better paramters

Author: remorses

packages/core/src/lib/scroll-acceleration.ts

@@ -1,7 +1,25 @@
+/**
+ * macOS-inspired scroll acceleration.
+ *
+ * The class measures the time between consecutive scroll events and keeps a short
+ * moving window of the latest intervals. The average interval determines which
+ * multiplier to apply so that quick bursts accelerate and slower gestures stay precise.
+ *
+ * Options:
+ * - threshold1: upper bound (ms) of the "medium" band. Raise to delay fast mode.
+ * - threshold2: upper bound (ms) of the "fast" band. Lower to require tighter bursts.
+ * - multiplier1: scale for medium speed. Higher values feel more eager to accelerate.
+ * - multiplier2: scale for fast speed. Higher values make flings jump further.
+ * - baseMultiplier: scale for slow scrolling. Set to 1 for linear behaviour.
+ *
+ * Default tuning mirrors the gentle macOS-style curve: relaxed scrolling stays
+ * close to 1×, while rapid consecutive ticks climb through the medium and fast
+ * bands without sudden jumps.
+ */
 export class MacOSScrollAccel {
   private lastNow = 0
   private velocityHistory: number[] = []
-  private readonly historySize = 3
+  private readonly historySize = 3 // three-sample window smooths jitter without masking bursts
 
   constructor(
     private opts: {
@@ -14,8 +32,8 @@ export class MacOSScrollAccel {
   ) {}
 
   tick(now = Date.now()): number {
-    const threshold1 = this.opts.threshold1 ?? 150
-    const threshold2 = this.opts.threshold2 ?? 50
+    const threshold1 = this.opts.threshold1 ?? 100
+    const threshold2 = this.opts.threshold2 ?? 40
     const multiplier1 = this.opts.multiplier1 ?? 2
     const multiplier2 = this.opts.multiplier2 ?? 4
     const baseMultiplier = this.opts.baseMultiplier ?? 1
@@ -33,6 +51,7 @@ export class MacOSScrollAccel {
     const avgVelocity = this.velocityHistory.length > 0
       ? this.velocityHistory.reduce((a, b) => a + b, 0) / this.velocityHistory.length
       : Infinity
+    // lower average interval ⇒ faster gestures ⇒ higher multiplier
 
     if (avgVelocity <= threshold2) {
       return multiplier2
@@ -47,4 +66,4 @@ export class MacOSScrollAccel {
     this.lastNow = 0
     this.velocityHistory = []
   }
-}
+}