A small and flexible makefile example for a c++ game

Makefile

# Danilo Lemos - 2020
# A free to use and edit Makefile

# It compiles and links the game's 
# source code inside src/ directory.

# Change the following variables as you need.

# Compiler:
CXX = g++

# Optimization:
CXXFLAGS += -g #-O2

# Warnings:
CXXFLAGS += -Wall

# Standart:
CXXFLAGS += --std=c++11

# Libraries (SDL2 for example):
CXXFLAGS += $(shell pkg-config sdl2 --cflags)
LDFLAGS += $(shell pkg-config sdl2 --libs) -lSDL2_mixer -lSDL2_image

# Definitions:
CXXFLAGS += -DEXAMPLE_1 -DEXAMPLE_2

# Directories:
SRC_DIR = src/
BIN_DIR = bin/
BUILD_DIR = build/

# Source files:
GAME_SRC  = *.cpp */*.cpp
GAME_SRC := $(addprefix $(SRC_DIR), $(GAME_SRC))
GAME_SRC := $(wildcard $(GAME_SRC))

# Object files:
GAME_OBJ := $(basename $(GAME_SRC))
GAME_OBJ := $(subst $(SRC_DIR), ,$(GAME_OBJ))
GAME_OBJ := $(addsuffix .o, $(GAME_OBJ))
GAME_OBJ := $(addprefix $(BUILD_DIR), $(GAME_OBJ))

# Dependency files:
DEPENDENCIES := $(GAME_OBJ)
DEPENDENCIES := $(basename $(DEPENDENCIES))
DEPENDENCIES := $(addsuffix .d, $(DEPENDENCIES))

# Binary output:
GAME_BIN = $(BIN_DIR)my-game

game: $(GAME_BIN)

###########################
$(GAME_BIN): $(GAME_OBJ)
	@echo -Linking objects
	@mkdir -p $(dir $@) >/dev/null
	@$(CXX) $^ $(LDFLAGS) -o $@
###########################

###########################
-include $(DEPENDENCIES)

$(BUILD_DIR)%.o: $(SRC_DIR)%.cpp
	@echo -Compiling $<
	@mkdir -p $(dir $@) >/dev/null
	@$(CXX) $(CXXFLAGS) -I$(SRC_DIR) -o $@ -c $<
	@$(CXX) -MM -MT $@ -I$(SRC_DIR) $< > $(BUILD_DIR)$*.d
###########################

clean:
	@rm -rf $(BIN_DIR)
	@rm -rf $(BUILD_DIR)

.PHONY: game clean