Improve library compilation guide somewhat

Related to #1931.

docs/compile.dox

@@ -10,164 +10,156 @@ build applications that use GLFW, see @ref build_guide.
 
 @section compile_cmake Using CMake
 
-GLFW uses [CMake](https://cmake.org/) to generate project files or makefiles
-for a particular development environment.  If you are on a Unix-like system such
-as Linux or FreeBSD or have a package system like Fink, MacPorts, Cygwin or
-Homebrew, you can install its CMake package.  If not, you can download
-installers for Windows and macOS from the
-[CMake website](https://cmake.org/).
-
-@note CMake only generates project files or makefiles.  It does not compile the
-actual GLFW library.  To compile GLFW, first generate these files for your
-chosen development environment and then use them to compile the actual GLFW
-library.
-
-
-@subsection compile_deps Dependencies
+@note GLFW behaves like most other libraries that use CMake so this guide mostly
+describes the basic configure/generate/compile sequence.  If you are already
+familiar with this from other projects, you may want to focus on the @ref
+compile_deps and @ref compile_options sections for GLFW-specific information.
 
-Once you have installed CMake, make sure that all other dependencies are
-available.  On some platforms, GLFW needs a few additional packages to be
-installed.  See the section for your chosen platform and development environment
-below.
+GLFW uses [CMake](https://cmake.org/) to generate project files or makefiles
+for your chosen development environment.  To compile GLFW, first generate these
+files with CMake and then use them to compile the GLFW library. 
 
+If you are on Windows and macOS you can
+[download CMake](https://cmake.org/download/) from their site.
 
-@subsubsection compile_deps_msvc Dependencies for Visual C++ on Windows
+If you are on a Unix-like system such as Linux, FreeBSD or Cygwin or have
+a package system like Fink, MacPorts or Homebrew, you can install its CMake
+package.
 
-The Windows SDK bundled with Visual C++ already contains all the necessary
-headers, link libraries and tools except for CMake.  Move on to @ref
-compile_generate.
+CMake is a complex tool and this guide will only show a few of the possible ways
+to set up and compile GLFW.  The CMake project has their own much more detailed
+[CMake user guide](https://cmake.org/cmake/help/latest/guide/user-interaction/)
+that includes everything in this guide not specific to GLFW.  It may be a useful
+companion to this one.
 
 
-@subsubsection compile_deps_mingw Dependencies for MinGW or MinGW-w64 on Windows
+@subsection compile_deps Installing dependencies
 
-Both the MinGW and the MinGW-w64 packages already contain all the necessary
-headers, link libraries and tools except for CMake.  Move on to @ref
-compile_generate.
+The C/C++ development environments in Visual Studio, Xcode and MinGW come with
+all necessary dependencies for compiling GLFW, but on Unix-like systems like
+Linux and FreeBSD you will need a few extra packages.
 
 
-@subsubsection compile_deps_mingw_cross Dependencies for MinGW or MinGW-w64 cross-compilation
+@subsubsection compile_deps_x11 Dependencies for X11 on Unix-like systems
 
-Both Cygwin and many Linux distributions have MinGW or MinGW-w64 packages.  For
-example, Cygwin has the `mingw64-i686-gcc` and `mingw64-x86_64-gcc` packages
-for 32- and 64-bit version of MinGW-w64, while Debian GNU/Linux and derivatives
-like Ubuntu have the `mingw-w64` package for both.
+To compile GLFW for X11, you need to have the X11 development packages
+installed.  They are not needed to build or run programs that use GLFW.
 
-GLFW has CMake toolchain files in the `CMake/` directory that set up
-cross-compilation of Windows binaries.  To use these files you add an option
-when running `cmake` to generate the project files or makefiles:
+On Debian and derivates like Ubuntu the `xorg-dev` meta-package pulls in the
+development packages for all of X11.
 
