Import
FreiChenShader is an addon, and must be imported explicitly, see Installation#Addons.
import { FreiChenShader } from 'three/addons/shaders/FreiChenShader.js';Properties
.FreiChenShader : ShaderMaterial~Shader (inner, constant)
Edge Detection Shader using Frei-Chen filter. Based on http://rastergrid.com/blog/2011/01/frei-chen-edge-detector.
aspect: vec2 of (1/width, 1/height)