xref: /third_party/openGLES/extensions/EXT/EXT_misc_attribute.txt

Name

    EXT_misc_attribute

Name Strings

    GL_EXT_misc_attribute

Version

    $Date: 1999/04/03 08:40:56 $ $Revision: 1.5 $

Number

    31

Dependencies

    None

Overview

    EXT_misc_attribute extends the list of attribute groups. It provides
    a miscellaneous group, controlled by the MISC_BIT_EXT bit, that contains
    the attribute state of extensions that don't logically fit in any other
    group. 

Reasoning

    In general, an extension's attributes are assigned to a similar
    attribute group. If an extension is developed that doesn't fit in
    any of the GL's existing attribute groups, the extension's attributes
    should be added to the miscellaneous group.
        
    The GL sample implementation incorrectly checks the bits in
    the <mask> argument to PushAttrib and glXCopyContext,
    generating an error if any unused bits are set. This
    behavior causes interoperability problems between GLs with
    different sets of attribute groups. This error checking
    should be removed from all implementations. The reference
    to this error checking should also be removed from the GLX
    specification.

    Because of the bit checking described above, ALL_ATTRIB_BITS
    can't include MISC_BIT_EXT without risking GL interoperability
    problems. Not including MISC_BIT_EXT changes the semantics of
    ALL_ATTRIB_BITS, but is considered the lesser of two evils.
    These problems should be fixed in the next GL version.

New Procedures and Functions

    None

New Tokens

    MISC_BIT_EXT

Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation)

    None

Additions to Chapter 3 of the 1.0 Specification (Rasterization)

    None

Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations
and the Frame Buffer)

    None

Additions to Chapter 5 of the 1.0 Specification (Special Functions)

    None

Additions to Chapter 6 of the 1.0 Specification (State and State Requests)

    The command

        void PushAttrib(bitfield mask)

    takes a bitwise OR of symbolic constants indicating which groups of
    state variables to push onto an attribute stack. Each constant refers
    to a group of state variables. The single symbolic constant
    GL_ALL_ATTRIB_BITS can be used to copy all of the attribute groups defined
    by the core GL. Additional extension attribute groups cannot be copied
    using GL_ALL_ATTRIB_BITS. To copy these groups, check to see that the GL
    implementation supports the extension, then use a bitwise OR to set
    the appropriate bit(s) in <mask>.


(Table 6.1 (Attribute Groups).)

    Attribute                   Constant                ALL_ATTRIB_BITS
    ---------                   --------                ---------------

    accum-buffer                ACCUM_BUFFER_BIT        yes
    color-buffer                COLOR_BUFFER_BIT        yes
    current                     CURRENT_BIT             yes
    depth-buffer                DEPTH_BUFFER_BIT        yes
    enable                      ENABLE_BIT              yes
    eval                        EVAL_BIT                yes
    fog                         FOG_BIT                 yes
    hint                        HINT_BIT                yes
    lighting                    LIGHTING_BIT            yes
    line                        LINE_BIT                yes
    list                        LIST_BIT                yes
    pixel                       PIXEL_MODE_BIT          yes
    point                       POINT_BIT               yes
    polygon                     POLYGON_BIT             yes
    polygon-stipple             POLYGON_STIPPLE_BIT     yes
    scissor                     SCISSOR_BIT             yes
    stencil-buffer              STENCIL_BUFFER_BIT      yes
    texture                     TEXTURE_BIT             yes
    transform                   TRANSFORM_BIT           yes
    viewport                    VIEWPORT_BIT            yes
    miscellaneous               MISC_BIT_EXT            no
    -                           ALL_ATTRIB_BITS         -


Additions to the GLX Specification

(In the glXCopyContext description)

    The single symbolic constant GL_ALL_ATTRIB_BITS can be used to
    copy all of the attribute groups defined by the core GL. Additional
    extension attribute groups can not be copied using GL_ALL_ATTRIB_BITS.
    To copy these groups, check to see that the GL implementation supports
    the extension, then use a bitwise OR to set the appropriate bit(s) in
    <mask>.

Errors

    None

New State

    None

New Implementation Dependent State

    None