OpenGL Documentation
- Current OpenGL Specifications
- Way cool, way fast OpenGL rendering techniques 12/97
- OpenGL and Windows NT,
Developer News, 9/98
This is the first of a two-part article. Issue covered include
OpenGL rendering, OpenGL in standard
Windows®, and
the integration of OpenGL with the
Microsoft® Foundation Classes.
- www.opengl.org is
THE single most content-rich source
on the web
Document Abstracts/Overviews:
- OpenGL Specification:
The OpenGL Graphics System: A Specification
Version 1.2, March 16, 1998
Version 1.1, March 4, 1997
Introduction:
This document describes the OpenGL graphics system: what it
is, how it acts, and what is required to implement it. We
assume that the reader has at least a rudimentary
understanding of computer graphics. This means familiarity
with the essentials of computer graphics algorithms as well
as familiarity with basic graphics hardware and associated
terms. . . .
1.2 What is the OpenGL Graphics System?
OpenGL (for "Open Graphics Library") is a software interface
to graphics hardware. The interface consists of a set of
several hundred procedures and functions that allow a
programmer to specify the objects and operations involved in
producing high-quality graphical images, specifically color
images of three-dimensional objects.
Most of OpenGL requires that the graphics hardware contain
a framebuffer. Many OpenGL calls pertain to drawing objects
such as points, lines, polygons, and bitmaps, but the way
that some of this drawing occurs (such as when antialiasing
or texturing is enabled) relies on the existence of a
framebuffer. Further, some of OpenGL is specifically
concerned with framebuffer manipulation. . . .
1.5. Our View
We view OpenGL as a state machine that controls a set of specific
drawing operations. This model should engender a specification
that satisfies the needs of both programmers and implementors. It
does not, however, necessarily provide a model for
implementation. An implementation must produce results conforming
to those produced by the specified methods, but there may be ways
to carry out a particular computation that are more efficient
than the one specified.
- GLU Specification:
The OpenGL(TM) Graphics System Utility Library
Version 1.2, March 29, 1997
Overview:
The GL Utilities (GLU) library is a set of routines designed to
complement the OpenGL graphics system by providing support for
mipmapping, matrix manip-ulation, polygon tessellation, quadrics,
NURBS, and error handling. Mipmapping routines include image
scaling and automatic mipmap generation. A variety of matrix
manipulation functions build projection and viewing matrices,
or project vertices from one coordinate system to another. Polygon
tessellation routines convert concave polygons into triangles for
easy rendering. Quadrics support renders a few basic quadrics such
as spheres and cones. NURBS code maps complicated NURBS curves and
trimmed surfaces into simpler OpenGL evaluators. Lastly, an error
lookup routine translates OpenGL and GLU error codes into strings. GLU
library routines may call OpenGL library routines. Thus, an OpenGL context
should be made current before calling any GLU functions. Otherwise an OpenGL
error may occur.
All GLU routines, except for the initialization routines listed in
Section 2, may be called during display list creation. This will
cause any OpenGLcommands that are issued as a result of the call to
be stored in the display list. The result of calling the
intialization routines after glNewList is undefined.
- GLX Specification:
OpenGL Graphics with the X Window System
Version 1.3, July 2, 1998
Version 1.2, March 4, 1997
Version 1.1, January 1, 1995
Overview:
This document describes GLX, the OpenGL extension to the X
Window System. It refers to concepts discussed in the OpenGL
specification, and may be viewed as an X specific appendix to
that document. Parts of the document assume some
acquaintance with both the OpenGL and X.
In the X Window System, OpenGL rendering is made available as
an extension to X in the formal X sense: connection and
authentication are accomplished with the normal X mechanisms.
As with other X extensions, there is a defined network
protocol for the OpenGL rendering commands encapsulated
within the X byte stream.
Since performance is critical in 3D rendering, there is a
way for OpenGL rendering to bypass the data encoding step,
the data copying, and interpretation of that data by the X
server. This direct rendering is possible only when a
process has direct access to the graphics pipeline.
Allowing for parallel rendering has affected the design of
the GLX interface. This has resulted in an added burden on
the client to explicitly prevent parallel execution when
that is inappropriate.
X and the OpenGL have different conventions for naming entry
points and macros. The GLX extension adopts those of the
OpenGL.
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