for example. In the past, many professional graphics cards supported only OpenGL. As of 2010, virtually all professional cards which work on the Windows platform will also support Direct3D. Part of this has been a change in the professional graphics market from largely Unix-based hardware like SGIs and Suns to lower cost PC-based systems, leading to the growth of Windows in this market segment, while at the same time providing a new market for OpenGL software in Unix-based consumer systems running Linux or Mac OS X. The principal historical reason for OpenGL's dominance in the professional market was performance. Many professional graphics applications (for example, Softimage|3D, Alias PowerAnimator) were originally written in IRIS GL for high-end SGI workstations, which were far more capable, both graphically and in raw CPU power, than the PCs of the time. Later, many of these were ported to OpenGL, even as the personal computer was evolving into a system powerful enough to run some professional graphics applications. Users were able to run Maya, for example, the successor to Alias PowerAnimator on either SGIs or Windows-based personal computers (and today on Linux, Mac OS X, and Windows). Price competition eventually broke SGI's dominance in the market, but the established base of OpenGL software engineers and the broadening user base for OpenGL in Apple, Linux, and other operating systems, has resulted in a market where both DirectX and OpenGL are viable, widespread APIs. The other reason for OpenGL's historic advantage was marketing and design. DirectX is a set of APIs that were not marketed for professional graphics applications. Indeed, they were not even designed for such uses. DirectX was an API designed for low-level, high-performance access to broadly available, lower-performance, consumer-priced graphics hardware for the purpose of game development. OpenGL is a much more general purpose 3D API, targeting a full range of graphics hardware from low-end commodity graphics cards up to professional and scientific graphics visualization well out of the range of the average consumer, and providing features that are not necessarily exclusive for a specific kind of user. Gaming developers typically haven't demanded as wide an API as professional graphics system developers. Many games don't need overlay planes, stencils, and so on, although this hasn't prevented some game developers from using them when available. Specifically, game designers are rarely interested in the pixel invariance demanded in certain parts of the OpenGL standards, which are conversely