 @code{.sh}
-cmake -DCMAKE_TOOLCHAIN_FILE=<toolchain-file> .
+sudo apt install xorg-dev
 @endcode
 
-The exact toolchain file to use depends on the prefix used by the MinGW or
-MinGW-w64 binaries on your system.  You can usually see this in the /usr
-directory.  For example, both the Debian/Ubuntu and Cygwin MinGW-w64 packages
-have `/usr/x86_64-w64-mingw32` for the 64-bit compilers, so the correct
-invocation would be:
+On FreeBSD the X11 headers are installed along the end-user X11 packages, so if
+you have an X server running you should have the headers as well.  If not,
+install the `xorgproto` package.
 
 @code{.sh}
-cmake -DCMAKE_TOOLCHAIN_FILE=CMake/x86_64-w64-mingw32.cmake .
+pkg install xorgproto
 @endcode
 
-For more details see the article
-[CMake Cross Compiling](https://gitlab.kitware.com/cmake/community/wikis/doc/cmake/CrossCompiling) on
-the CMake wiki.
+On Cygwin the `xorgproto` package in the Devel section of the GUI installer will
+install the headers and other development related files for all of X11.
 
-Once you have this set up, move on to @ref compile_generate.
+Once you have the required depdendencies, move on to @ref compile_generate.
 
 
-@subsubsection compile_deps_xcode Dependencies for Xcode on macOS
+@subsubsection compile_deps_wayland Dependencies for Wayland on Unix-like systems
 
-Xcode comes with all necessary tools except for CMake.  The required headers
-and libraries are included in the core macOS frameworks.  Xcode can be
-downloaded from the Mac App Store or from the ADC Member Center.
+To compile GLFW for Wayland, you need to have the Wayland and xkbcommon
+development packages installed.  They are not needed to build or run programs
+that use GLFW.
 
-Once you have Xcode installed, move on to @ref compile_generate.
+On Debian and derivates like Ubuntu you will need the `libwayland-dev`,
+`libxkbcommon-dev` and `wayland-protocols` packages.
 
+@code{.sh}
+sudo apt install libwayland-dev libxkbcommon-dev wayland-protocols
+@endcode
 
-@subsubsection compile_deps_x11 Dependencies for Linux and X11
+On FreeBSD you will need the `wayland`, `libxkbcommon` and `wayland-protocols`
+packages.
 
-To compile GLFW for X11, you need to have the X11 packages installed, as well as
-the basic development tools like GCC and make.  For example, on Ubuntu and other
-distributions based on Debian GNU/Linux, you need to install the `xorg-dev`
-package, which pulls in all X.org header packages.
+@code{.sh}
+pkg install wayland libxkbcommon wayland-protocols
+@endcode
 
-Once you have installed the necessary packages, move on to @ref
-compile_generate.
+Once you have the required depdendencies, move on to @ref compile_generate.
 
 
-@subsubsection compile_deps_wayland Dependencies for Linux and Wayland
+@subsection compile_generate Generating build files with CMake
 
-To compile GLFW for Wayland, you need to have the Wayland packages installed,
-as well as the basic development tools like GCC and make.  For example, on
-Ubuntu and other distributions based on Debian GNU/Linux, you need to install
-the `libwayland-dev` package, which contains all Wayland headers and pulls in
-wayland-scanner, as well as the `wayland-protocols` package.
+Once you have all necessary dependencies it is time to generate the project
+files or makefiles for your development environment.  CMake needs two paths for
+this:
 
-Once you have installed the necessary packages, move on to @ref
-compile_generate.
+ - the path to the root directory of the GLFW source tree (not its `src`
+   subdirectory)
+ - the path to the directory where the generated build files and compiled
+   binaries will be placed
 
+If these are the same, it is called an in-tree build, otherwise it is called an
+out-of-tree build.
 
-@subsubsection compile_deps_osmesa Dependencies for Linux and OSMesa
+Out-of-tree builds are recommended as they avoid cluttering up the source tree.
+They also allow you to have several build directories for different
+configurations all using the same source tree.
 
