use make auto dependencies

Makefile

@@ -40,12 +40,14 @@ SOURCES = $(wildcard $(SRC_DIR)/*.cpp)
 OBJECTS = $(patsubst $(SRC_DIR)/%.cpp,$(OBJ_DIR)/%.o,$(SOURCES))
 
 all: $(IMGUI_OBJECTS) $(OBJ_DIR)/gl3w.o $(OBJECTS)
-	$(CXX) -o $(OBJ_DIR)/hexgame $(LDFLAGS) $(GL3W_LDFLAGS) $(OBJ_DIR)/*
+	$(CXX) -o $(OBJ_DIR)/hexgame $(LDFLAGS) $(GL3W_LDFLAGS) $(OBJ_DIR)/*.o
 	mkdir -p bin
 	mv $(OBJ_DIR)/hexgame bin
 
+-include $(OBJ_DIR)/*.d
+
 $(OBJECTS): $(OBJ_DIR)/%.o : $(SRC_DIR)/%.cpp
-	$(CXX) -c $(CXXFLAGS) $< -o $@
+	$(CXX) $(CXXFLAGS) -c -MMD $< -o $@
 
 info:
 	@echo "SOURCES:"
@@ -72,3 +74,4 @@ $(OBJ_DIR)/gl3w.o:
 .PHONY: clean
 clean:
 	rm -f bin/hexgame $(OBJ_DIR)/*
+

src/hexgame.cpp

@@ -41,7 +41,6 @@
 
 using std::vector;
 
-
 game_state* g_game_state;
 render_state* g_render_state;
 vector<Point> g_polygon_select_vertices = {Point(), Point(), Point(), Point()};