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(layout): add force directed layout (#26)
this is basically an adaption from springy and as such has a mutable nature, this is abstracted in the implementation as much as possible though closes #6 Co-authored-by: Andreas Drobisch <[email protected]>
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26 changes: 25 additions & 1 deletion
26
...lowtick/graphs/editor/util/MathUtil.scala → ...a/com/flowtick/graphs/util/MathUtil.scala
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4 changes: 2 additions & 2 deletions
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editor/jvm/src/test/scala/com/flowtick/graphs/MathUtilSpec.scala
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layout/jvm/src/test/scala/com/flowtick/graphs/layout/ForceDirectedLayoutJVMSpec.scala
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,36 @@ | ||
| package com.flowtick.graphs.layout | ||
|
|
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| import com.flowtick.graphs.Graph | ||
| import org.scalatest.flatspec.AnyFlatSpec | ||
| import org.scalatest.matchers.should.Matchers | ||
| import com.flowtick.graphs.defaults._ | ||
| import com.flowtick.graphs.defaults.label._ | ||
| import org.scalatest.concurrent.ScalaFutures | ||
|
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| class ForceDirectedLayoutJVMSpec extends AnyFlatSpec with Matchers with ScalaFutures { | ||
| "Force Directed layout" should "layout plants graph" in { | ||
| val plants = Graph.fromEdges[Unit, String]( | ||
| Set( | ||
| "Norway Spruce" --> "Sicilian Fir", | ||
| "Sicilian Fir" --> "Sumatran Pine", | ||
| "Sicilian Fir" --> "Japanese Larch", | ||
| "Norway Spruce" --> "Japanese Larch", | ||
| "Norway Spruce" --> "Giant Sequoia" | ||
| ) | ||
| ) | ||
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| val config = GraphLayoutConfiguration(seed = Some(42)) | ||
| ForceDirectedLayout.layout(plants, config).futureValue should be( | ||
| GraphLayout( | ||
| nodes = Map( | ||
| "Sumatran Pine" -> DefaultGeometry(29.0, 178.0, 80.0, 40.0), | ||
| "Giant Sequoia" -> DefaultGeometry(198.0, 85.0, 80.0, 40.0), | ||
| "Sicilian Fir" -> DefaultGeometry(118.0, 0.0, 80.0, 40.0), | ||
| "Norway Spruce" -> DefaultGeometry(170.0, 204.0, 80.0, 40.0), | ||
| "Japanese Larch" -> DefaultGeometry(0.0, 34.0, 80.0, 40.0) | ||
| ), | ||
| edges = Map() | ||
| ) | ||
| ) | ||
| } | ||
| } |
192 changes: 192 additions & 0 deletions
192
layout/shared/src/main/scala/com/flowtick/graphs/layout/ForceDirectedLayout.scala
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,192 @@ | ||
| package com.flowtick.graphs.layout | ||
| import com.flowtick.graphs.util.MathUtil.Vector2 | ||
| import com.flowtick.graphs.{Edge, Graph, Labeled, Node} | ||
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| import scala.collection.mutable | ||
| import scala.concurrent.Future | ||
| import scala.util.Random | ||
|
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| final case class Point( | ||
| position: Vector2, | ||
| mass: Double, | ||
| velocity: Vector2 = Vector2.zero, | ||
| acceleration: Vector2 = Vector2.zero | ||
| ) { | ||
| def applyForce(force: Vector2): Point = copy(acceleration = acceleration + (force / mass)) | ||
| } | ||
|
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| final case class Spring(start: Point, end: Point, length: Double, stiffness: Double) { | ||
| def applyForce(amount: Double): Spring = { | ||
| val d = end.position.-(start.position) // the direction of the theSpring | ||
| val displacement = length - d.length | ||
| val direction = d.normalise | ||
|
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| copy( | ||
| start = start.applyForce(direction.times(stiffness * displacement * -amount)), | ||
| end = end.applyForce(direction.times(stiffness * displacement * amount)) | ||
| ) | ||
| } | ||
| } | ||
|
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| // adapted from https://github.com/dhotson/springy/blob/master/springy.js | ||
| class ForceDirectedLayout private ( | ||
| stiffness: Double = 400.0, | ||
| repulsion: Double = 400.0, | ||
| damping: Double = 0.5, | ||
| minEnergyThreshold: Double = 0.01, | ||
| maxSpeed: Double = Double.PositiveInfinity, | ||
| seed: Option[Long] = None, | ||
| maxTicks: Int = 1000 | ||
| ) { | ||
| private val nodePoints: mutable.Map[String, Point] = mutable.Map() | ||
| private val edgeSprings: mutable.Map[String, Spring] = mutable.Map() | ||
| private val random = seed.fold(new Random())(new Random(_)) | ||
|
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| private def point(nodeId: String): Point = | ||
| nodePoints.get(nodeId) match { | ||
| case Some(existing) => existing | ||
| case None => | ||
| val point = Point(position = Vector2.random(random), 1.0) | ||
| nodePoints += nodeId -> point | ||
| point | ||
| } | ||
|
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| private def findOutgoingSpring[E, N](g: Graph[E, N], nodeId: String): Option[Spring] = | ||
| g | ||
| .outgoing(nodeId) | ||
| .map(edge => edgeSprings.get(edge.id)) | ||
| .filter(_.isDefined) | ||
| .lastOption | ||
| .flatten | ||
|
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| private def spring[E, N](g: Graph[E, N], edge: Edge[E]): Spring = | ||
| edgeSprings.get(edge.id) match { | ||
| case Some(existing) => existing | ||
