A glTF numeral 3 is lit by a spotlight that follows the pointer across the viewport, then pushed through a brightness/contrast pass and resolved by the ASCII postprocessing effect. Its character ramp is a palindrome, so the glyphs run light to dark and back to light across the shading of the form. Rendered with three.js through React Three Fiber.
One of all WebGL demos by Niccolò Fanton, from the portfolio of Niccolò Fanton. The full source code for this demo is on GitHub.