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PHIGS (Programmer's Hierarchical Interactive Graphics System) is an API standard for rendering 3D computer graphics, considered to be the 3D graphics standard for the 1980s through the early 1990s. Subsequently, a combination of features and power led to the rise of OpenGL, which became the most popular professional 3D API of the mid to late 1990s. Large vendors typically offered versions of PHIGS for their platforms, including DEC PHIGS, IBM's graPHIGS and Sun's SunPHIGS. It could also used within the X Window system, supported via PEX. PEX consisted of an extension to X, adding commands that would be forwarded from the X server to the PEX system for rendering. Workstations were placed in windows typically, but could also be forwarded to take over the whole screen, or to various printer-output devices. PHIGS was designed in the 1980s, inheriting many of its ideas from the Graphical Kernel System of the late 1970s, and became a standard by 1989: ANSI (ANSI X3.144-1988), FIPS (FIPS 153) and then ISO (ISO/IEC 9592 and ISO/IEC 9593). Due to its early gestation, the standard supports only the most basic 3D graphics, including basic geometry and meshes, and only the basic Gouraud, "Dot", and Phong shading for rendering scenes. Although PHIGS ultimately expanded to contain advanced functions (including the more accurate Phong lighting model and Data Mapping), other features considered standard by the mid-1990s were not supported (notably texture mapping), nor were many machines of the era physically capable of optimizing it to perform in real time. == Technical details == The word "hierarchical" in the name refers to a notable feature of PHIGS: unlike most graphics systems, PHIGS included a scene graph system as a part of the basic standard. Models were built up in a Centralized Structure Store (CSS), a database containing a "world" including both the drawing ''primitives'' and their ''attributes'' (color, line style, etc.). CSSes could be shared among a number of virtual devices, known under PHIGS as ''workstations'', each of which could contain any number of ''views''. Displaying graphics on the screen in PHIGS was a three-step process; first the model would be built into a CSS, then a workstation would be created and opened, and finally the model would be connected to the workstation. At that point the workstation would immediately render the model, and any future changes made to the model would instantly be reflected in all applicable workstation views. PHIGS originally lacked the capability to render illuminated scenes, and was superseded by ''PHIGS+''. PHIGS+ works in essentially the same manner, but added methods for lighting and filling surfaces within a 3D scene. PHIGS+ also introduced more advanced graphics primitives, such as Non-uniform rational B-spline (NURBS) surfaces. An ad hoc ANSI committee was formed around these proposed extensions to PHIGS, changing its name to the more descriptive and (optimistically) extensible name "PHIGS PLUS" -- "PLUS" being a slightly tongue-in-cheek acronym for "Plus Lumière Und Surfaces" (the two major areas of advancement over the base PHIGS standard). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「PHIGS」の詳細全文を読む スポンサード リンク
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