is a computer graphics
architecture for Silicon Graphics computer workstations
. Elan Graphics was developed in 1991 and was available as a high-end graphics option on workstations released during the mid-1990s as part of the Express Graphics
architectures family. Elan Graphics gives the workstation real-time 2D and 3D graphics
rendering capability similar to that of even high-end PC
made over ten years after Elan's introduction, with the exception of texture mapping
, which had to be performed in software.
Elan Graphics systems consist of four Geometry Engines
capable of a combined 128 MFLOPS
and one Raster Engine
. Together, they are capable of rendering 180K Z-buffered, lit, Gourad-shaded
triangles per second. The framebuffer has 56 bits per pixel, causing 12-bits per pixel (dithered RGB 4/4/4) to be used for a double-buffered, depth buffered, RGB layout. When double-buffering isn't required, it is possible to run in full 24-bit color. Similarly, when Z-buffering is not required, a double-buffered 24-bit RGB framebuffer configuration is possible. The Elan Graphics system also implemented hardware stencil buffering by allocating 4 bits from the Z-buffer to produce a combined 20-bit Z, 4-bit stencil buffer.
Elan Graphics consists of five graphics subsystems: the Command Engine, Geometry Subsystem, Raster Engine, framebuffer
and Display Subsystem. Elan Graphics can produce resolutions up to 1280 x 1024 pixels with 24-bit color and can also process unencoded NTSC
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