three.js/examples/js/lines/LineSegmentsGeometry.js

( function () {

	var LineSegmentsGeometry = function () {

		THREE.InstancedBufferGeometry.call( this );
		this.type = 'LineSegmentsGeometry';
		var positions = [ - 1, 2, 0, 1, 2, 0, - 1, 1, 0, 1, 1, 0, - 1, 0, 0, 1, 0, 0, - 1, - 1, 0, 1, - 1, 0 ];
		var uvs = [ - 1, 2, 1, 2, - 1, 1, 1, 1, - 1, - 1, 1, - 1, - 1, - 2, 1, - 2 ];
		var index = [ 0, 2, 1, 2, 3, 1, 2, 4, 3, 4, 5, 3, 4, 6, 5, 6, 7, 5 ];
		this.setIndex( index );
		this.setAttribute( 'position', new THREE.Float32BufferAttribute( positions, 3 ) );
		this.setAttribute( 'uv', new THREE.Float32BufferAttribute( uvs, 2 ) );

	};

	LineSegmentsGeometry.prototype = Object.assign( Object.create( THREE.InstancedBufferGeometry.prototype ), {
		constructor: LineSegmentsGeometry,
		isLineSegmentsGeometry: true,
		applyMatrix4: function ( matrix ) {

			var start = this.attributes.instanceStart;
			var end = this.attributes.instanceEnd;

			if ( start !== undefined ) {

				start.applyMatrix4( matrix );
				end.applyMatrix4( matrix );
				start.needsUpdate = true;

			}

			if ( this.boundingBox !== null ) {

				this.computeBoundingBox();

			}

			if ( this.boundingSphere !== null ) {

				this.computeBoundingSphere();

			}

			return this;

		},
		setPositions: function ( array ) {

			var lineSegments;

			if ( array instanceof Float32Array ) {

				lineSegments = array;

			} else if ( Array.isArray( array ) ) {

				lineSegments = new Float32Array( array );

			}

			var instanceBuffer = new THREE.InstancedInterleavedBuffer( lineSegments, 6, 1 ); // xyz, xyz

			this.setAttribute( 'instanceStart', new THREE.InterleavedBufferAttribute( instanceBuffer, 3, 0 ) ); // xyz

			this.setAttribute( 'instanceEnd', new THREE.InterleavedBufferAttribute( instanceBuffer, 3, 3 ) ); // xyz
			//

			this.computeBoundingBox();
			this.computeBoundingSphere();
			return this;

		},
		setColors: function ( array ) {

			var colors;

			if ( array instanceof Float32Array ) {

				colors = array;

			} else if ( Array.isArray( array ) ) {

				colors = new Float32Array( array );

			}

			var instanceColorBuffer = new THREE.InstancedInterleavedBuffer( colors, 6, 1 ); // rgb, rgb

			this.setAttribute( 'instanceColorStart', new THREE.InterleavedBufferAttribute( instanceColorBuffer, 3, 0 ) ); // rgb

			this.setAttribute( 'instanceColorEnd', new THREE.InterleavedBufferAttribute( instanceColorBuffer, 3, 3 ) ); // rgb

			return this;

		},
		fromWireframeGeometry: function ( geometry ) {

			this.setPositions( geometry.attributes.position.array );
			return this;

		},
		fromEdgesGeometry: function ( geometry ) {

			this.setPositions( geometry.attributes.position.array );
			return this;

		},
		fromMesh: function ( mesh ) {

			this.fromWireframeGeometry( new THREE.WireframeGeometry( mesh.geometry ) ); // set colors, maybe

			return this;

		},
		fromLineSegments: function ( lineSegments ) {

			var geometry = lineSegments.geometry;

			if ( geometry.isGeometry ) {

				console.error( 'THREE.LineSegmentsGeometry no longer supports Geometry. Use THREE.BufferGeometry instead.' );
				return;

			} else if ( geometry.isBufferGeometry ) {

				this.setPositions( geometry.attributes.position.array ); // assumes non-indexed

			} // set colors, maybe


			return this;

		},
		computeBoundingBox: function () {

			var box = new THREE.Box3();
			return function computeBoundingBox() {

				if ( this.boundingBox === null ) {

					this.boundingBox = new THREE.Box3();

				}

				var start = this.attributes.instanceStart;
				var end = this.attributes.instanceEnd;

				if ( start !== undefined && end !== undefined ) {

					this.boundingBox.setFromBufferAttribute( start );
					box.setFromBufferAttribute( end );
					this.boundingBox.union( box );

				}

			};

		}(),
		computeBoundingSphere: function () {

			var vector = new THREE.Vector3();
			return function computeBoundingSphere() {

				if ( this.boundingSphere === null ) {

					this.boundingSphere = new THREE.Sphere();

				}

				if ( this.boundingBox === null ) {

					this.computeBoundingBox();

				}

				var start = this.attributes.instanceStart;
				var end = this.attributes.instanceEnd;

				if ( start !== undefined && end !== undefined ) {

					var center = this.boundingSphere.center;
					this.boundingBox.getCenter( center );
					var maxRadiusSq = 0;

					for ( var i = 0, il = start.count; i < il; i ++ ) {

						vector.fromBufferAttribute( start, i );
						maxRadiusSq = Math.max( maxRadiusSq, center.distanceToSquared( vector ) );
						vector.fromBufferAttribute( end, i );
						maxRadiusSq = Math.max( maxRadiusSq, center.distanceToSquared( vector ) );

					}

					this.boundingSphere.radius = Math.sqrt( maxRadiusSq );

					if ( isNaN( this.boundingSphere.radius ) ) {

						console.error( 'THREE.LineSegmentsGeometry.computeBoundingSphere(): Computed radius is NaN. The instanced position data is likely to have NaN values.', this );

					}

				}

			};

		}(),
		toJSON: function () { // todo
		},
		applyMatrix: function ( matrix ) {

			console.warn( 'THREE.LineSegmentsGeometry: applyMatrix() has been renamed to applyMatrix4().' );
			return this.applyMatrix4( matrix );

		}
	} );

	THREE.LineSegmentsGeometry = LineSegmentsGeometry;

} )();