get_viewer_pose(eye_level) = get_pose(eye_level).inverse() * get_pose(viewer_space)
// = I * viewer_pose
// = viewer_pose
// we get viewer poses in eye-level space by default
viewer_pose
}
},
XRStationaryReferenceSpaceSubtype::Floor_level => {
// XXXManishearth support getting floor info from stage parameters
// get_viewer_pose(floor_level) = get_pose(floor_level).inverse() * get_pose(viewer_space)
// = Translate(-2).inverse() * viewer_pose
// = Translate(2) * viewer_pose
// assume approximate user height of 2 meters
let floor_to_eye: RigidTransform3D<f64> = Vector3D::new(0., 2., 0.).into();
floor_to_eye.pre_mul(&viewer_pose)
}
},
XRStationaryReferenceSpaceSubtype::Position_disabled => {
// get_viewer_pose(pos_disabled) = get_pose(pos_disabled).inverse() * get_pose(viewer_space)
// = viewer_pose.translation.inverse() * viewer_pose
// = viewer_pose.translation.inverse() * viewer_pose.translation
// * viewer_pose.rotation
// = viewer_pose.rotation
// This space follows the user around, but does not mirror the user's orientation
// Thus, the viewer's pose relative to this space is simply their orientation
viewer_pose.rotation.into()
}
},
}
}
/// Gets pose represented by this space