The Codrops dual-scene fluid X-ray effect. A Stable-Fluids solver runs on ping-pong float targets; its dye density becomes the reveal mask and its velocity field a per-pixel refraction offset. A cool geometric scene swims up through a warm marbled one wherever the fluid churns, distorted like light through moving glass. Drag to stir and inject dye — when the pointer is away, two swirling sources keep the flow turbulent and alive.