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MiniGL is a cut-down version of the OpenGL 3d graphics API. It was developed by id Software in order to provide a cross-platform hardware abstraction layer for their Quake series games, the first to directly support acceleration on graphics cards. Newer cards supporting the full OpenGL API have since made MiniGL disappear, but it is arguable that without Quake OpenGL would have disappeared in the Direct3D onslaught in the late 1990s.
OpenGL is an odd API in that it contains commands that span a wide range of "levels" with no particular layering. For instance the API includes the low-level commands for specifying geometry and positioning, but also includes high-level commands for complex models using nurbs, volumetric shaders and other features that are used only on very high-end renderings. The "basic" OpenGL API includes about 250 commands in total, of which perhaps half are rarely used.
MiniGL extracted those portions of the API that were useful in the gaming arena. This included the majority of the geometry system, including display lists, color and alpha, and texture mapping. Not all MiniGL commands were expected to be implemented in hardware, making it less than useful as a hardware abstraction layer, but over time newer cards tended to support more and more of the MiniGL specification as they moved towards full OpenGL support.
Unlike OpenGL where the use of the name requires a standardization test, MiniGL was essentially a "free for all". Vendors could support as much, or as little, of the specification that they wanted, and there was no guidance on which parts should be in software vs. hardware. For instance the early 3dfx MiniGL's did not even support the various line or point drawing commands, nor the very important display list API, both of which were implemented in software in the driver. Differences between MiniGL implementations from different companies were even more pronounced.
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