Merge branch 'ForceDescriptor<NodeID>'

Author: li3zhen1

Examples/ForceDirectedGraphExample/ForceDirectedGraphExample/MermaidVisualization.swift

@@ -100,7 +100,7 @@ struct MermaidVisualization: View {
 
         } force: {
             .manyBody()
-            .link(originalLength: 70.0)
+            .link(originalLength: 50.0)
             .center()
         } emittingNewNodesWithStates: { id in
             KineticState(position: getInitialPosition(id: id, r: 100))

Examples/ForceDirectedGraphExample/ForceDirectedGraphExample/MyRing.swift

@@ -51,11 +51,11 @@ struct MyRing: View {
         } force: {
             .manyBody(strength: -15)
             .link(
-                originalLength: 20.0,
-                stiffness: .weightedByDegree { _, _ in 3.0}
+                originalLength: 30.0,
+                stiffness: .weightedByDegree { _, _ in 1.0 }
             )
             .center()
-            .collide()
+//            .collide()
         }
         .graphOverlay { proxy in
             Rectangle().fill(.clear).contentShape(Rectangle())

Sources/ForceSimulation/Forces/LinkForce.swift

@@ -1,3 +1,5 @@
+import Darwin
+
 extension Kinetics {
 
     public enum LinkStiffness {
@@ -15,12 +17,12 @@ extension Kinetics {
             case .weightedByDegree(let k):
                 return link.map { l in
                     k(l, lookup)
-                        / Vector.Scalar(
+                        / (Vector.Scalar(
                             min(
                                 lookup.count[l.source, default: 0],
                                 lookup.count[l.target, default: 0]
                             )
-                        )
+                        )+1)
                 }
             }
         }
@@ -81,18 +83,14 @@ extension Kinetics {
                     assert(b != 0)
 
                     var vec =
-                        (positionBufferPointer[t] + velocityBufferPointer[t] 
-                        - positionBufferPointer[s] - velocityBufferPointer[s])
-                        // .jiggled()
+                        (positionBufferPointer[t] - positionBufferPointer[s])
                         .jiggled(by: &kinetics.randomGenerator)
 
                     var l = vec.length()
 
-                    l =
-                        (l - self.calculatedLength[i]) / l * kinetics.alpha
-                        * self.calculatedStiffness[i]
+                    l = (l - self.calculatedLength[i]) / l * self.calculatedStiffness[i] * kinetics.velocityDecay * kinetics.alpha 
 
-                    vec *= l
+                    vec *= l // * kinetics.velocityDecay
 
                     // same as d3
                     velocityBufferPointer[t] -= vec * b
@@ -101,7 +99,6 @@ extension Kinetics {
             }
         }
 
-
         @usableFromInline
         internal var links: [EdgeID<Int>]! = nil
 
@@ -144,7 +141,6 @@ extension Kinetics {
 
         }
 
-
         @inlinable
         public func dispose() {}
     }
@@ -173,7 +169,6 @@ public struct LinkLookup<NodeID: Hashable> {
 
 }
 
-
 extension Kinetics.LinkStiffness: Equatable {
     @inlinable
     public static func == (lhs: Kinetics.LinkStiffness, rhs: Kinetics.LinkStiffness) -> Bool {
@@ -196,4 +191,4 @@ extension Kinetics.LinkLength: Equatable {
             return false
         }
     }
-}
+}

Sources/ForceSimulation/Simulation.swift

@@ -63,7 +63,7 @@ where Vector: SimulatableVector & L2NormCalculatable, ForceField: ForceProtocol<
         forceField: consuming ForceField,
         initialAlpha: Vector.Scalar = 1,
         alphaMin: Vector.Scalar = 1e-3,
-        alphaDecay: Vector.Scalar = 2e-3,
+        alphaDecay: Vector.Scalar = 1e-2,
         alphaTarget: Vector.Scalar = 0.0,
         velocityDecay: Vector.Scalar = 0.6,
         position: [Vector]? = nil,