GitBook: [#345] 更新 ImGui 的使用示例

SUMMARY.md

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 ***
 
 * [MIT 6.828 OS课程](mit-6.828-os-ke-cheng.md)
+* [ImGui](imgui.md)

imgui.md

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+---
+description: 简单的 ImGui 上手教程
+---
+
+# ImGui
+
+首先需要将 ImGui 工程拷贝到本地，项目的 [Github 地址](https://github.com/ocornut/imgui)
+
+这里使用的是 [premake5](https://premake.github.io/) 的构建工具，需要下载下来，可以直接使用已经编译好的 exe 文件。这个构建是基于 lua 脚本来生成工程的，所以我们需要编写相应的 lua 脚本来生成工程。
+
+把 ImGui 下载下来之后，在项目的根目录下，新建一个 premake5.lua 脚本，内容如下：
+
+```lua
+project "ImGui"
+	kind "StaticLib"
+	language "C++"
+        staticruntime "off"
+
+	targetdir ("bin/" .. outputdir .. "/%{prj.name}")
+	objdir ("bin-int/" .. outputdir .. "/%{prj.name}")
+
+	files
+	{
+		"imconfig.h",
+		"imgui.h",
+		"imgui.cpp",
+		"imgui_draw.cpp",
+		"imgui_internal.h",
+		"imgui_tables.cpp",
+		"imgui_widgets.cpp",
+		"imstb_rectpack.h",
+		"imstb_textedit.h",
+		"imstb_truetype.h",
+		"imgui_demo.cpp"
+	}
+
+	filter "system:windows"
+		systemversion "latest"
+		cppdialect "C++17"
+
+	filter "system:linux"
+		pic "On"
+		systemversion "latest"
+		cppdialect "C++17"
+
+	filter "configurations:Debug"
+		runtime "Debug"
+		symbols "on"
+
+	filter "configurations:Release"
+		runtime "Release"
+		optimize "on"
+
+        filter "configurations:Dist"
+		runtime "Release"
+		optimize "on"
+                symbols "off"
+```
+
+如果说要将其加入到 git 项目中，需要 fork 这个仓库，然后添加 premake5.lua 这个文件，然后提交，之后再去为你的 git 项目添加 submodule 。
+
+创建主项目的 premake.lua 文件，内容如下：
+
+```lua
+workspace "gui"
+	architecture "x64"
+
+	configurations 
+	{
+		"Debug",
+		"Release",
+	}
+
+outputdir = "%{cfg.buildcfg}-%{cfg.system}-%{cfg.architecture}"
+
+IncludeDir = {}
+IncludeDir["imgui"] = "gui/vendor/imgui"
+
+include "gui/vendor/imgui"
+
+project "gui"
+	location "gui"
+	kind "ConsoleApp"
+	language "C++"
+
+	targetdir ("bin/" .. outputdir .. "/%{prj.name}")
+	objdir ("bin-int/" .. outputdir .. "/%{prj.name}")
+
+	files
+	{
+		"%{prj.name}/src/**.h",
+		"%{prj.name}/src/**.cpp"
+	}
+
+	includedirs
+	{
+		"%{prj.name}/src",
+		"%{IncludeDir.imgui}"
+	}
+
+	links 
+	{
+		"ImGui",
+	}
+
+	filter "system:windows"
+		cppdialect "C++17"
+		staticruntime "On"
+		systemversion "latest"
+
+	filter "configurations:Debug"
+		buildoptions "/MDd"
+		symbols "On"
+
+
+	filter "configurations:Release"
+		buildoptions "/MD"
+		optimize "On"
+```
+
+因为 ImGui 是需要依赖系统提供的 UI 接口的，然后去创建相应的窗口和交互信息。它支持的后台有安卓、DirectX、OpenGL、glfw、OSX、Vulkan、win32等等，所以还需要去把后台搭建好。
+
+同样需要下载 [GLFW ](https://github.com/glfw/glfw)项目，下载完成后添加 premake5.lua，内容如下：
+
+```lua
+project "GLFW"
