polished simulation code

frontend/lib/math/math.js

@@ -51,6 +51,54 @@ export const Vec2 = {
         return [x / norm, y / norm]
     },
 }
+export const Vec3 = {
+    Mutate: {
+        add(target, [x, y, z]) {
+            target[0] += x
+            target[1] += y
+            target[2] += z
+
+            return target
+        },
+        scale(target, factor) {
+            target[0] *= factor
+            target[1] *= factor
+            target[2] *= factor
+
+            return target
+        },
+        normalize(target) {
+            const norm = Vec3.norm2(target)
+            target[0] /= norm
+            target[1] /= norm
+            target[2] /= norm
+
+            return target
+        },
+    },
+    distance2(v1, v2) {
+        return Vec3.norm2(Vec3.sub(v1, v2))
+    },
+    add([x1, y1, z1], [x2, y2, z2]) {
+        return [x1 + x2, y1 + y2, z1 + z2]
+    },
+    sub([x1, y1, z1], [x2, y2, z2]) {
+        return [x1 - x2, y1 - y2, z1 - z2]
+    },
+    dot([x1, y1, z1], [x2, y2, z2]) {
+        return x1 * x2 + y1 * y2 + z1 * z2
+    },
+    scale([x, y, z], factor) {
+        return [x * factor, y * factor, z * factor]
+    },
+    norm2([x, y, z]) {
+        return Math.sqrt(x ** 2 + y ** 2 + z ** 2)
+    },
+    normalize([x, y, z]) {
+        const norm = Vec3.norm2([x, y, z])
+        return [x / norm, y / norm, z / norm]
+    },
+}
 
 export function clamp(min, value, max) {
     return Math.min(max, Math.max(min, value))

frontend/src/components/KnotLayer.jsx

@@ -1,8 +1,8 @@
 import { useEffect, useRef, useState } from 'preact/hooks'
 import { resampleCurve, simplifyCurve } from '../../lib/math/curves.js'
-import { clamp, Vec2 } from '../../lib/math/math.js'
+import { Vec2 } from '../../lib/math/math.js'
 
-function createSimulation(positions, velocities, accelerations) {
+function createSimulation2d(positions, velocities, accelerations) {
     return {
         positions,
         velocities,
@@ -14,10 +14,8 @@ function createSimulation(positions, velocities, accelerations) {
             const newVelocities = Array.from({ length: n }, () => [])
 
             for (let i = 0; i < n; i++) {
-                newPositions[i][0] = this.positions[i][0] + this.velocities[i][0] + this.accelerations[i][0] * 0.5
-                newPositions[i][1] = this.positions[i][1] + this.velocities[i][1] + this.accelerations[i][1] * 0.5
-                newVelocities[i][0] = this.velocities[i][0] + (this.accelerations[i][0] + newAccelerations[i][0]) * 0.5
-                newVelocities[i][1] = this.velocities[i][1] + (this.accelerations[i][1] + newAccelerations[i][1]) * 0.5
+                newPositions[i] = Vec2.add(Vec2.add(this.positions[i], this.velocities[i]), Vec2.scale(this.accelerations[i], 0.5))
+                newVelocities[i] = Vec2.add(this.velocities[i], Vec2.scale(Vec2.add(this.accelerations[i], newAccelerations[i]), 0.5))
             }
 
             this.positions = newPositions
@@ -76,7 +74,7 @@ class KnotSimulation {
     }
 
     setPositions(positions) {
-        this.particleSimulation = createSimulation(
+        this.particleSimulation = createSimulation2d(
             positions,
             Array.from({ length: positions.length }, () => [0, 0]),
             Array.from({ length: positions.length }, () => [0, 0])