The frame the orbit is measured in, about up: the planetarium's own axes,
with the local up standing in for the world's +Y.
east is the world's +Y turned about the up direction, which is the one
reference the scene carries everywhere; where up is +Y — deep space, or
a body's pole — any perpendicular is as good as any other and +X stands in.
The frame is a function of up alone, so a camera that has stopped moving
stays still while the ship underneath it does anything at all.
The third axis is east × up, which on a body is south, and the name is
kept honest rather than flipped: the azimuth swings from east toward it
because that is the sense the planetarium's swings in — observerOffset
runs from +X toward +Z about +Y, and +X × +Y is +Z. A drag's sign is a
fact about the gesture, settled once in applyDrag, so the two cameras
have to turn the same way under the same hand; the geographic basis
(east, north, up) is right-handed the other way about the pole, and an
orbit measured in it moves the hull's near side against the pointer
while the planetarium moves a globe's with it.
- upVec3
- Undocumented