Features of OpenGL
i) Based on IRIS GL
OpenGL is supported on Silicon Graphics’Integrated Rater Imaging System Graphics Library (IRIS GL). Though it would have been potential to have designed a totally new Application Programmer’sInterface (API), practice with IRIS GL offered insight into what programmers need and don’tneed in a Three Dimensional graphics API. Additional, creation of OpenGL similar to Integrated Rater Imaging System Graphics Library where feasible builds OpenGL most likely to be admitted; there are various successful IRIS GL applications, and programmers of IRIS GL will have a simple time switching to OpenGL.
A critical target of OpenGL is to offer device independence while still permitting total contact to hardware. Therefore the API gives permission to graphics operations at the lowest level that still gives device independence. Hence, OpenGL does not give a suggestion for modeling complex geometric objects.
iii) Fine-Grained Control
Due to minimize the needs on how an application utilizing the Application Programmer’s Interface must save and present its information, the API must give a suggestion to state entity parts of geometric entities and operations on them. This fine-grained control is necessary so that these mechanism and operations may be defined in any order and so that control of rendering operations is comfortable to contain the needs of various applications.
A modal Application Programmer’sInterface arises in executions in which processes function in parallel on different primitives. In that cases, a mode modify must be transmit to all processors so that all collects the new parameters before it processes its next primitive. A mode change is thus developed serially, stopping primitive processing until all processors have collected the modifications, and decreasing performance accordingly.
v) Frame buffer
Most of OpenGL needs that the graphics hardware has a frame buffer. This is a realistic condition since almost all interactive graphics run on systems with frame buffers. Some actions in OpenGL are attained only during exposing their execution using a frame buffer. While OpenGL may be applied to give data for driving such devices as vector displays, such use is minor.
vi) Not Programmable
OpenGL does not give a programming language. Its function may be organized by turning actions on or off or specifying factors to operations, but the rendering algorithms are basically fixed. One basis for this decision is that, for performance basis, graphics hardware is generally designed to apply particular operations in a defined order; changing these operations with random algorithms is generally infeasible. Programmability would variance with maintenance of the API close to the hardware and thus with the objective of maximum performance.
vii) Geometry and Images
OpenGL gives support for managing both 3D and 2D geometry. An Application Programmer’s Interface for utilize with geometry should also give guidance for reading, writing, and copying images, because geometry and images are regularly joint, as when a Three Dimensional view is laid over a background image. Various per-fragment processes that are applied to fragments beginning from geometric primitives apply uniformly well to fragments corresponding to pixels in an image, making it simple to mix images with geometry.