feat: final graph

frontend/src/hooks/useLazyEyes.ts

@@ -0,0 +1,90 @@
+import { useEffect, useRef, useState } from "react";
+
+interface LazyEyesOptions {
+  /** Reference point the eyes "live" at (viewport coords). Eyes look away from this toward the mouse. */
+  anchorRef: React.RefObject<{ x: number; y: number } | null>;
+  /** Max pixel shift for the iris (default 1.5) */
+  maxShift?: number;
+  /** Lerp ease factor 0–1 for slow drift (default 0.04) */
+  ease?: number;
+  /** Saccade threshold — when target jumps more than this, snap fast (default 0.8) */
+  saccadeThreshold?: number;
+  /** Fast ease for saccade snap (default 0.35) */
+  saccadeEase?: number;
+}
+
+/**
+ * Returns a smoothly-interpolated { x, y } offset for positioning irises
+ * that lazily track the mouse cursor relative to an anchor point.
+ *
+ * Movement model:
+ * - Small mouse moves → slow, lazy drift (ease)
+ * - Large jumps → quick saccade snap (saccadeEase), then settle
+ * - Tiny random micro-drift to avoid perfectly still eyes
+ */
+export function useLazyEyes({
+  anchorRef,
+  maxShift = 1.5,
+  ease = 0.04,
+  saccadeThreshold = 0.8,
+  saccadeEase = 0.35,
+}: LazyEyesOptions) {
+  const [offset, setOffset] = useState({ x: 0, y: 0 });
+  const targetRef = useRef({ x: 0, y: 0 });
+  const currentRef = useRef({ x: 0, y: 0 });
+  const velocityRef = useRef({ x: 0, y: 0 });
+
+  useEffect(() => {
+    const onMouseMove = (e: MouseEvent) => {
+      const anchor = anchorRef.current;
+      if (!anchor) return;
+      const dx = e.clientX - anchor.x;
+      const dy = e.clientY - anchor.y;
+      const dist = Math.sqrt(dx * dx + dy * dy) || 1;
+      targetRef.current = {
+        x: (dx / dist) * maxShift,
+        y: (dy / dist) * maxShift,
+      };
+    };
+
+    window.addEventListener("mousemove", onMouseMove);
+
+    let raf = 0;
+    const tick = () => {
+      const ec = currentRef.current;
+      const et = targetRef.current;
+      const vel = velocityRef.current;
+
+      // Distance to target
+      const dx = et.x - ec.x;
+      const dy = et.y - ec.y;
+      const dist = Math.sqrt(dx * dx + dy * dy);
+
+      // Saccade: snap fast when target jumps significantly
+      const e_ = dist > saccadeThreshold ? saccadeEase : ease;
+
+      // Apply eased movement
+      vel.x = vel.x * 0.6 + dx * e_ * 0.4;
+      vel.y = vel.y * 0.6 + dy * e_ * 0.4;
+      ec.x += vel.x;
+      ec.y += vel.y;
+
+      // Micro-drift: tiny organic tremor when nearly still
+      if (dist < 0.1) {
+        ec.x += (Math.random() - 0.5) * 0.02;
+        ec.y += (Math.random() - 0.5) * 0.02;
+      }
+
+      setOffset({ x: ec.x, y: ec.y });
+      raf = requestAnimationFrame(tick);
+    };
+    raf = requestAnimationFrame(tick);
+
+    return () => {
+      window.removeEventListener("mousemove", onMouseMove);
+      cancelAnimationFrame(raf);
+    };
+  }, [anchorRef, maxShift, ease, saccadeThreshold, saccadeEase]);
+
+  return offset;
+}