copy method
Copy the parameters from the passed material into this material.
Implementation
@override
RawShaderMaterial copy(Material source) {
  super.copy(source);
  type = 'RawShaderMaterial';
  return this;
}Copy the parameters from the passed material into this material.
@override
RawShaderMaterial copy(Material source) {
  super.copy(source);
  type = 'RawShaderMaterial';
  return this;
}