openGL abstractiopn, segment fault!!

Makefile

@@ -0,0 +1,21 @@
+CC = g++
+CFLAGS = -Iinclude -Wall -g
+LDFLAGS = -lSDL2 -lGL -lGLEW
+
+SRC = src/main.cpp src/sdl.cpp
+OBJ = $(SRC:.cpp=.o)
+EXEC = opengl-app
+
+all: $(EXEC)
+
+$(EXEC): $(OBJ)
+	$(CC) -o $@ $^ $(LDFLAGS)
+
+%.o: %.cpp
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(OBJ) $(EXEC)
+
+run: all
+	./$(EXEC)