src/components/effects/GradientBlinds.test.tsx

@@ -22,6 +22,9 @@ vi.mock('ogl', () => {
     Mesh: class {
         remove() {}
     },
+    Geometry: class {
+        remove() {}
+    },
     Triangle: class {
         remove() {}
     },
@@ -129,4 +132,33 @@ describe('GradientBlinds', () => {
     unmount();
     expect(disconnectSpy).toHaveBeenCalled();
   });
+
+  it('minimizes getBoundingClientRect calls during pointer move', () => {
+    const { unmount } = render(<GradientBlinds />);
+
+    // Spy on getBoundingClientRect
+    // Note: In jsdom, canvas is an HTMLCanvasElement which inherits from HTMLElement
+    const spy = vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect');
+
+    // Trigger pointer move to clear any initial calls or verify baseline
+    // The initial render calls resize(), which calls getBoundingClientRect on container
+
+    // Clear spy history from initial render
+    spy.mockClear();
+
+    act(() => {
+      const event = new PointerEvent('pointermove', {
+        clientX: 200,
+        clientY: 200,
+        bubbles: true,
+      });
+      window.dispatchEvent(event);
+    });
+
+    // EXPECTATION: It should NOT be called.
+    // This will fail currently.
+    expect(spy).not.toHaveBeenCalled();
+
+    unmount();
+  });
 });

src/components/effects/GradientBlinds.tsx

@@ -66,6 +66,8 @@ const GradientBlinds: React.FC<GradientBlindsProps> = ({
   const mouseTargetRef = useRef<[number, number]>([0, 0]);
   const lastTimeRef = useRef<number>(0);
   const firstResizeRef = useRef<boolean>(true);
+  const rectRef = useRef<DOMRect | null>(null);
+  const scrollPosRef = useRef<{ x: number; y: number }>({ x: 0, y: 0 });
 
   useEffect(() => {
     const container = containerRef.current;
@@ -277,6 +279,10 @@ void main() {
 
     const resize = () => {
       const rect = container.getBoundingClientRect();
+      rectRef.current = rect;
+      if (typeof window !== 'undefined') {
+        scrollPosRef.current = { x: window.scrollX, y: window.scrollY };
+      }
       renderer.setSize(rect.width, rect.height);
       uniforms.iResolution.value = [gl.drawingBufferWidth, gl.drawingBufferHeight, 1];
 
@@ -303,10 +309,22 @@ void main() {
     ro.observe(container);
 
     const onPointerMove = (e: PointerEvent) => {
-      const rect = canvas.getBoundingClientRect();
       const scale = (renderer as unknown as { dpr?: number }).dpr || 1;
-      const x = (e.clientX - rect.left) * scale;
+      let x, y;
-      const y = (rect.height - (e.clientY - rect.top)) * scale;
+
+      if (rectRef.current) {
+        const dx = window.scrollX - scrollPosRef.current.x;
+        const dy = window.scrollY - scrollPosRef.current.y;
+        const rectLeft = rectRef.current.left - dx;
+        const rectTop = rectRef.current.top - dy;
+        x = (e.clientX - rectLeft) * scale;
+        y = (rectRef.current.height - (e.clientY - rectTop)) * scale;
+      } else {
+        const rect = canvas.getBoundingClientRect();
+        x = (e.clientX - rect.left) * scale;
+        y = (rect.height - (e.clientY - rect.top)) * scale;
+      }
+
       mouseTargetRef.current = [x, y];
       if (mouseDampening <= 0) {
         uniforms.iMouse.value = [x, y];