# Options (e.g. `CFLAGS=-DHAVE_ARGP make`)
#   HAVE_ARGP: use `argp` for argument parsing.

prefix ?= /usr/local
exec_prefix ?= $(prefix)
bindir ?= $(exec_prefix)/bin
datarootdir ?= $(prefix)/share
datadir ?= $(datarootdir)
mandir ?= $(datarootdir)/man
man1dir ?= $(mandir)/man1

GZIP_PROG ?= gzip -cn9
INSTALL ?= install -D
INSTALL_PROGRAM ?= $(INSTALL)
INSTALL_DATA ?= $(INSTALL) -m 644
RM ?= rm -f

CPPFLAGS := \
	-D_FORTIFY_SOURCE=2 \
	$(CPPFLAGS)
OFLAGS := -O3 \
	-falign-functions=1 \
	-falign-jumps=1 \
	-falign-loops=1 \
	-fmerge-all-constants \
	-fno-asynchronous-unwind-tables \
	-fno-ident \
	-fno-plt \
	-fno-stack-protector \
	-fno-unwind-tables \
	-fomit-frame-pointer \
	-fwhole-program \
	$(OFLAGS)
WFLAGS := \
	-Wall \
	-Werror \
	-Wextra \
	-Wformat-security \
	-Wno-ignored-optimization-argument \
	-Wno-missing-field-initializers \
	-Wno-unknown-warning-option \
	-Wsuggest-attribute=const \
	-Wsuggest-attribute=format \
	-Wsuggest-attribute=noreturn \
	-Wsuggest-attribute=pure \
	$(WFLAGS)
CFLAGS := \
	-g0 \
	-MD \
	-MP \
	-pipe \
	$(OFLAGS) \
	$(WFLAGS) \
	$(CFLAGS)
LDFLAGS := \
	-Wl,--build-id=none \
	-Wl,--gc-sections \
	-Wl,-znoexecstack \
	-Wl,-znorelro \
	-Wl,-znoseparate-code \
	$(LDFLAGS)
LDLIBS := -lGL -lglut -lm -lX11
MAKEFLAGS := \
	--jobs=$(shell nproc) \
	$(MAKEFLAGS)

.PHONY: all clean install run uninstall

all: glxgears

-include glxgears.d

run: glxgears
	vblank_mode=0 __GL_SYNC_TO_VBLANK=0 ./$<

clean:
	$(RM) glxgears glxgears.i glxgears.s glxgears.o

$(DESTDIR)$(bindir)/glxgears: glxgears
	$(INSTALL_PROGRAM) $< $@

install: $(DESTDIR)$(bindir)/glxgears

uninstall:
	$(RM) $(DESTDIR)$(bindir)/glxgears

# References:
# https://archive.mesa3d.org/demos
# https://gitlab.freedesktop.org/mesa/demos/-/blob/main/src/demos/gears.c
# https://www.gnu.org/prep/standards/html_node/Command-Variables.html
# https://www.gnu.org/prep/standards/html_node/Directory-Variables.html
# https://www.gnu.org/prep/standards/html_node/Standard-Targets.html
# https://www.gnu.org/software/make/manual/html_node/Automatic-Variables.html
# https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html