# Off-screen Rendering

Mesa’s off-screen interface is used for rendering into user-allocated memory without any sort of window system or operating system dependencies. That is, the GL_FRONT colorbuffer is actually a buffer in main memory, rather than a window on your display.

The OSMesa API provides three basic functions for making off-screen renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and OSMesaDestroyContext(). See the Mesa/include/GL/osmesa.h header for more information about the API functions.

The OSMesa interface may be used with the gallium software renderers:

1. LLVMpipe - this is the high-performance Gallium LLVM driver

2. Softpipe - this is the reference Gallium software driver

There are several examples of OSMesa in the mesa/demos repository.

## Building OSMesa

Configure and build Mesa with something like:

    meson setup builddir -Dosmesa=true -Dgallium-drivers=swrast -Dvulkan-drivers=[] -Dprefix=$PWD/builddir/install
    meson install -C builddir

Make sure you have LLVM installed first if you want to use the LLVMpipe driver.

When the build is complete you should find:

    $PWD/builddir/install/lib/libOSMesa.so

Set your LD_LIBRARY_PATH to point to $PWD/builddir/install to use the libraries

When you link your application, link with -lOSMesa