a tiny program that decides how a pixel should feel about light.
means a small piece of code run on the gpu that calculates color, lighting, or position for pixels and vertices in real time.
from coined at pixar in the 1980s for the renderman shading language, used to compute how surfaces respond to light in rendered film frames; the term migrated to real-time graphics in the 2000s once gpus got programmable enough to run similar logic per frame.
toy story renderman — pixar 1995, shading language rendered every reflective surface
minecraft shaders — community mods like sildur's add fake global illumination to blocky worlds
unreal engine 5 nanite — 2021 uses custom shaders for virtualized geometry rendering
shadertoy demos — website since 2013 where entire scenes render from one fragment shader