threejs/examples/js/lines/LineSegments2.js

( function () {

	const _start = new THREE.Vector3();
	const _end = new THREE.Vector3();
	const _start4 = new THREE.Vector4();
	const _end4 = new THREE.Vector4();
	const _ssOrigin = new THREE.Vector4();
	const _ssOrigin3 = new THREE.Vector3();
	const _mvMatrix = new THREE.Matrix4();
	const _line = new THREE.Line3();
	const _closestPoint = new THREE.Vector3();
	const _box = new THREE.Box3();
	const _sphere = new THREE.Sphere();
	const _clipToWorldVector = new THREE.Vector4();
	let _ray, _instanceStart, _instanceEnd, _lineWidth;

	// Returns the margin required to expand by in world space given the distance from the camera,
	// line width, resolution, and camera projection
	function getWorldSpaceHalfWidth( camera, distance, resolution ) {

		// transform into clip space, adjust the x and y values by the pixel width offset, then
		// transform back into world space to get world offset. Note clip space is [-1, 1] so full
		// width does not need to be halved.
		_clipToWorldVector.set( 0, 0, - distance, 1.0 ).applyMatrix4( camera.projectionMatrix );
		_clipToWorldVector.multiplyScalar( 1.0 / _clipToWorldVector.w );
		_clipToWorldVector.x = _lineWidth / resolution.width;
		_clipToWorldVector.y = _lineWidth / resolution.height;
		_clipToWorldVector.applyMatrix4( camera.projectionMatrixInverse );
		_clipToWorldVector.multiplyScalar( 1.0 / _clipToWorldVector.w );
		return Math.abs( Math.max( _clipToWorldVector.x, _clipToWorldVector.y ) );

	}

	function raycastWorldUnits( lineSegments, intersects ) {

		for ( let i = 0, l = _instanceStart.count; i < l; i ++ ) {

			_line.start.fromBufferAttribute( _instanceStart, i );
			_line.end.fromBufferAttribute( _instanceEnd, i );
			const pointOnLine = new THREE.Vector3();
			const point = new THREE.Vector3();
			_ray.distanceSqToSegment( _line.start, _line.end, point, pointOnLine );
			const isInside = point.distanceTo( pointOnLine ) < _lineWidth * 0.5;
			if ( isInside ) {

				intersects.push( {
					point,
					pointOnLine,
					distance: _ray.origin.distanceTo( point ),
					object: lineSegments,
					face: null,
					faceIndex: i,
					uv: null,
					uv2: null
				} );

			}

		}

	}

	function raycastScreenSpace( lineSegments, camera, intersects ) {

		const projectionMatrix = camera.projectionMatrix;
		const material = lineSegments.material;
		const resolution = material.resolution;
		const matrixWorld = lineSegments.matrixWorld;
		const geometry = lineSegments.geometry;
		const instanceStart = geometry.attributes.instanceStart;
		const instanceEnd = geometry.attributes.instanceEnd;
		const near = - camera.near;

		//

		// pick a point 1 unit out along the ray to avoid the ray origin
		// sitting at the camera origin which will cause "w" to be 0 when
		// applying the projection matrix.
		_ray.at( 1, _ssOrigin );

		// ndc space [ - 1.0, 1.0 ]
		_ssOrigin.w = 1;
		_ssOrigin.applyMatrix4( camera.matrixWorldInverse );
		_ssOrigin.applyMatrix4( projectionMatrix );
		_ssOrigin.multiplyScalar( 1 / _ssOrigin.w );

		// screen space
		_ssOrigin.x *= resolution.x / 2;
		_ssOrigin.y *= resolution.y / 2;
		_ssOrigin.z = 0;
		_ssOrigin3.copy( _ssOrigin );
		_mvMatrix.multiplyMatrices( camera.matrixWorldInverse, matrixWorld );
		for ( let i = 0, l = instanceStart.count; i < l; i ++ ) {

			_start4.fromBufferAttribute( instanceStart, i );
			_end4.fromBufferAttribute( instanceEnd, i );
			_start4.w = 1;
			_end4.w = 1;

			// camera space
			_start4.applyMatrix4( _mvMatrix );
			_end4.applyMatrix4( _mvMatrix );

			// skip the segment if it's entirely behind the camera
			const isBehindCameraNear = _start4.z > near && _end4.z > near;
			if ( isBehindCameraNear ) {

				continue;

			}

			// trim the segment if it extends behind camera near
			if ( _start4.z > near ) {

				const deltaDist = _start4.z - _end4.z;
				const t = ( _start4.z - near ) / deltaDist;
				_start4.lerp( _end4, t );

			} else if ( _end4.z > near ) {

				const deltaDist = _end4.z - _start4.z;
				const t = ( _end4.z - near ) / deltaDist;
				_end4.lerp( _start4, t );

			}

			// clip space
			_start4.applyMatrix4( projectionMatrix );
			_end4.applyMatrix4( projectionMatrix );

			// ndc space [ - 1.0, 1.0 ]
			_start4.multiplyScalar( 1 / _start4.w );
			_end4.multiplyScalar( 1 / _end4.w );

			// screen space
			_start4.x *= resolution.x / 2;
			_start4.y *= resolution.y / 2;
			_end4.x *= resolution.x / 2;
			_end4.y *= resolution.y / 2;

