Glitz (software)

Glitz is an API for 3D graphics and its implementation as software library. Glitz provides hardware acceleration using OpenGL for 2D graphics.^[1] Glitz is free and open-source software, subject to the requirements of the MIT License. Development is hosted at freedesktop.org, but has largely ceased.

Facilities provided

Glitz was designed to provide the same facilities as the X Rendering Extension:

• Alpha compositing
• Anti-aliasing
• Subpixel rendering
• Rendering geometrical figures and text
• Geometric transformations such as translation, rotation and scaling

As with XRender, the key operation that Glitz provides is Porter-Duff composition.

Glitz also provides some facilities that XRender does not:

• Color gradients
• Convolution filters

All of this is implemented using OpenGL features such as multitexturing, shaders, vertex buffers, frame buffer objects. In fact, a substantial part of Glitz is a wrapper around OpenGL that allows the programmer to think in terms of "drawable surfaces" rather than windows, pbuffers or frame buffer objects.

Software that uses Glitz

Glitz is the key component of the Xgl X server, which used to be shipped with most Linux distributions. However, Xgl has now been mostly superseded by Accelerated Indirect GLX (AIGLX).^[2]

The increasingly popular cairo graphics library supports Glitz as a backend, meaning that a few lines of code will enable any of the applications and toolkits which use cairo to take advantage of graphics hardware. However, glitz support in cairo has bitrotted and does not work for the 1.8.x versions of cairo.^[3] Instead, current versions of Cairo contain an OpenGL backend.

See also

• EGL – an equivalent interface to OpenGL ES and OpenVG, used e.g. by Wayland.

References