31 lines
1.1 KiB
JavaScript
31 lines
1.1 KiB
JavaScript
// Reads public/data/buildings.bin (written by scripts/build-buildings.mjs) into the same
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// [height, x0, z0, x1, z1, …] arrays the OSM buildings in mellat.json use.
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export function decodeBuildings(buffer) {
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const view = new DataView(buffer);
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const magic = String.fromCharCode(...new Uint8Array(buffer, 0, 4));
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if (magic !== 'RMB2') throw new Error(`unknown buildings file ${magic}`);
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const count = view.getUint32(4, true),
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minX = view.getFloat32(8, true),
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minZ = view.getFloat32(12, true),
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step = view.getFloat32(16, true);
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const buildings = new Array(count);
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let o = 20;
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for (let b = 0; b < count; b++) {
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const n = view.getUint8(o),
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height = view.getUint8(o + 1) * 0.5;
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o += 2;
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const building = new Array(1 + n * 2);
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building[0] = height;
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let qx = 0,
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qz = 0;
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for (let i = 0; i < n; i++, o += 4) {
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qx = i ? qx + view.getInt16(o, true) : view.getUint16(o, true);
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qz = i ? qz + view.getInt16(o + 2, true) : view.getUint16(o + 2, true);
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building[1 + i * 2] = minX + qx * step;
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building[2 + i * 2] = minZ + qz * step;
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}
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buildings[b] = building;
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}
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return buildings;
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}
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