-To compile GLFW for OSMesa, you need to install the OSMesa library and header
-packages.  For example, on Ubuntu and other distributions based on Debian
-GNU/Linux, you need to install the `libosmesa6-dev` package.  The OSMesa library
-is required at runtime for context creation and is loaded on demand.
+A common pattern when building a single configuration is to have a build
+directory named `build` in the root of the source tree.
 
-Once you have installed the necessary packages, move on to @ref
-compile_generate.
 
+@subsubsection compile_generate_gui Generating files with the CMake GUI
 
-@subsection compile_generate Generating build files with CMake
+Start the CMake GUI and set the paths to the source and build directories
+described above.  Then press _Configure_ and _Generate_.
 
-Once you have all necessary dependencies it is time to generate the project
-files or makefiles for your development environment.  CMake needs to know two
-paths for this: the path to the _root_ directory of the GLFW source tree (i.e.
-_not_ the `src` subdirectory) and the target path for the generated files and
-compiled binaries.  If these are the same, it is called an in-tree build,
-otherwise it is called an out-of-tree build.
+If you wish change any CMake variables in the list, press _Configure_ and then
+_Generate_ to have the new values take effect.  The variable list will be
+populated after the first configure step.
 
-One of several advantages of out-of-tree builds is that you can generate files
-and compile for different development environments using a single source tree.
+By default GLFW will use X11 on Linux and other Unix-like systems other
+than macOS.  To use Wayland instead, set the `GLFW_USE_WAYLAND` option in the
+GLFW section of the variable list, then apply the new value as described above.
 
-@note This section is about generating the project files or makefiles necessary
-to compile the GLFW library, not about compiling the actual library.
+Once you have generated the project files or makefiles for your chosen
+development environment, move on to @ref compile_compile.
 
 
 @subsubsection compile_generate_cli Generating files with the CMake command-line tool
 
-To make an in-tree build, enter the _root_ directory of the GLFW source tree
-(i.e. _not_ the `src` subdirectory) and run CMake.  The current directory is
-used as target path, while the path provided as an argument is used to find the
-source tree.
+To make a build directory, pass the source and build directories to the `cmake`
+command.  These can be relative or absolute paths.  The build directory is
+created if it doesn't already exist.
 
 @code{.sh}
-cd <glfw-root-dir>
-cmake .
+cmake -S path/to/glfw -B path/to/build
 @endcode
 
-To make an out-of-tree build, make a directory outside of the source tree, enter
-it and run CMake with the (relative or absolute) path to the root of the source
-tree as an argument.
+It is common to name the build directory `build` and place it in the root of the
+source tree when only planning to build a single configuration.
 
 @code{.sh}
-mkdir glfw-build
-cd glfw-build
-cmake <glfw-root-dir>
+cd path/to/glfw
+cmake -S . -B build
 @endcode
 
-Once you have generated the project files or makefiles for your chosen
-development environment, move on to @ref compile_compile.
+Without other flags these will generate Visual Studio project files on Windows
+and makefiles on other platforms.  You can choose other targets using the `-G`
+flag.
 
+@code{.sh}
+cmake -S path/to/glfw -B path/to/build -G Xcode
+@endcode
 
-@subsubsection compile_generate_gui Generating files with the CMake GUI
+By default GLFW will use X11 on Linux and other Unix-like systems other
+than macOS.  To use Wayland instead, set the `GLFW_USE_WAYLAND` CMake option.
 
-If you are using the GUI version, choose the root of the GLFW source tree as
-source location and the same directory or another, empty directory as the
-destination for binaries.  Choose _Configure_, change any options you wish to,
-_Configure_ again to let the changes take effect and then _Generate_.
+@code{.sh}
+cmake -S path/to/glfw -B path/to/build -D GLFW_USE_WAYLAND=1
+@endcode
 
 Once you have generated the project files or makefiles for your chosen
 development environment, move on to @ref compile_compile.
@@ -177,20 +169,39 @@ development environment, move on to @ref compile_compile.
 
