imgui/examples/imgui_impl_opengl3.h

// ImGui Renderer for: OpenGL3 / OpenGL ES2 / OpenGL ES3 (modern OpenGL with shaders / programmatic pipeline)
// This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
// (Note: We are using GL3W as 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] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.

// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui

// About OpenGL function loaders:
// Modern OpenGL requires individual functions to be loaded manually. Helper libraries are often used for this purpose.
// Here we are using gl3w.h, which requires a call to gl3wInit(). 
// You may use another any other loader/header of your choice, such as glew, glext, glad, glLoadGen, etc.

// About GLSL version:
// The 'glsl_version' initialization parameter should be NULL (default) or a "#version XXX" string.
// On computer platform the GLSL version default to "#version 130". On OpenGL ES 3 platform it defaults to "#version 300 es"
// Only override if your GL version doesn't handle this GLSL version. See GLSL version table at the top of imgui_impl_opengl3.cpp.

IMGUI_IMPL_API bool     ImGui_ImplOpenGL3_Init(const char* glsl_version = NULL);
IMGUI_IMPL_API void     ImGui_ImplOpenGL3_Shutdown();
IMGUI_IMPL_API void     ImGui_ImplOpenGL3_NewFrame();
IMGUI_IMPL_API void     ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data);

// Called by Init/NewFrame/Shutdown
IMGUI_IMPL_API bool     ImGui_ImplOpenGL3_CreateFontsTexture();
IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyFontsTexture();
IMGUI_IMPL_API bool     ImGui_ImplOpenGL3_CreateDeviceObjects();
IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();