# (C) Copyright 2005- ECMWF.

# TEMPLATE 3.10, Mercator
include "grib2/template.3.shape_of_the_earth.def"

constant isGridded = true;

unsigned[4] Ni : dump;
alias numberOfPointsAlongAParallel = Ni;
alias Nx = Ni;
alias numberOfPointsAlongXAxis = Ni;
alias geography.Ni=Ni;

unsigned[4] Nj : dump;
alias numberOfPointsAlongAMeridian = Nj;
alias Ny = Nj;
alias numberOfPointsAlongYAxis = Nj;
alias geography.Nj=Nj;

# La1 - latitude of first grid point
signed[4] latitudeOfFirstGridPoint: edition_specific,no_copy ;
alias La1 =  latitudeOfFirstGridPoint;
meta geography.latitudeOfFirstGridPointInDegrees scale(latitudeOfFirstGridPoint,oneConstant,grib2divider,truncateDegrees) : dump;

# Lo1 - longitude of first grid point
signed[4] longitudeOfFirstGridPoint : edition_specific,no_copy;
alias Lo1 =  longitudeOfFirstGridPoint;
meta geography.longitudeOfFirstGridPointInDegrees scale(longitudeOfFirstGridPoint,oneConstant,grib2divider,truncateDegrees) : dump;

include "grib2/template.3.resolution_flags.def"

# LaD - Latitude(s) at which the Mercator projection intersects the Earth
# (Latitude(s) where Di and Dj are specified)
signed[4] LaD : edition_specific,no_copy;
meta geography.LaDInDegrees scale(LaD,oneConstant,grib2divider,truncateDegrees) : dump;

# La2 - latitude of last grid point
signed[4] latitudeOfLastGridPoint : edition_specific,no_copy;
alias La2 =  latitudeOfLastGridPoint;
meta geography.latitudeOfLastGridPointInDegrees scale(latitudeOfLastGridPoint,oneConstant,grib2divider,truncateDegrees) : dump;

# Lo2 - longitude of last grid point
signed[4] longitudeOfLastGridPoint: edition_specific,no_copy ;
alias Lo2 =  longitudeOfLastGridPoint;
meta geography.longitudeOfLastGridPointInDegrees scale(longitudeOfLastGridPoint,oneConstant,grib2divider,truncateDegrees) : dump;

include "grib2/template.3.scanning_mode.def"

# Orientation of the grid, angle between i direction on the map and the equator
# NOTE 1: Limited to the range of 0 to 90 degrees; if the angle of orientation of the grid is neither 0 nor 90 degrees,
#         Di and Dj must be equal to each other
unsigned[4] orientationOfTheGrid : dump ;
meta geography.orientationOfTheGridInDegrees
    scale(orientationOfTheGrid,oneConstant,grib2divider,truncateDegrees) : dump;

# Di - longitudinal direction grid length
# NOTE 2: Grid lengths are in units of 10**-3 m, at the latitude specified by LaD
unsigned[4] Di : edition_specific,no_copy;
alias longitudinalDirectionGridLength = Di;
meta geography.DiInMetres scale(Di,oneConstant,thousand,truncateDegrees) : dump;
alias DxInMetres = DiInMetres;

# Dj - latitudinal direction grid length
# NOTE 2: Grid lengths are in units of 10**-3 m, at the latitude specified by LaD
unsigned[4] Dj : edition_specific,no_copy ;
alias latitudinalDirectionGridLength = Dj;
meta geography.DjInMetres scale(Dj,oneConstant,thousand,truncateDegrees) : dump;
alias DyInMetres = DjInMetres;

iterator mercator(numberOfPoints,missingValue,values,
          radius,Ni,Nj,
          latitudeOfFirstGridPointInDegrees, longitudeOfFirstGridPointInDegrees,
          LaDInDegrees,
          latitudeOfLastGridPointInDegrees, longitudeOfLastGridPointInDegrees,
          orientationOfTheGridInDegrees,
          DiInMetres,DjInMetres,
          iScansNegatively, jScansPositively,
          jPointsAreConsecutive, alternativeRowScanning);

nearest mercator(values,radius,Nx,Ny);

meta latLonValues latlonvalues(values);
alias latitudeLongitudeValues=latLonValues;
meta latitudes latitudes(values,0);
meta longitudes longitudes(values,0);
meta distinctLatitudes latitudes(values,1);
meta distinctLongitudes longitudes(values,1);