code: function (data) {
      this.attributes = this.initVariables(data, 'attribute');
      this.uniforms = this.initVariables(data, 'uniform');
      this.material = new (this.raw ? THREE.RawShaderMaterial : THREE.ShaderMaterial)({
        // attributes: this.attributes,
        uniforms: this.uniforms,
        vertexShader: this.vertexShader,
        fragmentShader: this.fragmentShader
      });
      return this.material;
    }
docs: Init handler. Similar to attachedCallback.
  Called during shader initialization and is only run once.