Creative post-processing shader effects for React Three Fiber and Three.js using GLSL and the pmndrs/postprocessing library. Covers pixelation, cell patterns (receipt bars, halftone, ASCII, SDFs, threshold matrices), trompe l'oeil illusions (LED panels, crochet, lego bricks, frosted glass), and dynamic/interactive effects (progressive depixelation, mouse trail). Use when (1) Creating custom post-processing effects with pmndrs/postprocessing Effect class, (2) Implementing pixelation or cell-based pattern shaders, (3) Building stylized visual effects like halftone, ASCII art, dithering, retro, or pixel art shaders, (4) Creating optical illusion effects (frosted glass, LED panel, lego, crochet, woven), (5) Adding dynamic/interactive post-processing (mouse-driven, time-based, progressive), (6) Working with UV remapping, SDF patterns, threshold matrices, or Blinn-Phong lighting in 2D post-processing, (7) Combining multiple shader techniques into creative stylized effects.