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logseq
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add comments for force mechanics

pull/10972/head
Morgan Plain 2023-12-21 03:04:41 +01:00 committed by Tienson Qin
parent cc38b5b48f
commit 2ee5a3f43b
1 changed files with 18 additions and 0 deletions
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18
src/main/frontend/extensions/graph/pixi.cljs
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@ -54,19 +54,34 @@
:edge {:color "#A5B4FC"}})
(defn layout!
"Node forces documentation can be read in more detail here https://d3js.org/d3-force"
[nodes links link-dist]
(let [nodes-count (count nodes)
simulation (forceSimulation nodes)]
(-> simulation
(.force "link"
;; The link force pushes linked nodes together or apart according to the desired link distance.
;; The strength of the force is proportional to the difference between the linked nodes distance
;; and the target distance, similar to a spring force.
(-> (forceLink)
(.id (fn [d] (.-id d)))
(.distance link-dist)
(.links links)))
(.force "charge"
;; The many-body (or n-body) force applies mutually amongst all nodes.
;; It can be used to simulate gravity or electrostatic charge.
(-> (forceManyBody)
;; The minimum distance between nodes over which this force is considered.
;; A minimum distance establishes an upper bound on the strength of the force between two nearby nodes, avoiding instability.
(.distanceMin 1)
;; The maximum distance between nodes over which this force is considered.
;; Specifying a finite maximum distance improves performance and produces a more localized layout.
(.distanceMax (if (> nodes-count 500) 4000 600))
;; For a cluster of nodes that is far away, the charge force can be approximated by treating the cluster as a single, larger node.
;; The theta parameter determines the accuracy of the approximation
(.theta 0.5)
;; A positive value causes nodes to attract each other, similar to gravity,
;; while a negative value causes nodes to repel each other, similar to electrostatic charge.
(.strength -600)))
(.force "collision"
(-> (forceCollide)
@ -75,6 +90,9 @@
(.force "x" (-> (forceX 0) (.strength 0.02)))
(.force "y" (-> (forceY 0) (.strength 0.02)))
(.force "center" (forceCenter))
;; The decay factor is akin to atmospheric friction; after the application of any forces during a tick,
;; each node’s velocity is multiplied by 1 - decay. As with lowering the alpha decay rate,
;; less velocity decay may converge on a better solution, but risks numerical instabilities and oscillation.
(.velocityDecay 0.8))
(reset! *simulation simulation)
simulation))