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optimize zoom bounds (#38)

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Minor optimization - no point to compute bounds on every calculation - enough to keep them around with const pre-generation.

Co-authored-by: Max Ammann <max@maxammann.org>
This commit is contained in:
Yuri Astrakhan 2022-05-01 12:23:38 -04:00 committed by GitHub
parent 2e5a085748
commit 4f2a5da25a
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 22 additions and 5 deletions
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27
maplibre/src/coords.rs
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@ -17,12 +17,26 @@ pub const EXTENT: f64 = EXTENT_UINT as f64;
pub const TILE_SIZE: f64 = 512.0;
pub const MAX_ZOOM: usize = 32;
// FIXME: MAX_ZOOM is 32, which means max bound is 2^32, which wouldn't fit in u32 or i32
// Bounds are generated 0..=31
pub const ZOOM_BOUNDS: [u32; MAX_ZOOM] = create_zoom_bounds::<MAX_ZOOM>();
const fn create_zoom_bounds<const DIM: usize>() -> [u32; DIM] {
let mut result: [u32; DIM] = [0; DIM];
let mut i = 0;
while i < DIM {
result[i as usize] = 2u32.pow(i as u32);
i += 1;
}
result
}
#[derive(Ord, PartialOrd, Eq, PartialEq, Clone, Copy)]
pub struct Quadkey([u8; MAX_ZOOM]);
impl Quadkey {
pub fn new(quad_encoded: &[u8]) -> Self {
let mut key = [0u8; 32];
let mut key = [0u8; MAX_ZOOM];
key[0] = quad_encoded.len() as u8;
for (i, part) in quad_encoded.iter().enumerate() {
key[i + 1] = *part;
@ -139,7 +153,9 @@ impl TileCoords {
/// The [`TileCoords`] `T(x=5,y=5,z=0)` exceeds its bounds because there is no tile
/// `x=5,y=5` at zoom level `z=0`.
pub fn into_world_tile(self, scheme: TileAddressingScheme) -> Option<WorldTileCoords> {
let bounds = 2i32.pow(self.z as u32);
// FIXME: MAX_ZOOM is 32, which means max bound is 2^32, which wouldn't fit in u32 or i32
// Note that unlike WorldTileCoords, values are signed (no idea why)
let bounds = ZOOM_BOUNDS[self.z as usize] as i32;
let x = self.x as i32;
let y = self.y as i32;
@ -191,7 +207,8 @@ impl WorldTileCoords {
/// The [`WorldTileCoords`] `WT(x=5,y=5,z=0)` exceeds its bounds because there is no tile
/// `x=5,y=5` at zoom level `z=0`.
pub fn into_tile(self, scheme: TileAddressingScheme) -> Option<TileCoords> {
let bounds = 2u32.pow(self.z as u32);
// FIXME: MAX_ZOOM is 32, which means max bound is 2^32, which wouldn't fit in u32 or i32
let bounds = ZOOM_BOUNDS[self.z as usize];
let x = self.x as u32;
let y = self.y as u32;
@ -244,7 +261,7 @@ impl WorldTileCoords {
/// Adopted from [tilebelt](https://github.com/mapbox/tilebelt)
pub fn build_quad_key(&self) -> Option<Quadkey> {
let bounds = 2u32.pow(self.z as u32);
let bounds = ZOOM_BOUNDS[self.z as usize];
let x = self.x as u32;
let y = self.y as u32;
@ -252,7 +269,7 @@ impl WorldTileCoords {
return None;
}
let mut key = [0u8; 32];
let mut key = [0u8; MAX_ZOOM];
key[0] = self.z;