xref: /third_party/openGLES/extensions/SGIS/SGIS_multitexture.txt

Name

    SGIS_multitexture

Name Strings

    GL_SGIS_multitexture

Version

    $Date: 1998/10/15 00:54:19 $ $Revision: 1.20 $

Number

    116

Dependencies

    OpenGL 1.1 is required 
    EXT_texture3D affects the definition of this extension.
    SGIS_texture4D affects the definition of this extension.
    SGIS_texture_border_clamp affects the definition of this extension.
    SGI_texture_color_table affects the definition of this extension.
    SGIS_texture_edge_clamp affects the definition of this extension.
    SGIX_texture_add_env affects the definition of this extension.
    SGIS_texture_filter4 affects the definition of this extension.
    SGIS_texture_lod affects the definition of this extension.
    SGIX_texture_lod_bias affects the definition of this extension.
    SGIX_texture_scale_bias affects the definition of this extension.
    SGIS_texture_select affects the definition of this extension.
    SGIS_detail_texture affects the definition of this extension.
    SGIS_sharpen_texture affects the definition of this extension.
    SGIX_shadow affects the definition of this extension.
    SGIX_shadow_ambient affects the definition of this extension.
    SGIX_clipmap affects the definition of this extension.
    SGIS_point_line_texgen affects the definition of this extension.

Overview

    This extension adds support for multiple active textures.  The texture
    capabilities are symmetric for all active textures.  Any texture capability
    extension supported for one texture must be supported for all active
    textures.  Each active texture has its own state vector which includes
    texture image and filtering parameters and texture environment application.

    The texture environments are applied in a pipelined fashion whereby the
    output of one texture environment is used as the input fragment color for
    the texture environment for the next active texture.  Changes to texture
    state other than texture coordinates are routed through a selector which
    controls which instance of texture state is affected.

              +-----+
     Cf ----->|     |    +-----+                pipelined texture
              | TE0 |--->|     |                environment
    Ct0 ----->|     |    | TE1 |    +-----+
              +-----+    |     |--->|     |
    Ct1 ---------------->|     |    | TE2 |    +-----+
                         +-----+    |     |--->|     |
    Ct2 --------------------------->|     |    | TE3 |
                                    +-----+    |     |--> cf'
    Ct3 -------------------------------------->|     |
                                               +-----+
                .
                .
                .

        Ct<i> = texture color from texture lookup <i>
        Cf    = fragment color
        TE    = texture environment
    
    Texture coordinate set, texture coordinate evaluator state, texture
    generation function, and texture matrix are replicated independently of
    the texture rasterization state and may differ in number from the
    number of textures which can be active during rasterization.
    Post-transform texture coordinates sets are associated with a texture
    rasterization unit by binding them to a texture environment and they may
    be multicast to several texture rasterization units.

    The specification is written using four active textures and four
    sets of texture coordinates though the actual number supported is
    implementation dependent and can be larger or smaller than four.

Issues

    *  MultiTexCoord is an annoying name

    *  alternatives for supplying fine grain texcoord

        1. Tex<k>Coord<n><T>[v|f](<T> data);

           a. efficient, no error checking required
           d. adds *a lot* of new commands
        
        2. MultiTexCoord<n><T>[v|f](enum target, <T> data);

           a. only a small number of commands added
           a. can be fairly efficient (may need hw tweak)
           d. needs range checking for <target>
        
        3. reuse TexCoord command and add SelectTextureCoordSetSGIS(enum target)
           to control routing

           a. only add one new commands
           d. adds a lot of function call overhead when using multiple
              textures
           d. need to range check <target>

    *  seems a little hacky to have SelectTextureSGIS control texture matrix
       since that is part of transform state and to have it control evaluator
       state yet SELECTED_TEXTURE itself is part of texture state.

    *  SelectTextureSGIS probably should not affect client state such as
       the vertex array state.
        
        it doesn't any more

    *  mechanism to replicate input texcoords across multiple texture paths
       could be done with a pre-transform multicast or post-transform
       multicast.

        done using TEXTURE_ENV_COORD_SET_SGIS texture parameter
        which is a post-transform mechanism.

       RESOLVED: leave the coord source binding separate from
       the texture object state => needs a new command to set it.

    *  need proxy/macro object to handle resource constraints
        save for another extension?

    *  still need a way to route textures to lighting block :(

        defined in light_texture.spec

    *  should there be a post-filter colortable per texture?

