three
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JavaScript 3D library
310 lines (198 loc) • 8.36 kB
JavaScript
import { Color, ColorManagement, SRGBColorSpace } from 'three';
/* global DracoEncoderModule */
/**
* An exporter to compress geometry with the Draco library.
*
* [Draco]{@link https://google.github.io/draco/} is an open source library for compressing and
* decompressing 3D meshes and point clouds. Compressed geometry can be significantly smaller,
* at the cost of additional decoding time on the client device.
*
* Standalone Draco files have a `.drc` extension, and contain vertex positions,
* normals, colors, and other attributes. Draco files *do not* contain materials,
* textures, animation, or node hierarchies – to use these features, embed Draco geometry
* inside of a glTF file. A normal glTF file can be converted to a Draco-compressed glTF file
* using [glTF-Pipeline]{@link https://github.com/AnalyticalGraphicsInc/gltf-pipeline}.
*
* ```js
* const exporter = new DRACOExporter();
* const data = exporter.parse( mesh, options );
* ```
*/
class DRACOExporter {
/**
* Parses the given mesh or point cloud and generates the Draco output.
*
* @param {(Mesh|Points)} object - The mesh or point cloud to export.
* @param {DRACOExporter~Options} options - The export options.
* @return {ArrayBuffer} The exported Draco.
*/
parse( object, options = {} ) {
options = Object.assign( {
decodeSpeed: 5,
encodeSpeed: 5,
encoderMethod: DRACOExporter.MESH_EDGEBREAKER_ENCODING,
quantization: [ 16, 8, 8, 8, 8 ],
exportUvs: true,
exportNormals: true,
exportColor: false,
}, options );
if ( DracoEncoderModule === undefined ) {
throw new Error( 'THREE.DRACOExporter: required the draco_encoder to work.' );
}
const geometry = object.geometry;
const dracoEncoder = DracoEncoderModule();
const encoder = new dracoEncoder.Encoder();
let builder;
let dracoObject;
if ( object.isMesh === true ) {
builder = new dracoEncoder.MeshBuilder();
dracoObject = new dracoEncoder.Mesh();
const vertices = geometry.getAttribute( 'position' );
builder.AddFloatAttributeToMesh( dracoObject, dracoEncoder.POSITION, vertices.count, vertices.itemSize, vertices.array );
const faces = geometry.getIndex();
if ( faces !== null ) {
builder.AddFacesToMesh( dracoObject, faces.count / 3, faces.array );
} else {
const faces = new ( vertices.count > 65535 ? Uint32Array : Uint16Array )( vertices.count );
for ( let i = 0; i < faces.length; i ++ ) {
faces[ i ] = i;
}
builder.AddFacesToMesh( dracoObject, vertices.count, faces );
}
if ( options.exportNormals === true ) {
const normals = geometry.getAttribute( 'normal' );
if ( normals !== undefined ) {
builder.AddFloatAttributeToMesh( dracoObject, dracoEncoder.NORMAL, normals.count, normals.itemSize, normals.array );
}
}
if ( options.exportUvs === true ) {
const uvs = geometry.getAttribute( 'uv' );
if ( uvs !== undefined ) {
builder.AddFloatAttributeToMesh( dracoObject, dracoEncoder.TEX_COORD, uvs.count, uvs.itemSize, uvs.array );
}
}
if ( options.exportColor === true ) {
const colors = geometry.getAttribute( 'color' );
if ( colors !== undefined ) {
const array = createVertexColorSRGBArray( colors );
builder.AddFloatAttributeToMesh( dracoObject, dracoEncoder.COLOR, colors.count, colors.itemSize, array );
}
}
} else if ( object.isPoints === true ) {
builder = new dracoEncoder.PointCloudBuilder();
dracoObject = new dracoEncoder.PointCloud();
const vertices = geometry.getAttribute( 'position' );
builder.AddFloatAttribute( dracoObject, dracoEncoder.POSITION, vertices.count, vertices.itemSize, vertices.array );
if ( options.exportColor === true ) {
const colors = geometry.getAttribute( 'color' );
if ( colors !== undefined ) {
const array = createVertexColorSRGBArray( colors );
builder.AddFloatAttribute( dracoObject, dracoEncoder.COLOR, colors.count, colors.itemSize, array );
}
}
} else {
throw new Error( 'DRACOExporter: Unsupported object type.' );
}
//Compress using draco encoder
const encodedData = new dracoEncoder.DracoInt8Array();
//Sets the desired encoding and decoding speed for the given options from 0 (slowest speed, but the best compression) to 10 (fastest, but the worst compression).
const encodeSpeed = ( options.encodeSpeed !== undefined ) ? options.encodeSpeed : 5;
const decodeSpeed = ( options.decodeSpeed !== undefined ) ? options.decodeSpeed : 5;
encoder.SetSpeedOptions( encodeSpeed, decodeSpeed );
// Sets the desired encoding method for a given geometry.
if ( options.encoderMethod !== undefined ) {
encoder.SetEncodingMethod( options.encoderMethod );
}
// Sets the quantization (number of bits used to represent) compression options for a named attribute.
