Represents the input shader parameter within the visual shader graph. Returns a translated name of the current constant in the Godot Shader Language. eg. [code]"ALBEDO"[/code] if the [member input_name] equal to [code]"albedo"[/code]. One of the several input constants in lower-case style like: "vertex"([/code]VERTEX[code]) or "point_size"([code]POINT_SIZE[/code]). Emitted when input is changed via [member input_name].