    *  should the number of textures and the number of texture
       coordinate paths be decoupled?
        RESOLVED: yes
        There are some issues with this.  We choose to break
        texture state into 3 pieces:
            1. client state deal with issuing texture coordinates
               from the application
            2. transform state which includes texgen, texture
               matrix, evaluation maps, and texture coordinate
               retrieval from Gets and Feedback.
            3. rasterization state which includes texture
               images, filter parameters and environment.
        2 & 3 are both server state.  there is an implication
        that 1 and 2 are a little more tightly coupled and
        equal in number but we need to keep the client
        state separate.
        There is some clumsyness with referring to the 2nd
        group of state as transform state.  There is a problem
        that the texgen state is part of the texture state
        used in PushAttrib and PopAttrib so some finessing
        is required.

    *  special treatment of name 0?

        RESOLVED: no
    
    *  more texture environment functions, SUBTRACT, ...?
        leading candidates are SUBTRACT and REVERSE_SUBTRACT
        could also make a new version of environment which is
        similar to blending.

        RESOLVED: new environment, see texture_env.spec
    
    * more general combination of texture results?

        RESOLVED: do them in add-on specs
    
    * allow texture environment computation to do something
      even when texture is disabled. This contradicts the current
      specification of texturing (the difference would show
      up in the REPLACE environment), so we redefine this
      behavior in a new environment (see texture_env.spec)

    * support for interleaved arrays
      
      add a command which acts as a multiplier on the current
      interleaved array token causing the texture coordinate
      array to have <n> contiguous texture coords of the same
      type and format.

    * some clarifications:

      SelectTextureCoordSetSGIS affects client state only and
      affects the commands TexCoord<n>{T}[v], TexCoordPointer,
      EnableClientState, and DisableClientState.  Display lists
      contain texture coordinates for which the binding is fully
      resolved to one of TEXTURE0_SGIS ..  TEXTURE<n>_SGIS.

      I chose to remove MultiTexCoordPointerSGIS as it was difficult
      to also include tokens which would make it possible to call
      Enable/DisableClientState with a token corresponding to the
      appropriate texture coordinate set, so SelectTextureCoordSetSGIS
      is required to manipulate the array state.  To maintain symmetry,
      I made all commands use SelectTextureCoordSetSGIS and the
      MultiTexCoord<n>{T}[v]SGIS commands are added to help with
      performance.  An alternative would be to have both
      MultiTexCoordPointerSGIS and add new tokens
      TEXTURE_COORD_ARRAY0_SGIS .. TEXTURE_COORD_ARRAY<n>_SGIS and
      not give TEXTURE_COORD_ARRAY0_SGIS the same value as
      TEXTURE_COORD_ARRAY, so that we can have the relationship
      TEXTURE_COORD_ARRAY<i>_SGIS = TEXTURE_COORD_ARRAY0_SGIS+i.
      This still might cause some confusion/asymmetry if the <target>
      parameter of MultiTexCoordPointerSGIS/MultiTexCoord<n>{T}[v]SGIS
      is TEXTURE0_SGIS .. TEXTURE<n>_SGIS but EnableClientState/
      DisableClientState use TEXTURE_COORD_ARRAY0_SGIS ..
      TEXTURE_COORD_ARRAY<n>_SGIS

        

New Procedures and Functions

    void MultiTexCoord{1234}{sifd}SGIS(enum target, T coords);
    void MultiTexCoord{1234}{sifd}vSGIS(enum target, T coords);

    void InterleavedTextureCoordSetsSGIS(int factor);

    void SelectTextureSGIS(enum target);

    void SelectTextureCoordSetSGIS(enum target);

    void SelectTextureTransformSGIS(enum target);

New Tokens

    Accepted by the <pname> parameters of GetBooleanv, GetIntegerv,
    GetFloatv, and GetDoublev:

    SELECTED_TEXTURE_SGIS                       0x83C0
    SELECTED_TEXTURE_COORD_SET_SGIS             0x83C1
    SELECTED_TEXTURE_TRANSFORM_SGIS             0x83C2
    MAX_TEXTURES_SGIS                           0x83C3
    MAX_TEXTURE_COORD_SETS_SGIS                 0x83C4
    TEXTURE_COORD_SET_INTERLEAVE_FACTOR_SGIS    0x83C5

    Accepted by the <pname> parameter of TexEnvi, TexEnvf,
    TexEnviv, TexEnvfv, GetTexEnviv, and GetTexEnvfv:

    TEXTURE_ENV_COORD_SET_SGIS                  0x83C6

    Accepted by the <target> parameter of SelectTextureSGIS,
    SelectTextureTransformSGIS, SelectTextureCoordSetSGIS,
    MultiTexCoord<n>{T}[v]SGIS, and the <param> of TexParameteri and
    TexParameterf, and the <params> parameter of TexParameteriv, and
    TexParameterfv:

    TEXTURE0_SGIS                               0x83C7
    TEXTURE1_SGIS                               0x83C8
    TEXTURE2_SGIS                               0x83C9
    TEXTURE3_SGIS                               0x83CA
    <reserve enums for 32>

