Feature: books start levitating

tv-player/src/core/animate.js

@@ -88,6 +88,65 @@ function updateVcr() {
     }
 }
 
+function updateBooks() {
+    const LEVITATE_CHANCE = 0.001; // Chance for a resting book to start levitating per frame
+    const LEVITATE_DURATION_MIN = 100; // frames
+    const LEVITATE_DURATION_MAX = 300; // frames
+    const LEVITATE_AMPLITUDE = 0.02; // Max vertical displacement
+    const LEVITATE_SPEED_FACTOR = 0.03; // Speed of oscillation
+    const START_RATE = 0.05; // How quickly a book starts to levitate
+    const RETURN_RATE = 0.1; // How quickly a book returns to original position
+    const START_DURATION = 120; // frames for the starting transition
+    const levitation = state.bookLevitation;
+
+    // Manage the global levitation state
+    if (levitation.state === 'resting') {
+        if (Math.random() < LEVITATE_CHANCE) {
+            levitation.state = 'starting';
+            levitation.timer = START_DURATION;
+        }
+    } else if (levitation.state === 'starting') {
+        levitation.timer--;
+        if (levitation.timer <= 0) {
+            levitation.state = 'levitating';
+            levitation.timer = LEVITATE_DURATION_MIN + Math.random() * (LEVITATE_DURATION_MAX - LEVITATE_DURATION_MIN);
+        }
+    } else if (levitation.state === 'levitating') {
+        levitation.timer--;
+        if (levitation.timer <= 0) {
+            levitation.state = 'returning';
+        }
+    }
+
+    // Animate books based on the global state
+    let allBooksReturned = true;
+    state.books.forEach(book => {
+        const data = book.userData;
+
+        if (levitation.state === 'starting') {
+            allBooksReturned = false;
+            book.position.y = THREE.MathUtils.lerp(book.position.y, data.originalY + LEVITATE_AMPLITUDE/2, START_RATE);
+            data.oscillationTime = 0;
+        } else if (levitation.state === 'levitating') {
+            allBooksReturned = false;
+            data.oscillationTime += LEVITATE_SPEED_FACTOR;
+            data.levitateOffset = Math.sin(data.oscillationTime) * LEVITATE_AMPLITUDE;
+            book.position.y = data.originalY + data.levitateOffset + LEVITATE_AMPLITUDE/2;
+        } else if (levitation.state === 'returning') {
+            book.position.y = THREE.MathUtils.lerp(book.position.y, data.originalY, RETURN_RATE);
+            data.levitateOffset = book.position.y - data.originalY;
+
+            if (Math.abs(data.levitateOffset) > 0.001) {
+                allBooksReturned = false;
+            }
+        }
+    });
+
+    if (levitation.state === 'returning' && allBooksReturned) {
+        levitation.state = 'resting';
+    }
+}
+
 // --- Animation Loop ---
 export function animate() {
     requestAnimationFrame(animate);
@@ -98,6 +157,7 @@ export function animate() {
     updateScreenLight();
     updateVideo();
     updateVcr();
+    updateBooks();
     updateDoor();
 
     // RENDER!