## Compiling the GtkGLExt libraries

Compiling the GtkGLExt Libraries — How to compile GtkGLExt

## Building GtkGLExt on UNIX-like systems

This chapter covers building and installing GtkGLExt on UNIX and UNIX-like systems such as Linux. Compiling GtkGLExt on Microsoft Windows is different in detail and somewhat more difficult to get going since the necessary tools aren't included with the operating system.

On UNIX-like systems GtkGLExt uses the standard GNU build system, using autoconf for package configuration and resolving portability issues, automake for building makefiles that comply with the GNU Coding Standards, and libtool for building shared libraries on multiple platforms.

If you are building GtkGLExt from the distributed source packages, then won't need these tools installed; the necessary pieces of the tools are already included in the source packages. But it's useful to know a bit about how packages that use these tools work. A source package is distributed as `tar.gz` or `tar.bz2` file which you unpack into a directory full of the source files as follows:

          tar zxvf gtkglext-x.y.z.tar.gz

          tar jxvf gtkglext-x.y.z.tar.bz2

In the toplevel of the directory that is created, there will be a shell script called `configure` which you then run to take the template makefiles called `Makefile.in` in the package and create makefiles customized for your operating system. The `configure` script can be passed various command line arguments to determine how the package is built and installed. The most commonly useful argument is the `--prefix` argument which determines where the package is installed. To install a package in `/opt/gtk` you would run configure as:

          ./configure --prefix=/opt/gtk

A full list of options can be found by running `configure` with the `--help` argument. In general, the defaults are right and should be trusted. After you've run `configure`, you then run the make command to build the package and install it.

          make
          make install

If you don't have permission to write to the directory you are installing in, you may have to change to root temporarily before running `make install`. Also, if you are installing in a system directory, on some systems (such as Linux), you will need to run ldconfig after `make install` so that the newly installed libraries will be found.

If you want to compile example programs shipped with the source package, run the following command.

          make examples

Several environment variables are useful to pass to set before running configure. `CPPFLAGS` contains options to pass to the C compiler, and is used to tell the compiler where to look for include files. The `LDFLAGS` variable is used in a similar fashion for the linker. Finally the `PKG_CONFIG_PATH` environment variable contains a search path that pkg-config (see below) uses when looking for for file describing how to compile programs using different libraries. If you were installing GTK+ and it's dependencies into `/opt/gtk`, you might want to set these variables as:

          CPPFLAGS="-I/opt/gtk/include"
          LDFLAGS="-L/opt/gtk/lib"
          PKG_CONFIG_PATH="/opt/gtk/lib/pkgconfig"
          export CPPFLAGS LDFLAGS PKG_CONFIG_PATH

You may also need to set the `LD_LIBRARY_PATH` environment variable so the systems dynamic linker can find the newly installed libraries, and the `PATH` environment program so that utility binaries installed by the various libraries will be found.

          LD_LIBRARY_PATH="/opt/gtk/lib"
          PATH="/opt/gtk/bin:$PATH"
          export LD_LIBRARY_PATH PATH

## Dependencies

Before you can compile the GtkGLExt library, you need to have various other tools and libraries installed on your system. The two tools needed during the build process (as differentiated from the tools used in when creating GTK+ mentioned above such as autoconf) are pkg-config and GNU make.

- pkg-config is a tool for tracking the compilation flags needed for libraries that is used by the GTK+ libraries. (For each library, a small `.pc` text file is installed in a standard location that contains the compilation flags needed for that library along with version number information.)

- The GtkGLExt makefiles will mostly work with different versions of make, however, there tends to be a few incompatibilities, so we recommend installing GNU make if you don't already have it on your system and using it. (It may be called gmake rather than make.)

- GTK+ -- The GIMP Toolkit -- version 2.0 or above.

- OpenGL or Mesa.

## Extra Configuration Options

In addition to the normal options, the configure script for the GtkGLExt supports the following additional arguments.

`configure` [[--with-gl-prefix=DIR]] [[--with-gl-includedir=DIR]] [[--with-gl-libdir=DIR]] [[--enable-debug=[no|minimum|yes]]] [[--disable-gtk-doc] | [--enable-gtk-doc]] [[--with-html-dir=PATH]] [[--with-gdktarget=[x11|win32]]]

`--with-gl-prefix=DIR`. Directory where OpenGL (Mesa) is installed. The default is 'auto'.

`--with-gl-includedir=DIR`. Directory where OpenGL (Mesa) header files are installed. The default is 'auto'.

`--with-gl-libdir=DIR`. Directory where OpenGL (Mesa) libraries are installed. The default is 'auto'.

`--enable-debug`. Turns on various amounts of debugging support. Setting this to 'no' disables g_assert(), g_return_if_fail(), g_return_val_if_fail() and all cast checks between different object types. Setting it to 'minimum' disables only cast checks. Setting it to 'yes' enables runtime debugging. The default is 'minimum'. Note that 'no' is fast, but dangerous as it tends to destabilize even mostly bug-free software by changing the effect of many bugs from simple warnings into fatal crashes. Thus `--enable-debug=no` should not be used for stable releases of GtkGLExt.

`--disable-gtk-doc` and `--enable-gtk-doc`. The gtk-doc package is used to generate the reference documentation included with GtkGLExt. By default support for gtk-doc is disabled because it requires various extra dependencies to be installed. If you have gtk-doc installed and are modifying GtkGLExt, you may want to enable gtk-doc support by passing in `--enable-gtk-doc`. If not enabled, pre-generated HTML files distributed with GtkGLExt will be installed.

`--with-html-dir`. Path to installed the reference documentation. The default is `${datadir}/gtk-doc/html`.

`--with-gdktarget`. Toggles between the supported backends for GdkGLExt. The default is x11, unless the platform is Windows, in which case the default is win32.