Light between the lines.

THE SYSTEM BEHIND THE SURFACE

Inside Moiré Flow.

Two sheer curtains hang one behind the other before a window. Each folds the way cloth does: its surface tilts along its own length and never stretches, so its screen position and depth have closed forms in Bessel functions, solved for each pixel by Newton's method. The threads are spaced evenly along the cloth, so on screen they crowd where a fold turns away, and the cloth there reads denser and more coloured, as sheer fabric does. Each curtain is a woven mesh: warp and weft threads cross in a square weave, passing over and under each other in turn, each a round fibre that catches the light along its middle. Where the screen can resolve them they are drawn thread by thread; where they are finer than a pixel they blend into smooth, sheer cloth, so they never shimmer. Light from the window passes through both meshes, and the back curtain shows through the front one's open weave. Room light shades one side of every fold, the valleys sit farther back, a satin sheen runs along the crests, and the front curtain's hem passes in front of the back one, catching the window light on its edge and shading the cloth behind it. Moving the pointer shifts the back curtain against the front one, as moving your head would. Pressing near the front curtain gathers its threads.

This is a cloth-and-light model, not a cloth simulation: the folds follow authored waves rather than solved dynamics, the curtains do not collide, and cloth never folds back over itself except at the hem. Threads finer than a pixel blend into smooth cloth rather than being kept sharp, so on small screens the weave reads as a soft texture.

5.571 ms GPU timestamp median; p95 5.767 ms. 1440x900 @ dpr 1.5; Apple M2 (8-core GPU), Metal driver on macOS Version 26.6.2 (Build 25G83); measured 2026-10-12. This is a recorded headless sample, not a browser FPS or mobile-performance guarantee.