Makefile

# makefile which automatically adapts to new files in the source code
# also uses file compilation dependencies generated by the compiler for minimal partial rebuilds

# platform ('linux' or 'windows')
PLATFORM = linux

# binary and build/source directory name
BUILD_DIR  = build
BIN        = a.out
SRC_DIR    = src

# assign 1 for release build
RELEASE = 0

# optional dependency info
# assign 1 to use or 0 to exclude dependency
# USE_FFMPEG = 1

# non-optional dependency info
# ...
# rest are only relevant on Windows, as these dependencies are managed by Linux package managers
SDL2_DIR     = dependencies/sdl2
SDL2_TTF_DIR = dependencies/sdl2_ttf

# general compiler flags
N_CORES       = 20# use less on low RAM systems
CXX           = g++
CXXFLAGS      = -std=c++20# -shared -fPIC
WARNINGS      = -Wall -Wextra -Wshadow -pedantic -Wstrict-aliasing# -Wfloat-conversion -Wconversion -Warith-conversion -Wfloat-equal -Wold-style-cast
OPTIMIZATIONS = -O3# -march=native -mtune=native -mfma -mavx2 -ftree-vectorize -ffast-math

# release/debug build
ifeq ($(RELEASE),1)
	CXXFLAGS += -DNDEBUG
else
	CXXFLAGS += -g
endif

# include source directory for absolute path includes (relative to source dir root)
INCL += -I$(SRC_DIR)/

# manage dependency build flags
# mingw32 (for building on windows)
ifeq ($(PLATFORM),windows)
	# -mwindows prevents opening a terminal at program start-up
	# CXXFLAGS += -mwindows
	LIBS += -lmingw32
endif

# sdl2 and sdl2_ttf
ifeq ($(PLATFORM),windows)
	INCL += -I$(SDL2_DIR)/include -I$(SDL2_TTF_DIR)/include
	LIBS += -L$(SDL2_DIR)/bin -L$(SDL2_TTF_DIR)/bin -lSDL2 -lSDL2_ttf
	# needed for sdl2_ttf as in includes "SDL.h" instead of "SDL2/SDL.h"
	INCL += -I$(SDL2_DIR)/include/SDL2
	# needed for "undefined reference to 'WinMain'" error
	LIBS += -L$(SDL2_DIR)/lib -lSDL2main
else
	LIBS += -lSDL2 -lSDL2_ttf
endif

# set-up build directories and source structure info
# `SRC_SUBDIRS` includes `SRC_DIR`
SRC_SUBDIRS   = $(patsubst %,%/,$(shell find $(SRC_DIR) -type d -print))
SRC_FILES     = $(wildcard $(patsubst $(SRC_DIR)%/,$(SRC_DIR)%/*.hpp,$(SRC_SUBDIRS))) $(wildcard $(patsubst $(SRC_DIR)%/,$(SRC_DIR)%/*.cpp,$(SRC_SUBDIRS)))
TMP_FILE_DIR  = $(BUILD_DIR)/tmp
BUILD_OBJ_DIR = $(TMP_FILE_DIR)/obj
BUILD_DEP_DIR = $(TMP_FILE_DIR)/dep
BUILD_SUBDIRS = $(patsubst $(SRC_DIR)%/,$(BUILD_OBJ_DIR)%/,$(SRC_SUBDIRS)) $(patsubst $(SRC_DIR)%/,$(BUILD_DEP_DIR)%/,$(SRC_SUBDIRS))

# create an .o file for every .cpp file
ALL_OBJ    = $(patsubst $(SRC_DIR)/%.cpp,$(BUILD_OBJ_DIR)/%.o,$(wildcard $(patsubst $(SRC_DIR)%/,$(SRC_DIR)%/*.cpp,$(SRC_SUBDIRS))))
# .o files which should not be created (.cpp which should not be compiled)
FILTER_OBJ =# e.g. $(BUILD_OBJ_DIR)/main.o
# objects to compile
OBJ        = $(filter-out $(FILTER_OBJ),$(ALL_OBJ))

