OES_standard_derivatives WebGL extensionThe OES_standard_derivatives extension for WebGL 1.0 contexts adds the GLSL derivative functions dFdx, dFdy, and fwidth.webgl-extensionsWebGL extensionswidely2015-07-292018-01-29https://registry.khronos.org/webgl/extensions/OES_standard_derivatives/https://developer.mozilla.org/docs/Web/API/OES_standard_derivativesapi.OES_standard_derivativeshttps://nowyoucanuse.com/features--oes-standard-derivatives.html