Backends: Start adding sdl2 surface

examples/example_sdl2_surface/Makefile

@@ -0,0 +1,31 @@
+# Makefile for example_sdl2_surface (MinGW)
+
+CXX = g++
+CXXFLAGS = -std=c++17 -Wall -Wformat
+INCLUDES = -I../.. -I../../backends -I/mingw64/include/SDL2
+LIBS = -lmingw32 -lSDL2main -lSDL2 -lgdi32
+
+IMGUI_DIR = ../..
+SOURCES = main.cpp
+SOURCES += $(IMGUI_DIR)/imgui.cpp $(IMGUI_DIR)/imgui_demo.cpp $(IMGUI_DIR)/imgui_draw.cpp $(IMGUI_DIR)/imgui_tables.cpp $(IMGUI_DIR)/imgui_widgets.cpp
+SOURCES += $(IMGUI_DIR)/backends/imgui_impl_sdl2.cpp
+SOURCES += $(IMGUI_DIR)/backends/imgui_impl_sdlsurface2.cpp
+
+OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
+
+%.o:%.cpp
+	$(CXX) $(CXXFLAGS) $(INCLUDES) -c -o $@ $<
+
+%.o:$(IMGUI_DIR)/%.cpp
+	$(CXX) $(CXXFLAGS) $(INCLUDES) -c -o $@ $<
+
+%.o:$(IMGUI_DIR)/backends/%.cpp
+	$(CXX) $(CXXFLAGS) $(INCLUDES) -c -o $@ $<
+
+all: example_sdl2_surface.exe
+
+example_sdl2_surface.exe: $(OBJS)
+	$(CXX) -o $@ $^ $(LIBS)
+
+clean:
+	del /Q *.o *.exe