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radar processed in web worker

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Matt Walsh
2025-05-24 16:36:41 -05:00
parent 5567fe37a6
commit 8d20f7672c
2 changed files with 134 additions and 87 deletions
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80
server/scripts/modules/radar-worker.mjs Normal file
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import * as utils from './radar-utils.mjs';
const fetchAsBlob = async (url) => {
const response = await fetch(url);
return response.blob();
};
onmessage = async (e) => {
const baseMapImage = createImageBitmap(await fetchAsBlob('/images/maps/radar.webp'));
const {
url, index, RADAR_HOST, OVERRIDES, radarSourceXY, sourceXY, offsetX, offsetY,
} = e.data;
// calculate offsets and sizes
const width = 2550;
const height = 1600;
const radarOffsetX = 120;
const radarOffsetY = 70;
const radarSourceX = Math.round(radarSourceXY.x / 2);
const radarSourceY = Math.round(radarSourceXY.y / 2);
// create destination context
const baseCanvas = new OffscreenCanvas(640, 367);
const baseContext = baseCanvas.getContext('2d', { alpha: false });
baseContext.imageSmoothingEnabled = false;
// create working context for manipulation
const radarCanvas = new OffscreenCanvas(width, height);
const radarContext = radarCanvas.getContext('2d', { alpha: false });
radarContext.imageSmoothingEnabled = false;
// get the image
const modifiedUrl = OVERRIDES.RADAR_HOST ? url.replace(RADAR_HOST, OVERRIDES.RADAR_HOST) : url;
console.time(`Radar-${index}-fetch`);
const response = await fetch(modifiedUrl);
console.timeEnd(`Radar-${index}-fetch`);
// test response
if (!response.ok) throw new Error(`Unable to fetch radar error ${response.status} ${response.statusText} from ${response.url}`);
// get the blob
console.time(`Radar-${index}-blob`);
const radarImgBlob = await response.blob();
console.timeEnd(`Radar-${index}-blob`);
// assign to an html image element
console.time(`Radar-${index}-loadimg-element`);
const radarImgElement = await createImageBitmap(radarImgBlob);
console.timeEnd(`Radar-${index}-loadimg-element`);
// draw the entire image
radarContext.clearRect(0, 0, width, 1600);
console.time(`Radar-${index}-drawimage`);
radarContext.drawImage(radarImgElement, 0, 0, width, 1600);
console.timeEnd(`Radar-${index}-drawimage`);
// get the base map
console.time(`Radar-${index}-drawbasemap`);
baseContext.drawImage(await baseMapImage, sourceXY.x, sourceXY.y, offsetX * 2, offsetY * 2, 0, 0, 640, 367);
console.timeEnd(`Radar-${index}-drawbasemap`);
// crop the radar image
const cropCanvas = new OffscreenCanvas(640, 367);
const cropContext = cropCanvas.getContext('2d', { willReadFrequently: true });
cropContext.imageSmoothingEnabled = false;
console.time(`Radar-${index}-copy-radar`);
cropContext.drawImage(radarCanvas, radarSourceX, radarSourceY, (radarOffsetX * 2), Math.round(radarOffsetY * 2.33), 0, 0, 640, 367);
console.timeEnd(`Radar-${index}-copy-radar`);
// clean the image
console.time(`Radar-${index}-clean-image`);
utils.removeDopplerRadarImageNoise(cropContext);
console.timeEnd(`Radar-${index}-clean-image`);
// merge the radar and map
console.time(`Radar-${index}-merge`);
utils.mergeDopplerRadarImage(baseContext, cropContext);
console.timeEnd(`Radar-${index}-merge`);
const processedRadar = baseCanvas.transferToImageBitmap();
postMessage(processedRadar, [processedRadar]);
};