Syntax Rules for OpenGL Extensions
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This is a preliminary document. No ARB vote has been taken!
Required abbreviations
----------------------
Accum Accumulation Buffer
Attrib Attribute
Aux Auxiliary
CCW Counter Clockwise
Clip Clipping
CMYK Cyan Magenta Yellow Black
Coeff Coefficient
Coord Coordinate
CW Clockwise
Decr Decrement
Dim Dimension
Dst Destination
Env Environment
Eval Evaluate
Exp Exponential
Func Function
Gequal Greater than or equal to
Gen Generate
Incr Increment
Index Color Index
Lequal Less than or equal to
Light Model Lighting Model
List Display List
LSB Least significant bit
Mag Magnify
Max Maximum
Min Minify
Mult Multiply
Op Operation
Ortho Orthographic
Pname ParameterName
Pos Position (function names only)
Quad Quadrilateral
Rect Rectangle
Ref Reference
RGB Red Green Blue
RGBA Red Green Blue Alpha
Shade Model Shading Model
Src Source
Tex Texture (function names only)
Abbreviations specifically not allowed
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Bgn Begin
C Color
Pnt Point
Cpack Color Pack
N Normal
Poly Polygon Poly means multiple
T Texture Coordinate
Tri Triangle
V Vertex
Compound words
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Antialias
Bitmap
Cutoff
Doublebuffer
Feedback
Framebuffer
Modelview
Noop
Notequal
Subpixel
Viewport
Writemask
Name rules (for all names)
--------------------------
Always use the specified abbreviations. Never abbreviate terms
that are already in the OpenGL API and are not abbreviated. If you
add terms to your extensions, abbreviate consistently, maintaining
a local versions of extensions to the list of abbreviations.
Use Depth, never Z.
Procedure name rules
--------------------
Limit procedure names to 2 words, 3 for procedures that return state.
(This is really a recommendation, not a rule.)
Never use set, as in SetFeedbackBuffer.
Begin each word with a capital letter, except the second word of
compound words.
Use Verb-noun (DeleteList) and adjective-noun (EdgeFlag) formats.
Append a corporate-specific suffix to all procedures. For example:
glNewCommandSGI. All upper case is preferred for this suffix, but
is not required. The suffix is always last, following OpenGL type
and count suffixes. (e.g. glNewVertex3iSGI, not glNewVertexSGI3i.)
Definition name rules
---------------------
Use all capital letters.
Separate words with underbars, except words within compound words.
Append simple numeric suffixes directly to the end of definition
tokens (LIGHT0). Begin these sequences with 0.
Use an underbar to separate complex suffixes from the token body
(MAP_3V).
Append a corporate-specific suffix to the token, after any other
suffixes. For example: GL_NEW_TOKEN0_SGI. All upper case is
required.
Parameter name rules
--------------------
<target> is reserved for the notion of "which is affected", and for
the corresponding "which is returned" get commands.
<params> is reserved for an array of parameters whose contents are
defined by a second enumerated argument, called <pname>.
Begin number sequences with 1, not 0. (e.g. u1,u2, not u0,u1)
Parameter order
---------------
<X> precedes <Y> precedes <Z> precedes <W>.
<R> precedes <G> precedes <B> precedes <A>.
The array being passed is always the last argument.
If a passed array has a type, the type specification argument immediately
precedes the array.
<pname> always precedes <params>.
<x> and <y> precede <width> and <height>
<format> precedes <type>
<target> is first
<face> is first
Parameter types
---------------
All integer quantity parameters (widths, heights, array lengths, etc.)
should be typed GLsizei, not GLint or GLuint. Note that GLsizei
generates an error only for negative values, so all integer quantity
parameters should accept the value zero.
Names (of display lists, textures, etc.) should be typed GLuint.
Generic masks that do not have explicitly defined bit values (e.g.
color index write masks and stencil write masks) should be typed
GLuint. GLuint is also used for unsigned integer components, such as
color components and depth components.
Masks that do have explicitly defined bit values (e.g. attribute mask,
clear mask) should be typed GLbitfield, not GLuint.
All floating point parameters that are clamped to the range [0,1] when
received should be typed GLclampf or GLclampd, not GLfloat or GLdouble.
Extension name rules
--------------------
An extension name is prefixed with the same string that suffixes its
procedures and definitions. The prefix and the individual words are
separated with underbars, the prefix is all upper case, and the other
text is all lower case. For example, extension SGI_cool_feature, which
specifies glCoolProcedureSGI() and defines GL_COOL_DEFINITION_SGI.
Suffix codes
------------
i signed 32-bit integer
ui unsigned 32-bit integer
s signed 16-bit integer
us unsigned 16-bit integer
b signed 8-bit integer
ub unsigned 8-bit integer
l signed 64-bit integer
ul unsigned 64-bit integer
f 32-bit float
d 64-bit float
v vector format
Shared extensions
-----------------
An OpenGL extension may be deemed a shared extension if either:
1. Two or more OpenGL licensees agree in good faith to implement
and ship the extension, or
2. The OpenGL ARB determines that it is in the best interest of
the licensees that the extension be shared.
The procedures and definitions that are defined by a shared extension
are suffixed with EXT, rather than by a company-specific suffix.
Likewise, the extension name is prefixed by EXT. To avoid name
conflicts Silicon Graphics will maintain a registry of EXT extensions,
including all their procedures and definitions, in a location that is
accessible to all licensees.