Add CMake project

Export Dear ImGui as CMake's ImGui package.

Options:
- ImGui_USER_CONFIG;
- ImGui_EXAMPLES;
- ImGui_BACKENDS;
- ImGui_MISC;
- ImGui_3RDPARTY;
- ImGui_OPENGL_LOADER;
- ImGui_FREETYPE;
- ImGui_TOOLS;
- ImGui_PACKAGE.

Export targets:
- ImGui::Core;
- ImGui::ImplGLUT;
- ImGui::ImplSDL2;
- ImGui::ImplGlfw;
- ImGui::ImplOpenGL2;
- ImGui::ImplOpenGL3;
- ImGui::ImplVulkan;
- ImGui::FreeType;
- ImGui::StdLib;
- ImGui::BinaryToCompressedC.

Import targets from:
- build directory;
- installed package.

Examples:
- example_null;
- example_emscripten_opengl3;
- example_glut_opengl2
- example_sdl2_opengl2;
- example_sdl2_opengl3;
- example_sdl2_vulkan;
- example_glfw_opengl2;
- example_glfw_opengl3;
- example_glfw_vulkan.

examples/CMakeLists.txt

@@ -0,0 +1,92 @@
+cmake_minimum_required(VERSION 3.1)
+
+# Fetching version from header file
+file(STRINGS ../imgui.h ImGui_VERSION_NUM_HEADER_STRING
+    REGEX "#define[ \t]+IMGUI_VERSION_NUM[ \t]+([0-9]+)"
+    LIMIT_COUNT 1)
+string(REGEX REPLACE "#define[ \t]+IMGUI_VERSION_NUM[ \t]+([0-9]+)" "\\1"
+    IMGUI_VERSION_NUM "${ImGui_VERSION_NUM_HEADER_STRING}")
+math(EXPR IMGUI_VERSION_MAJOR "${IMGUI_VERSION_NUM} / 10000")
+math(EXPR IMGUI_VERSION_MINOR "(${IMGUI_VERSION_NUM} % 10000) / 100")
+math(EXPR IMGUI_VERSION_PATCH "${IMGUI_VERSION_NUM} % 100")
+
+project(imgui_examples
+    VERSION "${IMGUI_VERSION_MAJOR}.${IMGUI_VERSION_MINOR}.${IMGUI_VERSION_PATCH}"
+    LANGUAGES CXX)
+
+get_filename_component(ImGui_SRCDIR "${CMAKE_CURRENT_LIST_DIR}" DIRECTORY)
+
+include("${CMAKE_CURRENT_LIST_DIR}/ImGuiModule.cmake")
+
+set(ImGui_OPTIONS)
+
+imgui_option(USER_CONFIG "Dear ImGui user config for include" "" STRING)
+imgui_option(EXAMPLES    "Dear ImGui example applications" ON)
+imgui_option(BACKENDS    "Dear ImGui platform and render backends" ON)
+imgui_option(MISC        "Dear ImGui misc features" ON)
+imgui_option(3RDPARTY    "Dear ImGui example dependencies" ON)
+if(EMSCRIPTEN)
+    set(ImGui_OPENGL_LOADER_DEFAULT "GLEW")
+else()
+    set(ImGui_OPENGL_LOADER_DEFAULT "GL3W")
+endif()
+imgui_option(OPENGL_LOADER
+    "Dear ImGui OpenGL loader (GL3W, GLEW, GLAD or custom header)"
+    "${ImGui_OPENGL_LOADER_DEFAULT}"
+    STRINGS "GL3W" "GLEW" "GLAD")
+imgui_option(FREETYPE    "Dear ImGui will build font atlases using FreeType instead of stb_truetype" OFF)
+imgui_option(TOOLS       "Dear ImGui auxiliary applications" OFF)
+imgui_option(PACKAGE     "Dear ImGui packaging" OFF)
+
+file(GENERATE OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/ImGuiOptions.cmake"
+    CONTENT "${ImGui_OPTIONS_CMAKE}")
+
+include("${CMAKE_CURRENT_LIST_DIR}/ImGuiTargets.cmake")
+
+set(ImGui_DIR "${CMAKE_CURRENT_LIST_DIR}")
+
+imgui_example(example_null
+    TARGETS Core)
+
+if(EMSCRIPTEN)
+    imgui_example(example_emscripten_opengl3
+        BACKENDS ImplSDL2 ImplOpenGL3)
+else()
+    imgui_example(example_glut_opengl2
+        BACKENDS ImplGLUT ImplOpenGL2)
+
+    imgui_example(example_sdl2_opengl2
+        BACKENDS ImplSDL2 ImplOpenGL2)
+
+    imgui_example(example_sdl2_opengl3
+        BACKENDS ImplSDL2 ImplOpenGL3)
+
+    imgui_example(example_sdl2_vulkan
+        BACKENDS ImplSDL2 ImplVulkan)
+
+    imgui_example(example_glfw_opengl2
+        BACKENDS ImplGlfw ImplOpenGL2)
+
+    imgui_example(example_glfw_opengl3
+        BACKENDS ImplGlfw ImplOpenGL3)
+
+    imgui_example(example_glfw_vulkan
+        BACKENDS ImplGlfw ImplVulkan)
+endif()
+
+if(NOT "${CMAKE_CURRENT_LIST_DIR}" STREQUAL "${CMAKE_CURRENT_BINARY_DIR}")
+    foreach(FILE ImGuiConfig.cmake ImGuiModule.cmake ImGuiTargets.cmake)
+        configure_file(${FILE} ${FILE} COPYONLY)
+    endforeach()
+endif()
+
+install(FILES ImGuiConfig.cmake ImGuiModule.cmake ImGuiTargets.cmake
+    "${CMAKE_CURRENT_BINARY_DIR}/ImGuiOptions.cmake"
+    DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/imgui)
+
+if(ImGui_PACKAGE)
+    if(NOT DEFINED CPACK_PACKAGE_NAME)
+        set(CPACK_PACKAGE_NAME "dear-imgui")
+    endif()
+    include(CPack)
+endif()

examples/ImGuiConfig.cmake

@@ -0,0 +1,21 @@
+if(NOT DEFINED ImGui_FIND_COMPONENTS)
+    set(ImGui_FIND_COMPONENTS Core)
+endif()
+
+include("${CMAKE_CURRENT_LIST_DIR}/ImGuiTargets.cmake")
+
+foreach(COMPONENT ${ImGui_FIND_COMPONENTS})
+    if(NOT ";${ImGui_AVAILABLE_COMPONENTS};" MATCHES ";${COMPONENT};")
+        set(ImGui_FOUND FALSE)
+        set(ImGui_NOT_FOUND_MESSAGE "Unavailable component: ${COMPONENT}.")
+    endif()
+    if(NOT ";${ImGui_SUPPORTED_COMPONENTS};" MATCHES ";${COMPONENT};")
+        set(ImGui_FOUND FALSE)
+        set(ImGui_NOT_FOUND_MESSAGE "Unsupported component: ${COMPONENT}.")
+    endif()
+endforeach()
+
+if(NOT ImGui_FOUND)
+    set(ImGui_NOT_FOUND_MESSAGE "${ImGui_NOT_FOUND_MESSAGE}\nSupported components: ${ImGui_SUPPORTED_COMPONENTS}.")
+    set(ImGui_NOT_FOUND_MESSAGE "${ImGui_NOT_FOUND_MESSAGE}\nAvailable components: ${ImGui_AVAILABLE_COMPONENTS}.")
+endif()