import geomask from "geomask";

// calculate the horizontal segments of pixels
// that fall within the masking geometry
const { rows } = geomask.inside({
  // bounding box in projection of the raster
  // in this case, Web Mercator
  raster_bbox: [
    7698736.857788673, // xmin
    163239.83797837654, // ymin
    10066450.245949663, // xmax
    1325082.6679127468 // ymax
  ],

  // spatial reference system of the raster
  // 3857 is the EPSG code for Web Mercator
  raster_srs: 3857,

  // height of the raster
  raster_height: 475,

  // width of the raster
  raster_width: 968,

  // optional height of pixel in srs units
  pixel_height: 2445.98490512499,

  // optional width of pixel in srs units
  pixel_width: 2445.9849051249894,

  // a masking geometry in GeoJSON format
  // currently, only Polygon and MultiPolygon geometries are supported
  // in the example below, we see a GeoJSON Feature Collection of Polygon Features
  mask: { type: "FeatureCollection", features: [...] },

  // the standard projection used by GeoJSON
  mask_srs: 4326
});

[
  <92 empty items>, // the top 92 rows of the raster don't intersect the geometry mask
  [ [ 500, 500 ] ], // only 1 pixel in this row falls within the geometry mask
  [ [ 499, 501 ] ], // 3 pixels in this row fall within the mask, pixels with index 499, 500 and 501
  [ [ 499, 502 ] ], // 4 pixels from index 499 to 502 fall within the mask
  ... 380 more items
]

import geomask from "geomask";

const { rows } = geomask.outside({ raster_bbox, raster_srs, raster_height, raster_width, mask, mask_srs: 4326 })

[
  [ [0, 967] ], // the top rows of the raster don't intersect the geometry mask
  [ [0, 967] ], // so the outside range extends the whole width of the raster
  [ [0, 967] ],
  <90 rows of [ [0, 967] ]>
  [ [ 0, 499 ], [501, 967] ], // all but one pixel (index 500) falls outside the mask
  ... 382 more items
]

import geomask from "geomask/lite";
import proj4 from "proj4";

geomask.inside({
  raster_bbox: [7698736.857788673, 163239.83797837654, 10066450.245949663, 1325082.6679127468 ],
  raster_height: 475,
  raster_width: 968,
  mask: { type: "FeatureCollection", features: [...] },

  // if your mask is in a different projection than your raster
  // provide a reproject function that converts an [x, y] point
  // from the geometry mask to a point in the raster projection
  reproject: proj4("EPSG:4326", "EPSG:3857").forward
})