| case None => | ||
| val length = 1.0 | ||
| val connectedSpring = | ||
| findOutgoingSpring(g, edge.from).orElse(findOutgoingSpring(g, edge.to)) | ||
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| connectedSpring.getOrElse { | ||
| val newSpring = Spring( | ||
| point(edge.from), | ||
| point(edge.to), | ||
| length, | ||
| stiffness | ||
| ) | ||
| edgeSprings += edge.id -> newSpring | ||
| newSpring | ||
| } | ||
| } | ||
|
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| private def eachNode[E, N, T](g: Graph[E, N])(f: (Node[N], Point) => T): Iterable[T] = | ||
| g.nodes.map { node => | ||
| f(node, point(node.id)) | ||
| } | ||
|
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| private def eachSpring[E, N](g: Graph[E, N])(f: Spring => Spring): Unit = | ||
| g.edges.map { edge => | ||
| f(spring(g, edge)) | ||
| } | ||
|
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| def applyCoulombsLaw[E, N](g: Graph[E, N]): Iterable[Iterable[Any]] = | ||
| eachNode(g) { case (node1, point1) => | ||
| eachNode(g) { case (node2, point2) => | ||
| if (point1 != point2) { | ||
| val d = point1.position - point2.position | ||
| val distance = | ||
| d.length + 0.1 // avoid massive forces at small distances (and divide by zero) | ||
| val direction = d.normalise | ||
|
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| // apply force to each end point | ||
| nodePoints += node1.id -> point1.applyForce( | ||
| direction.times(repulsion)./(distance * distance * 0.5) | ||
| ) | ||
| nodePoints += node2.id -> point2.applyForce( | ||
| direction.times(repulsion)./(distance * distance * -0.5) | ||
| ) | ||
| } | ||
| } | ||
| } | ||
|
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| def applyHookesLaw[E, N](g: Graph[E, N]): Unit = eachSpring(g)(_.applyForce(0.5)) | ||
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| def attractToCentre[E, N](g: Graph[E, N]): Unit = | ||
| eachNode(g) { case (node, point) => | ||
| val direction = point.position.times(-1.0) | ||
| nodePoints += node.id -> point.applyForce(direction.times(repulsion / 50.0)) | ||
| } | ||
|
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| def updateVelocity[E, N](g: Graph[E, N])(timestep: Double): Unit = | ||
| eachNode(g) { case (node, point) => | ||
| val velocity = point.velocity.+(point.acceleration.times(timestep)).times(damping) | ||
|
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| val withMaximum = if (velocity.length > maxSpeed) { | ||
| point.velocity.normalise.times(maxSpeed) | ||
| } else velocity | ||
|
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| nodePoints += node.id -> point.copy(velocity = withMaximum, acceleration = Vector2.zero) | ||
| } | ||
|
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| def updatePosition[E, N](g: Graph[E, N])(timestep: Double): Unit = | ||
| eachNode(g) { case (node, point) => | ||
| nodePoints += node.id -> point.copy(position = | ||
| point.position.+(point.velocity.times(timestep)) | ||
| ) | ||
| } | ||
|
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| def totalEnergy[E, N](g: Graph[E, N]): Double = | ||
| eachNode(g) { case (_, point) => | ||
| val speed = point.velocity.length | ||
| 0.5 * point.mass * speed * speed | ||
| }.sum | ||
|
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| def tick[E, N](g: Graph[E, N])(timestep: Double): ForceDirectedLayout = { | ||
| applyCoulombsLaw(g) | ||
| applyHookesLaw(g) | ||
| attractToCentre(g) | ||
| updateVelocity(g)(timestep) | ||
| updatePosition(g)(timestep) | ||
| this | ||
| } | ||
|
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| def toLayout[E, N]( | ||
| g: Graph[E, N], | ||
| layoutConfiguration: GraphLayoutConfiguration, | ||
| stepSize: Double = 0.03 | ||
| ): GraphLayout = { | ||
| val (layout, _) = (1 to maxTicks).view | ||
| .map(step => (tick(g)(stepSize), step)) | ||
| .find { | ||
| case (layout, _) if layout.totalEnergy(g) < minEnergyThreshold => true | ||
| case _ => false | ||
| } | ||
| .getOrElse((this, maxTicks)) | ||
|
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| val scale = layoutConfiguration.scale.getOrElse(20.0) | ||
| val (minX, minY) = layout.nodePoints.values.foldLeft((0.0, 0.0)) { case ((x, y), point) => | ||
| (Math.min(x, point.position.x), Math.min(y, point.position.y)) | ||
| } | ||
|
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| val nodeGeometry = layout.nodePoints.view.map { case (key, point) => | ||
| key -> DefaultGeometry( | ||
| Math.round((point.position.x + Math.abs(minX)) * scale), | ||
| Math.round((point.position.y + Math.abs(minY)) * scale), | ||
| layoutConfiguration.nodeWidth, | ||
| layoutConfiguration.nodeHeight | ||
| ) | ||
| }.toMap | ||
|
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| GraphLayout(nodeGeometry) | ||
| } | ||
|
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| } | ||
|
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| object ForceDirectedLayout extends GraphLayoutOps { | ||
| override def layout[E, N](g: Graph[E, N], layoutConfiguration: GraphLayoutConfiguration)(implicit | ||
| edgeLabel: Labeled[Edge[E], String] | ||
| ): Future[GraphLayoutLike] = | ||
| Future.successful( | ||
| new ForceDirectedLayout(seed = layoutConfiguration.seed).toLayout(g, layoutConfiguration) | ||
| ) | ||
| } |
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