# command to automatically generate compile dependency data
DEPFLAGS = -MT $@ -MMD -MF $(patsubst $(BUILD_OBJ_DIR)/%.o,$(BUILD_DEP_DIR)/%.d,$@)


.PHONY: all sanitize force fresh clean valgrind lines trailing_spaces no_pragma help


all:
	# compile and link
	make -j $(N_CORES) $(BUILD_DIR)/$(BIN) --no-print-directory

	# TODO: copy dependencies (library files on Windows mostly)

	# copy resource dir
	cp -r -u rsc $(BUILD_DIR)/

	@# clean compilation files when building release
	@if [ "$(RELEASE)" == "1" ]; then \
		echo "# cleaning build files..."; \
		echo "rm -rf $(TMP_FILE_DIR)"; \
		rm -rf $(TMP_FILE_DIR); \
	fi


# build project with address sanitizer
sanitize:
	make all BUILD_DIR=$(BUILD_DIR)_asan CXXFLAGS="$(CXXFLAGS) -fsanitize=address" --no-print-directory


force:
	make -B all --no-print-directory


fresh:
	make clean --no-print-directory
	make all --no-print-directory


clean:
	rm -rf $(BUILD_DIR)
	rm -rf $(BUILD_DIR)_asan


# binary rule
$(BUILD_DIR)/$(BIN): $(OBJ)
	$(CXX) $(CXXFLAGS) $(WARNINGS) $(OPTIMIZATIONS) -o $@ $^ $(LIBS)


# the different build folders needed
$(BUILD_SUBDIRS):
	mkdir -p $@


# generic object file rule; also makes dependency files using $(DEPFLAGS)
$(BUILD_OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp | $(BUILD_SUBDIRS)
	$(CXX) $(DEPFLAGS) $(CXXFLAGS) $(INCL) $(WARNINGS) $(OPTIMIZATIONS) -c $< -o $@


# include the dependencies
include $(wildcard $(patsubst $(BUILD_OBJ_DIR)/%.o,$(BUILD_DEP_DIR)/%.d,$(OBJ)))


compile_commands.json: $(SRC_FILES) Makefile
	bear -- make -B


valgrind: all
	clear
	valgrind --leak-check=full --error-limit=no $(BUILD_DIR)/$(BIN)  #--show-reachable=yes


lines:
	wc -l $(SRC_FILES)


# note that when copy pasting the grep command, the extra $ has to be removed
trailing_spaces:
	@grep --color=auto -n -r '[[:blank:]]$$' -r $(SRC_DIR)/ Makefile || echo -e "No trailing spaces in source!\n"


# don't forget to set PROJECT_NAME='<project name>'
no_pragma:
	find $(SRC_DIR)/ -type f -exec sh -c 'if head -n 1 "$$1" | grep -q "^#pragma once$$"; then filename=$$(printf "$(PROJECT_NAME)_%s" "$${1#$(SRC_DIR)/}" | tr -c "[:alnum:]" "_" | tr "[:lower:]" "[:upper:]"); sed -i "1s,^#pragma once$$,#ifndef $${filename%.*}\n#define $${filename%.*}\n," "$$1"; echo -e "\n\n#endif  // ifndef $${filename%.*}" >> "$$1"; fi' sh {} \;


help:
	@echo The default build target is \"all\", produces the build in $(BUILD_DIR).
	@echo \ \ \"make clean\" removes all built files.
	@echo \ \ \"make force\" forces all build targets to be rebuild.
	@echo \ \ \"make fresh\" runs \"make clean\; make\", which may help with potential building problems after updating.
	@echo \ \ \"make sanitize\" builds with -fsanitize=address.
	@echo
	@echo Furthermore, some often used command are added to the makefile:
	@echo \ \ \"make compile_commands.json\" creates compile command database used by clangd\; requires bear to be installed
	@echo \ \ \"make lines\" counts the number of lines in all source files.
	@echo \ \ \"make trailing_spaces\" searches all source files for trailing whitespace characters \(whitespace characters before line end\).
	@echo \ \ \"make no_pragma PROJECT_NAME=\'\<project name\>\'\" replaces \"\#pragma once\" based include guards with \"\#ifndef ...\" based ones.