Low-level wk filters and handlers

```
# S3 method for s2_geography
wk_handle(
handleable,
handler,
...,
s2_projection = s2_projection_plate_carree(),
s2_tessellate_tol = Inf
)
s2_geography_writer(
oriented = FALSE,
check = TRUE,
projection = s2_projection_plate_carree(),
tessellate_tol = Inf
)
# S3 method for s2_geography
wk_writer(handleable, ...)
s2_trans_point()
s2_trans_lnglat()
s2_projection_plate_carree(x_scale = 180)
s2_projection_mercator(x_scale = 20037508.3427892)
s2_hemisphere(centre)
s2_world_plate_carree(epsilon_east_west = 0, epsilon_north_south = 0)
s2_projection_orthographic(centre = s2_lnglat(0, 0))
```

- handleable
A geometry vector (e.g.,

`wkb()`

,`wkt()`

,`xy()`

,`rct()`

, or`sf::st_sfc()`

) for which`wk_handle()`

is defined.- handler
A wk_handler object.

- ...
Passed to the

`wk_handle()`

method.- oriented
TRUE if polygon ring directions are known to be correct (i.e., exterior rings are defined counter clockwise and interior rings are defined clockwise).

- check
Use

`check = FALSE`

to skip error on invalid geometries- projection, s2_projection
One of

`s2_projection_plate_carree()`

or`s2_projection_mercator()`

- tessellate_tol, s2_tessellate_tol
An angle in radians. Points will not be added if a line segment is within this distance of a point.

- x_scale
The maximum x value of the projection

- centre
The center point of the orthographic projection

- epsilon_east_west, epsilon_north_south
Use a positive number to define the edges of a Cartesian world slightly inward from -180, -90, 180, 90. This may be used to define a world outline for a projection where projecting at the extreme edges of the earth results in a non-finite value.

`s2_projection_plate_carree()`

,`s2_projection_mercator()`

: An external pointer to an S2 projection.