 You should now have all required dependencies and the project files or makefiles
 necessary to compile GLFW.  Go ahead and compile the actual GLFW library with
-these files, as you would with any other project:
+these files as you would with any other project.
+
+With Visual Studio open `GLFW.sln` and use the Build menu.  With Xcode open
+`GLFW.xcodeproj` and use the Project menu.
+
+With Linux, macOS and other forms of Unix, run `make`.
+
+@code{.sh}
+cd path/to/build
+make
+@endcode
+
+With MinGW, it is `mingw32-make`.
+
+@code{.sh}
+cd path/to/build
+mingw32-make
+@endcode
+
+Any CMake build directory can also be built with the `cmake` command and the
+`--build` flag.
 
-e.g. on linux or unix,
 @code{.sh}
-cd <glfw-root-dir>
-make install
+cmake --build path/to/build
 @endcode
-or on Windows, open the .sln file in Visual Studio and build via the file menu.
 
-Once the GLFW library is compiled, you are ready to build your applications,
+This will run the platform specific build tool the directory was generated for.
+
+Once the GLFW library is compiled you are ready to build your application,
 linking it to the GLFW library.  See @ref build_guide for more information.
 
 
-@subsection compile_options CMake options
+@section compile_options CMake options
 
 The CMake files for GLFW provide a number of options, although not all are
 available on all supported platforms.  Some of these are de facto standards
@@ -206,59 +217,103 @@ Finally, if you don't want to use any GUI, you can set options from the `cmake`
 command-line with the `-D` flag.
 
 @code{.sh}
-cmake -DBUILD_SHARED_LIBS=ON .
+cmake -S path/to/glfw -B path/to/build -D BUILD_SHARED_LIBS=ON
 @endcode
 
 
-@subsubsection compile_options_shared Shared CMake options
+@subsection compile_options_shared Shared CMake options
 
 @anchor BUILD_SHARED_LIBS
 __BUILD_SHARED_LIBS__ determines whether GLFW is built as a static
-library or as a DLL / shared library / dynamic library.
+library or as a DLL / shared library / dynamic library.  This is disabled by
+default, producing a static GLFW library.
 
 @anchor GLFW_BUILD_EXAMPLES
 __GLFW_BUILD_EXAMPLES__ determines whether the GLFW examples are built
 along with the library.  This is enabled by default unless GLFW is being built
-as a sub-project.
+as a sub-project of a larger CMake project.
 
 @anchor GLFW_BUILD_TESTS
 __GLFW_BUILD_TESTS__ determines whether the GLFW test programs are
 built along with the library.  This is enabled by default unless GLFW is being
-built as a sub-project.
+built as a sub-project of a larger CMake project.
 
 @anchor GLFW_BUILD_DOCS
 __GLFW_BUILD_DOCS__ determines whether the GLFW documentation is built along
-with the library.
+with the library.  This is enabled by default if
+[Doxygen](https://www.doxygen.nl/) is found by CMake during configuration.
 
 @anchor GLFW_VULKAN_STATIC
 __GLFW_VULKAN_STATIC__ determines whether to use the Vulkan loader linked
-directly with the application.
+directly with the application.  This is disabled by default.
 
 
-@subsubsection compile_options_win32 Windows specific CMake options
+@subsection compile_options_win32 Windows specific CMake options
 
 @anchor USE_MSVC_RUNTIME_LIBRARY_DLL
 __USE_MSVC_RUNTIME_LIBRARY_DLL__ determines whether to use the DLL version or the
-static library version of the Visual C++ runtime library.  If set to `ON`, the
-DLL version of the Visual C++ library is used.
+static library version of the Visual C++ runtime library.  When enabled, the
+DLL version of the Visual C++ library is used.  This is enabled by default.
 