+	kind "StaticLib"
+	language "C"
+	staticruntime "off"
+
+	targetdir ("bin/" .. outputdir .. "/%{prj.name}")
+	objdir ("bin-int/" .. outputdir .. "/%{prj.name}")
+
+	files
+	{
+		"include/GLFW/glfw3.h",
+		"include/GLFW/glfw3native.h",
+		"src/glfw_config.h",
+		"src/context.c",
+		"src/init.c",
+		"src/input.c",
+		"src/monitor.c",
+
+		"src/null_init.c",
+		"src/null_joystick.c",
+		"src/null_monitor.c",
+		"src/null_window.c",
+
+		"src/platform.c",
+		"src/vulkan.c",
+		"src/window.c",
+	}
+
+	filter "system:linux"
+		pic "On"
+
+		systemversion "latest"
+
+		files
+		{
+			"src/x11_init.c",
+			"src/x11_monitor.c",
+			"src/x11_window.c",
+			"src/xkb_unicode.c",
+			"src/posix_time.c",
+			"src/posix_thread.c",
+			"src/glx_context.c",
+			"src/egl_context.c",
+			"src/osmesa_context.c",
+			"src/linux_joystick.c"
+		}
+
+		defines
+		{
+			"_GLFW_X11"
+		}
+
+	filter "system:windows"
+		systemversion "latest"
+
+		files
+		{
+			"src/win32_init.c",
+			"src/win32_joystick.c",
+			"src/win32_module.c",
+			"src/win32_monitor.c",
+			"src/win32_time.c",
+			"src/win32_thread.c",
+			"src/win32_window.c",
+			"src/wgl_context.c",
+			"src/egl_context.c",
+			"src/osmesa_context.c"
+		}
+
+		defines 
+		{ 
+			"_GLFW_WIN32",
+			"_CRT_SECURE_NO_WARNINGS"
+		}
+
+		links
+		{
+			"Dwmapi.lib"
+		}
+
+	filter "configurations:Debug"
+		runtime "Debug"
+		symbols "on"
+
+	filter "configurations:Release"
+		runtime "Release"
+		optimize "on"
+
+	filter "configurations:Dist"
+		runtime "Release"
+		optimize "on"
+        symbols "off"
+```
+
+项目自身的 premake5.lua 如下：
+
+```lua
+workspace "gui"
+	architecture "x64"
+
+	configurations 
+	{
+		"Debug",
+		"Release",
+	}
+
+outputdir = "%{cfg.buildcfg}-%{cfg.system}-%{cfg.architecture}"
+
+IncludeDir = {}
+IncludeDir["imgui"] = "gui/vendor/imgui"
+IncludeDir["GLFW"] = "gui/vendor/GLFW/include"
+
+include "gui/vendor/GLFW"
+include "gui/vendor/imgui"
+
+project "gui"
+	location "gui"
+	kind "ConsoleApp"
+	language "C++"
+
+	targetdir ("bin/" .. outputdir .. "/%{prj.name}")
+	objdir ("bin-int/" .. outputdir .. "/%{prj.name}")
+
+	files
+	{
+		"%{prj.name}/src/**.h",
+		"%{prj.name}/src/**.cpp"
+	}
+
+	includedirs
+	{
+		"%{prj.name}/src",
+		"%{IncludeDir.imgui}",
+		"%{IncludeDir.GLFW}"
+	}
+
+	links 
+	{
+		"GLFW",
+		"ImGui",
+		"opengl32.lib"
+	}
+
+	filter "system:windows"
+		cppdialect "C++17"
+		staticruntime "On"
+		systemversion "latest"
+
+	filter "configurations:Debug"
+		buildoptions "/MDd"
+		symbols "On"
+
+
+	filter "configurations:Release"
+		buildoptions "/MD"
+		optimize "On"
+
+
+```
+
+
+