feat: defined state and state machine concepts

modules/wave_survival/state.h

@@ -0,0 +1,26 @@
+#ifndef STATE_H
+#define STATE_H
+
+#include "core/object/class_db.h"
+#include "core/object/object.h"
+class StateMachine;
+class Node;
+
+class State : public Object {
+	GDCLASS(State, Object);
+	static void _bind_methods();
+
+public:
+	virtual void set_target(Node *target) {}
+	virtual void enter_state() {}
+	virtual void exit_state() {}
+	virtual void process(double delta) {}
+	virtual String get_next_state() const;
+	void set_state_machine(StateMachine *machine);
+	StateMachine *get_state_machine() const;
+
+private:
+	StateMachine *state_machine{ nullptr };
+};
+
+#endif // !STATE_H