// ImGui GLFW binding with OpenGL3 + shaders
// (GLFW 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.
//  [X] Gamepad navigation mapping. Enable with 'io.NavFlags |= ImGuiNavFlags_EnableGamepad'.

// 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 GLFWwindow;

// MOD START (martin), 2018-03-09: support texture references that point to an address of a texture id
union GLTextureRef {
		int mTextureId;
		struct {
			int magic;
			unsigned int* mTextureIdPtr;
		};
};
// MOD END (martin), 2018-03-09: support texture references that point to an address of a texture id

IMGUI_API bool        ImGui_ImplGlfwGL3_Init(GLFWwindow* window, bool install_callbacks);
IMGUI_API void        ImGui_ImplGlfwGL3_Shutdown();
IMGUI_API void        ImGui_ImplGlfwGL3_NewFrame();

// Use if you want to reset your rendering device without losing ImGui state.
IMGUI_API void        ImGui_ImplGlfwGL3_InvalidateDeviceObjects();
IMGUI_API bool        ImGui_ImplGlfwGL3_CreateDeviceObjects();

// GLFW callbacks (installed by default if you enable 'install_callbacks' during initialization)
// Provided here if you want to chain callbacks.
// You can also handle inputs yourself and use those as a reference.
IMGUI_API void        ImGui_ImplGlfwGL3_MouseButtonCallback(GLFWwindow* window, int button, int action, int mods);
IMGUI_API void        ImGui_ImplGlfwGL3_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset);
IMGUI_API void        ImGui_ImplGlfwGL3_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods);
IMGUI_API void        ImGui_ImplGlfwGL3_CharCallback(GLFWwindow* window, unsigned int c);