Fixed setPose

[Sparib]

The first point is just something that my team and our sister-team overlooked, the second point it the good stuff.

The Origins

I have been working with ftc265 for a while and encountered numerous errors and weird things when it came to using the setPose function. I believe I have found the problems, sources of the error, and the fixes for them.

1) setPose is weird.

The reason that sometimes setPose doesn't work if you do it too quickly after initialization is as follows:

The camera begins initialization at new T265Camera().\ Then, setPose is ran, but initialization isn't complete, so setPose defaults to using new Pose2d() as the "origin" for translation.\ Then, the camera fully initializes and whatever the position it started at is used, with the incorrect offset from setPose.

Example:

(Where there is something that looks like (0,0), it means (x,y). I ignore rotation for simplicity's sake, but it acts the same)\ Initialization begins\ setPose(0,0) is ran\ Camera gives a reference of (0,0) because it has yet to initialize fully\ The offset is none because the origin and new pose for setPose were the same\ The camera fully initializes at a position of (10,2) and that is passed to the program because there is no offset.

The Fix:

Wait until getLastReceivedUpdate() returns actual numbers and not just (0,0), that way setPose has actual values to calculate off.

2) setPose is broken.

I have no idea how no one has noticed this and asked about it or even explored it for themselves, as I did, but I have found that the setPose function is truly broken.

The reason that setPose() does weird things when you try to use it multiple times is because it uses the translated position in the offset calculation instead of the camera's position

That makes no sense so,

Explanation:

There are 4 values in this example

Camera Pos = The position that the actual hardware camera believes it's at (not affected by offset)
Offset Pos = The position that is added to the camera pos to get the translated pos
Trans Pos = The position after (Camera Pos) + (Offset Pos), this is given to the user
New Pos = The position for calculating the offset pos (used as setPose(New Pos))

Also, something like (x1,y1) - (x2,y2) is the same as (x1-x2, y1-y2). The same goes when using names instead of numbers.

The way the camera currently works is that Offset Pos is calculated by doing (New Pos) - (Trans Pos).\ This poses problems.

Given:

Camera Pos = (10,2)
Offset Pos = (0,0)
(10,2) + (0,0):
Trans Pos = (10,2)

If we then set New Pos to be (0,0), then the values change to be:

Camera Pos = (10,2)
Offset Pos = (-10,-2)
(10,2) + (-10,-2):
Trans Pos = (0,0)

This is normal!

However, if you then set New Pos to be (0,0) again, then the calculation is done with the translated pos causing the offset to go back to (0,0) because (New Pos) - (Trans Pos) = (0,0), which gives this:

Camera Pos = (10,2)
Offset Pos = (0,0)
(10,2) + (0,0):
Trans Pos = (10,2)

Therefore, setPose is broken in the library.

The fix:

If the camera instead calculates Offset Pos by doing (New Pos) - (Camera Pos), we get what we want, always making (Trans Pos) = (New Pos) when New Pos is changed.

These example take place in a world where the camera stays perfectly still. If you introduce movement, the calculations get even more broken.

Example for fun :P

Camera Pos = (6,7)
Offset Pos = (0,0)
(6,7) + (0,0):
Trans Pos = (6,7)

Run setPose(0,0) and you get:

Camera Pos = (6,7)
Offset Pos = (-6,-7)
(6,7) + (-6,-7):
Trans Pos = (0,0)

Then, move the camera by (+2, -1) and the values become:

Camera Pos = (8,6)
Offset Pos = (-6,-7)
(8,6) + (-6,-7)
Trans Pos = (2,-1)

Try doing setPose(0,0) again, and offset is calculated (New Pos) - (Trans Pos) = (Offset Pos), or (0,0) - (2,-1) = (-2,1), making the values after setPose:

Camera Pos = (8,6)
Offset Pos = (-2,1)
(8,6) + (-2,1):
Trans Pos = (6,7)

With Trans Pos not being (0,0) this concludes that setPose is fundamentally broken.

My edits:

I added a variable called mLastRecievedCameraUpdate (spelled incorrectly to match the incorrect spelling of mLastRecievedCameraUpdate) here. I also added a consumer for that variable called cameraConsumer here. \ I then created a new function called consumeCameraUpdate which takes the same parameters as consumePoseUpdate here, and that is called by the C++ file (here). \ After being called it passes all of its arguments to consumeCameraUpdate, which I will probably soon change to it passing the pose instead of x, y, and radians.\ The final modification was making setPose use mLastRecievedCameraUpdate instead of mLastRecievedUpdate (here). mLastRecievedCameraUpdate is not meant to be sent to the end user, thus the absence of any getter function.