-@note On CMake 3.15 and later you can set the
+On CMake 3.15 and later you can set the standard CMake
 [CMAKE_MSVC_RUNTIME_LIBRARY](https://cmake.org/cmake/help/latest/variable/CMAKE_MSVC_RUNTIME_LIBRARY.html)
-variable instead of this option.
+variable instead of this GLFW-specific option.
 
 @anchor GLFW_USE_HYBRID_HPG
 __GLFW_USE_HYBRID_HPG__ determines whether to export the `NvOptimusEnablement` and
 `AmdPowerXpressRequestHighPerformance` symbols, which force the use of the
 high-performance GPU on Nvidia Optimus and AMD PowerXpress systems.  These symbols
 need to be exported by the EXE to be detected by the driver, so the override
-will not work if GLFW is built as a DLL.
+will not work if GLFW is built as a DLL.  This is disabled by default, letting
+the operating system and driver decide.
+
+
+@subsection compile_options_wayland Wayland specific CMake options
+
+@anchor GLFW_USE_WAYLAND
+__GLFW_USE_WAYLAND__ determines whether to compile the library for Wayland.
+This option is only available on Linux and other Unix-like systems other than
+macOS.  This is disabled by default.
+
+
+@section compile_mingw_cross Cross-compilation with CMake and MinGW
+
+Both Cygwin and many Linux distributions have MinGW or MinGW-w64 packages.  For
+example, Cygwin has the `mingw64-i686-gcc` and `mingw64-x86_64-gcc` packages
+for 32- and 64-bit version of MinGW-w64, while Debian GNU/Linux and derivatives
+like Ubuntu have the `mingw-w64` package for both.
+
+GLFW has CMake toolchain files in the `CMake` subdirectory that set up
+cross-compilation of Windows binaries.  To use these files you set the
+`CMAKE_TOOLCHAIN_FILE` CMake variable with the `-D` flag add an option when
+configuring and generating the build files.
+
+@code{.sh}
+cmake -S path/to/glfw -B path/to/build -D CMAKE_TOOLCHAIN_FILE=path/to/file
+@endcode
+
+The exact toolchain file to use depends on the prefix used by the MinGW or
+MinGW-w64 binaries on your system.  You can usually see this in the /usr
+directory.  For example, both the Ubuntu and Cygwin MinGW-w64 packages have
+`/usr/x86_64-w64-mingw32` for the 64-bit compilers, so the correct invocation
+would be:
+
+@code{.sh}
+cmake -S path/to/glfw -B path/to/build -D CMAKE_TOOLCHAIN_FILE=CMake/x86_64-w64-mingw32.cmake
+@endcode
+
+The path to the toolchain file is relative to the path to the GLFW source tree
+passed to the `-S` flag, not to the current directory.
+
+For more details see the
+[CMake toolchain guide](https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html).
 
 
 @section compile_manual Compiling GLFW manually
 
 If you wish to compile GLFW without its CMake build environment then you will
 have to do at least some of the platform detection yourself.  GLFW needs
-a configuration macro to be defined in order to know what window system it's
+a configuration macro to be defined in order to know what window system it is
 being compiled for and also has optional, platform-specific ones for various
 features.
 
@@ -290,11 +345,6 @@ of @b _GLFW_VULKAN_LIBRARY, @b _GLFW_EGL_LIBRARY, @b _GLFW_GLX_LIBRARY, @b
 _GLFW_OSMESA_LIBRARY, @b _GLFW_OPENGL_LIBRARY, @b _GLFW_GLESV1_LIBRARY and @b
 _GLFW_GLESV2_LIBRARY.  Otherwise, GLFW will use the built-in default names.
 
-For the EGL context creation API, the following options are available:
-
- - @b _GLFW_USE_EGLPLATFORM_H to use an existing `EGL/eglplatform.h` header file
-   for native handle types (fallback)
-
 @note None of the @ref build_macros may be defined during the compilation of
 GLFW.  If you define any of these in your build files, make sure they are not
 applied to the GLFW sources.