Examples: SDL: Extracted into imgui_impl_sdl.*, reused imgui_impl_opengl* files.

examples/imgui_impl_sdl2.h

@@ -0,0 +1,19 @@
+// ImGui SDL2 binding with OpenGL3
+// (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
+// (GL3W is a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc.)
+
+// Implemented features:
+//  [X] User texture binding. Cast 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
+
+// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
+// If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown().
+// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
+// https://github.com/ocornut/imgui
+
+struct SDL_Window;
+typedef union SDL_Event SDL_Event;
+
+IMGUI_API bool        ImGui_ImplSDL2_Init(SDL_Window* window);
+IMGUI_API void        ImGui_ImplSDL2_Shutdown();
+IMGUI_API void        ImGui_ImplSDL2_NewFrame(SDL_Window* window);
+IMGUI_API bool        ImGui_ImplSDL2_ProcessEvent(SDL_Event* event);