shade_global: Function for calculation of global shading on raster data
In JanCaha/rasterShade: Wrapper around rayshader package

This function is just a wrapper around ray_shade that supports directly using Raster in the function. The function also tries to set "reasonable" default values for parameters.

shade_global_date_time(
  surface_raster,
  date = as.character(Sys.Date()),
  time = "noon",
  tzone = "UTC",
  search_distance = 200,
  z_value = 1,
  verbose = FALSE
)

shade_global_sun_position(
  surface_raster,
  sun_elevation = 45,
  sun_azimuth = 180,
  search_distance = 200,
  z_value = 1,
  verbose = FALSE
)

`surface_raster`	Object of class RasterLayer.
`date`	Date specified as `character` in form `YYYY-MM-DD`. Default value is `Sys.Date`.
`time`	Either character representation of time (in format `HH:MM:SS`), or `hms` class, or one of text values: `"noon", "sunrise", "sunset", "goldenHour", "goldenHourEnd"`. The textual representation is used to determine sun elevation using function `getSunlightPosition`. Value `"sunrise"` represents end of sunrise, while `"sunset"` represents start of sunset. Default value is `"noon"`.
`tzone`	a character string that specifies which time zone to parse the date with. The string must be a time zone that is recognized by the user's OS. If no time zone is given the default value `"UTC"` is used. Default value `"UTC"`.
`search_distance`	Distance in which sun blocking objects are searched for, specified in map units. Default value is `200` map units.
`z_value`	numeric value indicating the scale between xy and z. Typical use is if the distance is measured in meters and elevation in foots, in such case the z value needs to be recalculated to meters. Default value is `1`, which means that both measures use the same units.
`verbose`	Should informative message be printed? Default `FALSE`.
`sun_elevation`	Numeric value, from range 0 - 90, with 0 being sun elevation directly on horizon while 90 means that sun is directly above the surface. Default value is `45`.
`sun_azimuth`	Numeric value that specifies azimuth from which the sun is shining on the surface. Value has to be from the range 0 - 360. Default value is `180`.