Additions to Chapter 2 of the 1.1 Specification (OpenGL Operation)

    Section 2.6 Begin/End Paradigm

    <amend paragraph 2 & 3>

    Each vertex is specified with two, three, or four coordinates.  In
    addition, a current normal, current texture coordinate set, and current
    color may be used in processing each vertex.  Normals are used by the GL in
    lighting calculations; the current normal is a three-dimensional vector
    that may be set by sending three coordinates that specify it.  Texture
    coordinates determine how a texture image is mapped onto a primitive.
    Multiple sets of texture coordinates may be used to specify how multiple
    texture images are mapped onto a primitive.  The number of texture
    coordinate sets supported is implementation dependent but must be at least
    one.

    A color is associated with each vertex as it is specified. This associated
    color is either the current color or a color produced by lighting
    depending on whether or not lighting is enabled. Texture coordinates are
    similarly associated with each vertex.  Multiple sets of texture coordinates
    may be associated with a vertex.  Figure 2.2 summarizes the association of
    auxiliary data with a transformed vertex to produce a processed vertex.

    <amend figure 2.2 to include multiple texcoord processing blocks
     (current texcoords, texgen, texture matrix)>

    <amend paragraph 6>
    Before a color has been assigned to a vertex, the state required by a vertex
    is the vertex's coordinates, the current normal, and the current texture
    coordinate sets.  Once color has been assigned, however, the current normal
    is no longer needed. Because color assignment is done vertex-by-vertex, a
    processed vertex comprises the vertex's coordinates, its assigned color,
    and its texture coordinate sets.



    Section 2.7 Vertex Specifications <texture coordinates>

    <amend paragraph 2>

    Current values are used in associating auxiliary data with a vertex
    as described in section 2.6.  A current value may be changed at any time
    by issuing an appropriate command.  The commands

    void TexCoord{1234}{sifd}(T coords);
    void TexCoord{1234}{sifd}v(T coords);

    specify the current homogeneous texture coordinates, named s,t,r, and q.
    The TexCoord1 family of commands set the s coordinate to the provided
    single argument while setting t and r to 0 and q to 1.  Similarly,
    TexCoord2 sets s and t to the specified values, r to 0, and q to 1;
    TexCoord3 sets s, t, and r, with q set to 1, and TexCoord4 sets all four
    texture coordinates.

    Implementations may support more than 1 set of texture
    coordinates.  The MultiTexCoord family of commands takes the
    coordinate set to be modified as the <target> parameter.  The
    <target> parameter is one of TEXTURE0_SGIS through
    TEXTURE3_SGIS. If a <target> parameter greater than the number of
    supported coordinate sets is specified, the command has no effect.
    The command

    void SelectTextureCoordSetSGIS(enum target);

    is used to change the texture coordinate set modified by the TexCoord*
    family of commands.  <target> is one of TEXTURE0_SGIS through TEXTURE3_SGIS
    corresponding to the texture coordinate set to be modified by the TexCoord
    commands.  The current coordinate set selection is part of client state rather
    than server state.


    Section 2.8 Vertex Arrays

    <amend paragraph 1>

    The vertex specification commands in section 2.7 accept data in almost any
    format, but their use requires many command executions to specify even
    simple geometry.  Vertex data may also be placed in arrays that are stored
    in the client's address space. Blocks of data in these arrays may be used
    to specify multiple geometric primitives through the execution of a single
    GL command.  The client may specify 6 or more arrays at once: one each to
    store vertex coordinates, edge flags, colors, color indices, normals and
    one or more texture coordinate sets. The commands

    void EdgeFlagPointer(sizei stride, void *pointer);
    void VertexPointer(int size, enum type, sizei stride, void *pointer);
    void ColorPointer(int size, enum type, sizei stride, void *pointer);
    void IndexPointer(enum type, sizei stride, void *pointer);
    void NormalPointer(enum type, sizei stride, void *pointer);
    void TexCoordPointer(int size, enum type, sizei stride, void *pointer);

    ...

    <insert this paragraph> between paragraph 2 & 3>

    In implementations which support more than one set of texture coordinates,
    the command SelectTextureCoordSetSGIS is used to select the vertex array
    parameters to be modified by the TexCoordPointer command and the array
    affected by client state enable and disable commands with the
    TEXTURE_COORD_ARRAY parameter.

