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Merge branch 'master' into chore/buildDockerfile

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This commit is contained in:
Kohl Listi 2021-08-03 19:46:13 +02:00
commit 4506806b73
1 changed files with 38 additions and 15 deletions
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53
src/serve_rendered.js
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@ -27,6 +27,8 @@ const utils = require('./utils');
const FLOAT_PATTERN = '[+-]?(?:\\d+|\\d+\.?\\d+)';
const httpTester = /^(http(s)?:)?\/\//;
const RADIUS_EARTH_EQUATORIAL_IN_M = 6378137;
const getScale = scale => (scale || '@1x').slice(1, 2) | 0;
mbgl.on('message', e => {
@ -173,25 +175,46 @@ const renderOverlay = (z, x, y, bearing, pitch, w, h, scale,
return canvas.toBuffer();
};
const toRadian = (deg) => deg*Math.PI/180;
const getDistanceForPoints = (a, b) => {
// calculates great-circle distance between two points on a sphere in
// meters (see https://en.wikipedia.org/wiki/Haversine_formula)
const phi = [toRadian(a[1]), toRadian(b[1])]; // latitudes
const lambda = [toRadian(a[0]), toRadian(b[0])]; // longitudes
const h = (Math.sin((phi[1]-phi[0])/2))**2 +
Math.cos(phi[0]) * Math.cos(phi[1]) *
(Math.sin((lambda[1]-lambda[0])/2))**2;
return 2 * RADIUS_EARTH_EQUATORIAL_IN_M * Math.asin(Math.sqrt(h));
};
const calcZForBBox = (bbox, w, h, query) => {
let z = 25;
// Use equation for horizontal distance per tile given zoom and latitude
// see https://wiki.openstreetmap.org/wiki/Zoom_levels#Distance_per_pixel_math
//
// S_pixel * T = S_tile = C * cos(l) / (2^z) =
// S_tile := horizontal distance per tile
// S_pixel := horizontal distance per pixel
// T := tile size
// C := Equatorial circumference of Earth
// l := centered latitude of bbox
// z := zoom level
//
// => z = log2( C * cos(l) / (S_pixel*T) )
const padding = query.padding !== undefined ?
parseFloat(query.padding) : 0.1;
// points (use centered latitude of bbox)
const latCenter = bbox[1]+(bbox[3]-bbox[1])/2;
const east = [bbox[0], latCenter];
const west = [bbox[2], latCenter];
const minCorner = mercator.px([bbox[0], bbox[3]], z),
maxCorner = mercator.px([bbox[2], bbox[1]], z);
const w_ = w / (1 + 2 * padding);
const h_ = h / (1 + 2 * padding);
// calculate zoom
const distancePerPixel = getDistanceForPoints(east, west) / w;
const distancePerTile = distancePerPixel * 256;
const circumferenceEarth = 2 * Math.PI * RADIUS_EARTH_EQUATORIAL_IN_M;
const z = Math.log2(Math.abs(circumferenceEarth * Math.cos(toRadian(latCenter)) / distancePerTile));
z -= Math.max(
Math.log((maxCorner[0] - minCorner[0]) / w_),
Math.log((maxCorner[1] - minCorner[1]) / h_)
) / Math.LN2;
z = Math.max(Math.log(Math.max(w, h) / 256) / Math.LN2, Math.min(25, z));
return z;
// bounds enforcement [0,25]
return Math.min(Math.abs(z), 25)
};
const existingFonts = {};