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Add cache for coveringTiles #105

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ghost wants to merge 1 commit into from
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Add cache for coveringTiles #105

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32 changes: 26 additions & 6 deletions src/geo/transform.js
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@ class Transform {
_constraining: boolean;
_posMatrixCache: {[_: string]: Float32Array};
_alignedPosMatrixCache: {[_: string]: Float32Array};
_coveringTilesCache: {[_: string]: Array<any>};

constructor(minZoom: ?number, maxZoom: ?number, minPitch: ?number, maxPitch: ?number, renderWorldCopies: boolean | void) {
this.tileSize = 512; // constant
Expand All @@ -80,6 +81,7 @@ class Transform {
this._edgeInsets = new EdgeInsets();
this._posMatrixCache = {};
this._alignedPosMatrixCache = {};
this._coveringTilesCache = {};
}

clone(): Transform {
Expand Down Expand Up @@ -318,10 +320,19 @@ class Transform {
minzoom?: number,
maxzoom?: number,
roundZoom?: boolean,
reparseOverscaled?: boolean,
renderWorldCopies?: boolean
reparseOverscaled?: boolean
}
): Array<OverscaledTileID> {

const loadCacheEntry = (cacheEntry): Array<OverscaledTileID> => {
return cacheEntry.map(it => new OverscaledTileID(it.overscaledZ, it.wrap, it.zoom, it.x, it.y));
};

const optionsKey = JSON.stringify([options, this._renderWorldCopies]);
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@ghost ghost Mar 17, 2021

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Probably the ugliest part about this patch:

  • Using an array to add this._renderWorldCopies into the hash key, to ensure that changes to that will invalidate the cache.
  • Using JSON.stringify on all arguments to construct a unique hash key.

if (this._coveringTilesCache[optionsKey]) {
return loadCacheEntry(this._coveringTilesCache[optionsKey]);
}

let z = this.coveringZoomLevel(options);
const actualZ = z;

Expand Down Expand Up @@ -356,7 +367,7 @@ class Transform {

// Do a depth-first traversal to find visible tiles and proper levels of detail
const stack = [];
const result = [];
const cacheEntry = [];
const maxZoom = z;
const overscaledZ = options.reparseOverscaled ? actualZ : z;

Expand Down Expand Up @@ -399,8 +410,13 @@ class Transform {

// Have we reached the target depth or is the tile too far away to be any split further?
if (it.zoom === maxZoom || (longestDim > distToSplit && it.zoom >= minZoom)) {
result.push({
tileID: new OverscaledTileID(it.zoom === maxZoom ? overscaledZ : it.zoom, it.wrap, it.zoom, x, y),
cacheEntry.push({
tileParameters: {
overscaledZ: it.zoom === maxZoom ? overscaledZ : it.zoom,
wrap: it.wrap,
zoom: it.zoom,
x, y
},
distanceSq: vec2.sqrLen([centerPoint[0] - 0.5 - x, centerPoint[1] - 0.5 - y])
});
continue;
Expand All @@ -414,7 +430,10 @@ class Transform {
}
}

return result.sort((a, b) => a.distanceSq - b.distanceSq).map(a => a.tileID);
const sortedCacheEntry = cacheEntry.sort((a, b) => a.distanceSq - b.distanceSq).map(a => a.tileParameters);
this._coveringTilesCache[optionsKey] = sortedCacheEntry;

return loadCacheEntry(sortedCacheEntry);
}

resize(width: number, height: number) {
Expand Down Expand Up @@ -765,6 +784,7 @@ class Transform {

this._posMatrixCache = {};
this._alignedPosMatrixCache = {};
this._coveringTilesCache = {};
}

maxPitchScaleFactor() {
Expand Down