			// create 2d segment
			_line.start.copy( _start4 );
			_line.start.z = 0;
			_line.end.copy( _end4 );
			_line.end.z = 0;

			// get closest point on ray to segment
			const param = _line.closestPointToPointParameter( _ssOrigin3, true );
			_line.at( param, _closestPoint );

			// check if the intersection point is within clip space
			const zPos = THREE.MathUtils.lerp( _start4.z, _end4.z, param );
			const isInClipSpace = zPos >= - 1 && zPos <= 1;
			const isInside = _ssOrigin3.distanceTo( _closestPoint ) < _lineWidth * 0.5;
			if ( isInClipSpace && isInside ) {

				_line.start.fromBufferAttribute( instanceStart, i );
				_line.end.fromBufferAttribute( instanceEnd, i );
				_line.start.applyMatrix4( matrixWorld );
				_line.end.applyMatrix4( matrixWorld );
				const pointOnLine = new THREE.Vector3();
				const point = new THREE.Vector3();
				_ray.distanceSqToSegment( _line.start, _line.end, point, pointOnLine );
				intersects.push( {
					point: point,
					pointOnLine: pointOnLine,
					distance: _ray.origin.distanceTo( point ),
					object: lineSegments,
					face: null,
					faceIndex: i,
					uv: null,
					uv2: null
				} );

			}

		}

	}

	class LineSegments2 extends THREE.Mesh {

		constructor( geometry = new THREE.LineSegmentsGeometry(), material = new THREE.LineMaterial( {
			color: Math.random() * 0xffffff
		} ) ) {

			super( geometry, material );
			this.isLineSegments2 = true;
			this.type = 'LineSegments2';

		}

		// for backwards-compatibility, but could be a method of THREE.LineSegmentsGeometry...

		computeLineDistances() {

			const geometry = this.geometry;
			const instanceStart = geometry.attributes.instanceStart;
			const instanceEnd = geometry.attributes.instanceEnd;
			const lineDistances = new Float32Array( 2 * instanceStart.count );
			for ( let i = 0, j = 0, l = instanceStart.count; i < l; i ++, j += 2 ) {

				_start.fromBufferAttribute( instanceStart, i );
				_end.fromBufferAttribute( instanceEnd, i );
				lineDistances[ j ] = j === 0 ? 0 : lineDistances[ j - 1 ];
				lineDistances[ j + 1 ] = lineDistances[ j ] + _start.distanceTo( _end );

			}

			const instanceDistanceBuffer = new THREE.InstancedInterleavedBuffer( lineDistances, 2, 1 ); // d0, d1

			geometry.setAttribute( 'instanceDistanceStart', new THREE.InterleavedBufferAttribute( instanceDistanceBuffer, 1, 0 ) ); // d0
			geometry.setAttribute( 'instanceDistanceEnd', new THREE.InterleavedBufferAttribute( instanceDistanceBuffer, 1, 1 ) ); // d1

			return this;

		}
		raycast( raycaster, intersects ) {

			const worldUnits = this.material.worldUnits;
			const camera = raycaster.camera;
			if ( camera === null && ! worldUnits ) {

				console.error( 'LineSegments2: "Raycaster.camera" needs to be set in order to raycast against LineSegments2 while worldUnits is set to false.' );

			}

			const threshold = raycaster.params.Line2 !== undefined ? raycaster.params.Line2.threshold || 0 : 0;
			_ray = raycaster.ray;
			const matrixWorld = this.matrixWorld;
			const geometry = this.geometry;
			const material = this.material;
			_lineWidth = material.linewidth + threshold;
			_instanceStart = geometry.attributes.instanceStart;
			_instanceEnd = geometry.attributes.instanceEnd;

			// check if we intersect the sphere bounds
			if ( geometry.boundingSphere === null ) {

				geometry.computeBoundingSphere();

			}

			_sphere.copy( geometry.boundingSphere ).applyMatrix4( matrixWorld );

			// increase the sphere bounds by the worst case line screen space width
			let sphereMargin;
			if ( worldUnits ) {

				sphereMargin = _lineWidth * 0.5;

			} else {

				const distanceToSphere = Math.max( camera.near, _sphere.distanceToPoint( _ray.origin ) );
				sphereMargin = getWorldSpaceHalfWidth( camera, distanceToSphere, material.resolution );

			}

			_sphere.radius += sphereMargin;
			if ( _ray.intersectsSphere( _sphere ) === false ) {

				return;

			}

			// check if we intersect the box bounds
			if ( geometry.boundingBox === null ) {

				geometry.computeBoundingBox();

			}

			_box.copy( geometry.boundingBox ).applyMatrix4( matrixWorld );

			// increase the box bounds by the worst case line width
			let boxMargin;
			if ( worldUnits ) {

				boxMargin = _lineWidth * 0.5;

			} else {

				const distanceToBox = Math.max( camera.near, _box.distanceToPoint( _ray.origin ) );
				boxMargin = getWorldSpaceHalfWidth( camera, distanceToBox, material.resolution );

			}

			_box.expandByScalar( boxMargin );
			if ( _ray.intersectsBox( _box ) === false ) {

				return;

			}

			if ( worldUnits ) {

				raycastWorldUnits( this, intersects );

			} else {

				raycastScreenSpace( this, camera, intersects );

			}

		}

	}

	THREE.LineSegments2 = LineSegments2;

} )();