three.js/examples/js/exporters/DRACOExporter.js

( function () {

	/**
 * Export draco compressed files from threejs geometry objects.
 *
 * Draco files are compressed and usually are smaller than conventional 3D file formats.
 *
 * The exporter receives a options object containing
 *  - decodeSpeed, indicates how to tune the encoder regarding decode speed (0 gives better speed but worst quality)
 *  - encodeSpeed, indicates how to tune the encoder parameters (0 gives better speed but worst quality)
 *  - encoderMethod
 *  - quantization, indicates the presision of each type of data stored in the draco file in the order (POSITION, NORMAL, COLOR, TEX_COORD, GENERIC)
 *  - exportUvs
 *  - exportNormals
 */

	/* global DracoEncoderModule */

	class DRACOExporter {

		parse( object, options = {
			decodeSpeed: 5,
			encodeSpeed: 5,
			encoderMethod: DRACOExporter.MESH_EDGEBREAKER_ENCODING,
			quantization: [ 16, 8, 8, 8, 8 ],
			exportUvs: true,
			exportNormals: true,
			exportColor: false
		} ) {

			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 ) {

						builder.AddFloatAttributeToMesh( dracoObject, dracoEncoder.COLOR, colors.count, colors.itemSize, colors.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 ) {

						builder.AddFloatAttribute( dracoObject, dracoEncoder.COLOR, colors.count, colors.itemSize, colors.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;

		}

	}

	// Encoder methods

	DRACOExporter.MESH_EDGEBREAKER_ENCODING = 1;
	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;

	THREE.DRACOExporter = DRACOExporter;

} )();