// The attribute values will be quantized in a box defined by the maximum extent of the attribute values.
if ( options.quantization !== undefined ) {
for ( let i = 0; i < 5; i ++ ) {
if ( options.quantization[ i ] !== undefined ) {
encoder.SetAttributeQuantization( i, options.quantization[ i ] );
}
}
}
let length;
if ( object.isMesh === true ) {
length = encoder.EncodeMeshToDracoBuffer( dracoObject, encodedData );
} else {
length = encoder.EncodePointCloudToDracoBuffer( dracoObject, true, encodedData );
}
dracoEncoder.destroy( dracoObject );
if ( length === 0 ) {
throw new Error( 'THREE.DRACOExporter: Draco encoding failed.' );
}
//Copy encoded data to buffer.
const outputData = new Int8Array( new ArrayBuffer( length ) );
for ( let i = 0; i < length; i ++ ) {
outputData[ i ] = encodedData.GetValue( i );
}
dracoEncoder.destroy( encodedData );
dracoEncoder.destroy( encoder );
dracoEncoder.destroy( builder );
return outputData;
}
}
function createVertexColorSRGBArray( attribute ) {
// While .drc files do not specify colorspace, the only 'official' tooling
// is PLY and OBJ converters, which use sRGB. We'll assume sRGB is expected
// for .drc files, but note that Draco buffers embedded in glTF files will
// be Linear-sRGB instead.
const _color = new Color();
const count = attribute.count;
const itemSize = attribute.itemSize;
const array = new Float32Array( count * itemSize );
for ( let i = 0, il = count; i < il; i ++ ) {
_color.fromBufferAttribute( attribute, i );
ColorManagement.fromWorkingColorSpace( _color, SRGBColorSpace );
array[ i * itemSize ] = _color.r;
array[ i * itemSize + 1 ] = _color.g;
array[ i * itemSize + 2 ] = _color.b;
if ( itemSize === 4 ) {
array[ i * itemSize + 3 ] = attribute.getW( i );
}
}
return array;
}
// Encoder methods
/**
* Edgebreaker encoding.
*
* @static
* @constant
* @type {number}
* @default 1
*/
DRACOExporter.MESH_EDGEBREAKER_ENCODING = 1;
/**
* Sequential encoding.
*
* @static
* @constant
* @type {number}
* @default 0
*/
DRACOExporter.MESH_SEQUENTIAL_ENCODING = 0;
// Geometry type
DRACOExporter.POINT_CLOUD = 0;
DRACOExporter.TRIANGULAR_MESH = 1;
// Attribute type
DRACOExporter.INVALID = - 1;
DRACOExporter.POSITION = 0;
DRACOExporter.NORMAL = 1;
DRACOExporter.COLOR = 2;
DRACOExporter.TEX_COORD = 3;
DRACOExporter.GENERIC = 4;
/**
* Export options of `DRACOExporter`.
*
* @typedef {Object} DRACOExporter~Options
* @property {number} [decodeSpeed=5] - Indicates how to tune the encoder regarding decode speed (0 gives better speed but worst quality).
* @property {number} [encodeSpeed=5] - Indicates how to tune the encoder parameters (0 gives better speed but worst quality).
* @property {number} [encoderMethod=1] - Either sequential (very little compression) or Edgebreaker. Edgebreaker traverses the triangles of the mesh in a deterministic, spiral-like way which provides most of the benefits of this data format.
* @property {Array<number>} [quantization=[ 16, 8, 8, 8, 8 ]] - Indicates the precision of each type of data stored in the draco file in the order (POSITION, NORMAL, COLOR, TEX_COORD, GENERIC).
* @property {boolean} [exportUvs=true] - Whether to export UVs or not.
* @property {boolean} [exportNormals=true] - Whether to export normals or not.
* @property {boolean} [exportColor=false] - Whether to export colors or not.
**/
export { DRACOExporter };