@loaders.gl/3d-tiles
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3D Tiles, an open standard for streaming massive heterogeneous 3D geospatial datasets.
42 lines (41 loc) • 1.84 kB
JavaScript
// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright vis.gl contributors
import { Vector3 } from '@math.gl/core';
import { GL } from '@loaders.gl/math';
// Prepare attribute for positions
export function normalize3DTilePositionAttribute(tile, positions, options) {
if (!tile.isQuantized) {
return positions;
}
// For quantized posititions, either expand to Float32Array or return custom accessor
// https://github.com/AnalyticalGraphicsInc/3d-tiles/blob/master/specification/TileFormats/Instanced3DModel/README.md#quantized-positions
// Optionally decodes quantized positions on GPU, for simpler renderers that don't accept normalized attributes
if (options['3d-tiles'] && options['3d-tiles'].decodeQuantizedPositions) {
tile.isQuantized = false;
return decodeQuantizedPositions(tile, positions);
}
// Default: Use normalized shorts directly, no copying/processing.
// NOTE: The "missing" offset/scaling operations are automatically added to modelMatrix if `tile.isQuantized === true`
return {
type: GL.UNSIGNED_SHORT,
value: positions,
size: 3,
normalized: true
};
}
// Pre-scale quantized positions on CPU
function decodeQuantizedPositions(tile, positions) {
const scratchPosition = new Vector3();
const decodedArray = new Float32Array(tile.pointCount * 3);
for (let i = 0; i < tile.pointCount; i++) {
// POSITION = POSITION_QUANTIZED / 65535.0 * QUANTIZED_VOLUME_SCALE + QUANTIZED_VOLUME_OFFSET
scratchPosition
.set(positions[i * 3], positions[i * 3 + 1], positions[i * 3 + 2])
.scale(1 / tile.quantizedRange)
.multiply(tile.quantizedVolumeScale)
.add(tile.quantizedVolumeOffset)
.toArray(decodedArray, i * 3);
}
return decodedArray;
}