better maefile, avoid full recompile each time

.gitignore

@@ -5,4 +5,6 @@
 
 .vscode
 
-output/
+output/
+
+build/

Makefile

@@ -1,13 +1,35 @@
 
-BUILD_DIR = build
-EXEC_NAME = render.exe
+CXX = g++
+RM = rm -f
+CXXFLAGS = -g -O3 -Wall -Wpedantic -std=c++17 -MMD -MP
+
+EXEC = render.exe
 OUTPUT_DIR = output
 SRC_DIR = src
-SRC = $(wildcard $(SRC_DIR)/*.cpp) $(wildcard $(SRC_DIR)/**/*.cpp)
-CFLAGS = -g -O3 -Wall -Wpedantic -std=c++17
+BUILD_DIR = build
+BUILD_OBJS_DIR = $(BUILD_DIR)/binaries
+BUILD_EXEC_DIR = $(BUILD_DIR)/executable
+
+SRCS = $(wildcard $(SRC_DIR)/*.cpp) $(wildcard $(SRC_DIR)/**/*.cpp)
+OBJS =  $(patsubst %.cpp, %.o, $(SRCS))
+
+OBJS_LOCATION = $(patsubst %.o, $(BUILD_OBJS_DIR)/%.o, $(OBJS))
+DEPS =  $(patsubst %.o, %.d, $(OBJS_LOCATION))
+
+.PHONY: all clean
+
+all: $(EXEC)
+
+clean:
+	$(RM) $(OBJS_LOCATION) $(DEPS)
+
+$(EXEC): $(OBJS_LOCATION)
+	if [ ! -d $(BUILD_EXEC_DIR) ]; then mkdir $(BUILD_EXEC_DIR); fi
+	$(CXX) $(OBJS_LOCATION) $(CXXFLAGS) -I $(SRC_DIR) -o $(BUILD_EXEC_DIR)/$(EXEC)
+
+-include $(DEPS)
 
-default: render.exe
+$(BUILD_OBJS_DIR)/%.o: %.cpp Makefile
+	if [ ! -d $(dir $@) ]; then mkdir -p $(dir $@); fi
+	$(CXX) $(CXXFLAGS) -I $(SRC_DIR) -c $< -o $@
 
-$(EXEC_NAME):
-	@if [ ! -d $(BUILD_DIR) ]; then mkdir $(BUILD_DIR); fi
-	@g++ $(SRC) $(CFLAGS) -I $(SRC_DIR) -o $(BUILD_DIR)/$(EXEC_NAME)