Protobuf example

components.proto

syntax = "proto2";

package tec.proto;

message Entity {
  required uint64 id = 1;
  message Component {
    message ComponentProperty {
      enum Type {
        BOOL = 0;
        STRING = 1;
        INT = 2;
        FLOAT = 3;
      }
      required Type type = 1;
      required string name = 2;
      optional bool bvalue = 3;
      optional string svalue = 4;
      optional int64 ivalue = 5;
      optional float fvalue = 6;
    }
    required string type = 1;
    repeated ComponentProperty properties = 2;
  }
  repeated Component components = 2;
}

message EntityList {
  repeated Entity entities = 1;
}

renderble.cpp

	void Renderable::Out(proto::Entity_Component* target) {
		proto::Entity_Component_ComponentProperty* prop = target->add_properties();
		prop->set_type(proto::Entity_Component_ComponentProperty_Type_STRING);
		prop->set_name("mesh_name");
		prop->set_svalue(this->mesh_name);
		prop = target->add_properties();
		prop->set_type(proto::Entity_Component_ComponentProperty_Type_STRING);
		prop->set_name("shader_name");
		prop->set_svalue(this->shader_name);
		prop = target->add_properties();
		prop->set_type(proto::Entity_Component_ComponentProperty_Type_BOOL);
		prop->set_name("hidden");
		prop->set_bvalue(this->hidden);
	}

	void Renderable::In(proto::Entity_Component* source) {
		for (int i = 0; i < source->properties_size(); ++i) {
			const proto::Entity_Component_ComponentProperty& prop = source->properties(i);
			if (prop.name() == "mesh_name") {
				if (prop.type() == proto::Entity_Component_ComponentProperty_Type_STRING) {
					this->mesh_name = prop.svalue();
				}
			}
			else if (prop.name() == "shader_name") {
				if (prop.type() == proto::Entity_Component_ComponentProperty_Type_STRING) {
					this->shader_name = prop.svalue();
				}
			}
			else if (prop.name() == "hidden") {
				if (prop.type() == proto::Entity_Component_ComponentProperty_Type_BOOL) {
					this->hidden = prop.bvalue();
				}
			}
		}
	}

Updated components

syntax = "proto2";

package tec.proto;

message Renderable {
    optional string shader_name = 1;
    optional string mesh_name = 2;
    optional bool hidden = 3;
}

message Position {
    optional float x = 1;
    optional float y = 2;
    optional float z = 3;
}

message Component {
    oneof component {
        Renderable renderable = 1;
        Position position = 2;
    }
}

message Entity {
    required uint64 id = 1;
    repeated Component components = 2;
}