Struct MercatorDem 

pub struct MercatorDem { /* private fields */ }

A contiguous rectangular block of decoded web-mercator (XYZ) DEM tiles, stitched into a single elevation grid and sampleable by longitude / latitude.

The stitched grid is row-major north → south, tiles_x * tile_size columns by tiles_y * tile_size rows. Sampling outside the block clamps to the nearest edge sample, so a halo that slightly overshoots the fetched coverage degrades gracefully rather than panicking — but for correct results the block should cover the target bounds (plus any halo).

Implementations

impl MercatorDem

pub fn new( zoom: u8, x0: u32, y0: u32, tiles_x: u32, tiles_y: u32, tile_size: u32, elev: Vec<f32>, ) -> Self

Wrap an already-stitched elevation block.

elev must be row-major north → south with (tiles_x*tile_size) * (tiles_y*tile_size) entries.

Panics

Panics on a length mismatch, or if any tile dimension is zero.

pub fn from_tiles<F>( zoom: u8, x0: u32, y0: u32, tiles_x: u32, tiles_y: u32, tile_size: u32, get_tile: F, ) -> Self

where F: FnMut(u8, u32, u32) -> Vec<f32>,

Build a block by pulling each XYZ tile through get_tile, which returns that tile’s decoded elevations (tile_size², row-major north → south). The closure is where you do your fetch + heightmap decode; for async callers, pre-fetch into a map and look it up here.

Tiles are requested in row-major order (x0, y0) … (x0+tiles_x-1, y0+tiles_y-1).

Panics

Panics if any returned tile does not have exactly tile_size² samples.

pub fn tiles_covering( zoom: u8, west: f64, south: f64, east: f64, north: f64, ) -> (u32, u32, u32, u32)

Range of XYZ tiles at zoom covering a longitude/latitude box, returning (x0, y0, tiles_x, tiles_y).

Widen the box by your halo before calling if you intend to sample a buffer beyond the tile (e.g. for buffered_geodetic).

pub fn width_px(&self) -> u32

Stitched-grid width in pixels (tiles_x * tile_size).

pub fn height_px(&self) -> u32

Stitched-grid height in pixels (tiles_y * tile_size).

pub fn sample(&self, lon: f64, lat: f64) -> f32

Bilinearly sample the elevation at (lon, lat) in degrees.

Latitude is clamped to the web-mercator limit. Positions outside the fetched block clamp to the nearest edge sample. NaN samples (e.g. missing data filled by the caller) are tolerated: the interpolation falls back to any defined neighbour, returning NaN only if all four corners are NaN.

pub fn geodetic_grid(&self, bounds: &TileBounds, grid_size: u32) -> Vec<f32>

Resample onto a geodetic grid_size × grid_size grid covering bounds, row-major north → south — ready for crate::terrain::encode_terrain.

Panics

Panics if grid_size < 2.

pub fn buffered_geodetic( &self, bounds: &TileBounds, tile_grid_size: u32, buffer: u32, ) -> BufferedElevations

Resample onto a halo-extended geodetic grid — a BufferedElevations for crate::terrain::NormalMode::BufferedGradient.

The inner tile_grid_size × tile_grid_size block matches geodetic_grid; the surrounding buffer-cell strip is sampled from the neighbour area (so make sure this MercatorDem was built to cover bounds widened by the halo).

Panics

Panics if tile_grid_size < 2.

Trait Implementations

impl Clone for MercatorDem

fn clone(&self) -> MercatorDem

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MercatorDem

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.