Elan Graphics is a

computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great de ...

architecture for

Silicon Graphics Silicon Graphics, Inc. (stylized as SiliconGraphics before 1999, later rebranded SGI, historically known as Silicon Graphics Computer Systems or SGCS) was an American high-performance computing manufacturer, producing computer hardware and sof ...

computer workstation A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workst ...

s. 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 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for th ...

rendering capability similar to that of even high-end PCs made over ten years after Elan's introduction, with the exception of

texture mapping Texture mapping is a method for mapping a texture on a computer-generated graphic. Texture here can be high frequency detail, surface texture, or color. History The original technique was pioneered by Edwin Catmull in 1974. Texture mappi ...

, which had to be performed in software. The Silicon Graphics Indigo Elan option Graphics systems consist of four GE7 Geometry Engines capable of a combined 128 MFLOPS and one RE3 Raster Engine. Together, they are capable of rendering 180K Z-buffered, lit, Gouraud-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 buffer A stencil buffer is an extra data buffer, in addition to the ''color buffer'' and ''Z-buffer'', found on modern graphics hardware. The buffer is per pixel and works on integer values, usually with a depth of one byte per pixel. The Z-buffer and ...

ing 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 HQ2 Command Engine, GE7 Geometry Subsystem, RE3 Raster Engine, VM2

framebuffer A framebuffer (frame buffer, or sometimes framestore) is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame. Mode ...

and VC1 Display Subsystem. Elan Graphics can produce resolutions up to 1280 x 1024 pixels with 24-bit color and can also process unencoded

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

and

PAL Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

analog

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...

signals. The Elan Graphics system is made up of five

daughterboard In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus s ...

s that plug into the main workstation motherboard. The Elan Graphics architecture was superseded by SGI's

Extreme Graphics Extreme Graphics is a computer graphics architecture for Silicon Graphics computer workstations. Extreme Graphics was developed in 1993 and was available as a high-end graphics option on workstations such as the Indigo2, released during the mid-1 ...

architecture on Indigo2 models and eventually by the

IMPACT Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impac ...

graphics architecture in 1995.

Features

* Subpixel positioning * Advanced lighting models: * Multiple colored light sources (up to 8) * Ambient, diffuse, and specular lighting models * Phong lighting * Spotlights * Local and infinite light source positioning * Two-sided lighting * Anti-aliased lines and points * Full scene anti-aliasing * Atmospheric effects * Sphere rendering * Pixel-blending capabilities for transparency effects * Soft shadows and depth-of-field * Texture-mapping * Multimode windowing environment * X11 drawing primitives and pixel move operations * Non-Uniform Rational B-Spline (

NURBS Non-uniform rational basis spline (NURBS) is a mathematical model using B-spline, basis splines (B-splines) that is commonly used in computer graphics for representing curves and Surface (mathematics), surfaces. It offers great flexibility and pr ...

) surfaces

References

External links

ElanTR - Elan Graphics Technical Report
{{Silicon Graphics Graphics chips SGI graphics