Why water is unusually expensive to fake
Water has no fixed shape: it flows around objects, forms waves, and responds when something enters it. A simulation must update that motion repeatedly, often at the same time the game is handling characters, physics, sound, and everything else. More detailed fluid methods can track moving particles or solve equations across a grid, but either approach adds work—and the water has to keep moving smoothly as the player watches.
Then comes the image. Water can reflect the sky and nearby scenery, bend the view of what lies beneath it, and change appearance with its angle and depth. Those effects depend on what is around the water, so rendering a convincing lake is not just a matter of choosing a blue color.
The useful shortcut
A game often separates what water looks like from how it behaves. A mostly flat surface can use a texture—an image mapped onto geometry—with animated ripples, reflections, and transparent-looking color added through rendering tricks. If the water is scenery rather than something the player can disturb, a full fluid simulation may add little that anyone notices.
That shortcut also gives artists control. They can make a river’s surface readable, keep a pool from obscuring important objects, or preserve a deliberate color and mood instead of letting realistic light effects dominate. The goal is not always to simulate water exactly; it is to spend computation where the player can see or feel the difference. A single convincing ripple at a character’s feet may matter more than simulating every wave across a distant lake.
