code: function LGraphTextureEdges() {
              this.addInput("Tex.", "Texture");
  
              this.addOutput("Edges", "Texture");
              this.properties = {
                  invert: true,
                  threshold: false,
                  factor: 1,
                  precision: LGraphTexture.DEFAULT
              };
  
              if (!LGraphTextureEdges._shader) {
                  LGraphTextureEdges._shader = new GL.Shader(
                      Shader.SCREEN_VERTEX_SHADER,
                      LGraphTextureEdges.pixel_shader
                  );
              }
          }
docs: Texture Edges detection *****************************************