    <modify the section on interleaved arrays as follows>

        The commands

        void InterleavedArrays(enum format, sizei stride,
            void *pointer) ;
        
        void InterleavedTextureCoordSetsSGIS(int factor) ;
    
    efficiently initializes the six arrays and their enables to one of 14
    configurations. <format> must be one 14 symbolic constants: V2F, V3F,
    C4UB_V2F, C4UB_V3F, C3F_V3F, N3F_V3F, C4F_N3F_V3F, T2F_V3F, T4F_V4F,
    T2F_C4UB_V3F, T2F_C3F_V3F, T2F_N3F_V3F, T2F_C4F_N3F_V3F, T4F_C4F_N3F_V4F.
    <factor> is an integer between 1 and SELECTED_TEXTURE_COORD_SET_SGIS
    and specifies how many texture coordinate sets are enabled as part
    of the InterleavedArrays command.

        The effect of

            InterleavedArrays(format, stride, pointer);
            InterleavedTextureCoordSetsSGIS(factor);

    is the same as the effect of the command sequence

           <copy command sequence from 1.1 spec, but change the part dealing
            with texture coords to>

            GetIntegerv(SELECTED_TEXTURE_COORD_SET_SGIS, &x);
            if (<et>) {
                for(i = 0; i < factor; i++) {
                    SelectTextureCoordSetSGIS(TEXTURE0_SGIS+i);
                    EnableClientState(TEXTURE_COORD_ARRAY);
                    TexCoordPointer(st, FLOAT, str, <pointer>+i*pc);
                }
                for(i = factor; i < MAX_TEXTURE_COORD_SETS_SGIS; i++) {
                    SelectTextureCoordSetSGIS(TEXTURE0_SGIS+i);
                    DisableClientState(TEXTURE_COORD_ARRAY);
                }
            } else {
                for(i = 0; i < MAX_TEXTURE_COORD_SETS_SGIS; i++) {
                    SelectTextureCoordSetSGIS(TEXTURE0_SGIS+i);
                    DisableClientState(TEXTURE_COORD_ARRAY);
                }
            }
            SelectTextureCoordSetSGIS(x);
            pc *= factor;
    

    If the number of supported is texture coordinate sets,
    MAX_TEXTURE_COORD_SETS_SGIS, is <k>, then the client state require to
    implement vertex arrays consists of five plus <k> boolean values, five
    plus <k> integer stride values, four plus <k> constants representing array
    types, and three plus <k> integers representing values per element.  In the
    initial state, the boolean values are each disabled, the memory pointers
    are each null, the strides are each zero, the array types are each FLOAT,
    and the integers representing values per element are each four.


    Section 2.10.2 Matrices
    
    <amend paragraph 8 texture matrix>

    There is another 4x4 matrix that is applied to texture coordinates.
    This matrix is applied as

                | m1 m5 m9  m13 | |s|
                | m2 m6 m10 m14 | |t| ,
                | m3 m7 m11 m15 | |r|
                | m4 m8 m12 m16 | |q|

    where the left matrix is the current texture matrix.  The Matrix is applied
    to the coordinates resulting from texture coordinate generation which
    (which may simply be the current texture coordinates), and the resulting
    transformed coordinates become the texture coordinates associated with a
    vertex.  Setting the matrix mode to TEXTURE causes the already described
    matrix operations to apply to the texture matrix stack.

    For implementations which support more than one set of texture coordinates,
    there is a corresponding texture matrix stack for each coordinate set. Each
    stack has the same depth. The texture matrix stack which is affected by the
    matrix operations is set using the SelectTextureTransformSGIS command.

    There is a stack of matrices for each of the matrix modes.  For MODELVIEW
    mode, the stack depth is at least 32 (that is, there is a stack of at least
    32 model-view matrices). For other modes, the depth is at least 2.  Texture
    matrix stacks for all texture coordinate sets have the same depth.

        void PushMatrix( void );

    pushes the stack down by one, duplicating the current matrix in both the
    top of the stack and the entry below it.

        void PopMatrix( void );
    
    pops the top entry off of the stack, replacing the current matrix with the
    matrix that was the second entry in the stack.  The pushing or popping
    takes place on the stack corresponding to the current matrix mode.  Popping
    a matrix off a stack with only one entry generates the error STACK_UNDERFLOW;
    pushing a matrix onto a full stack generates STACK_OVERFLOW.

    When the current matrix mode is TEXTURE, the texture matrix stack corresponding
    to the currently selected textured is pushed or popped.

    The state required to implement transformations consists of a three-value
    integer indicating the current matrix mode, a stack of at least two 4x4
    matrices for PROJECTION and one stack of at least two 4x4 matrices for
    each set of texture coordinates, TEXTURE, as well as associated stack pointers,
    and a stack of at least 32 4x4 matrices with an associated stack pointer for
    MODELVIEW.  Initially, there is only one matrix on each stack and all
    matrices are set to the identity.  The initial matrix mode is MODELVIEW.

    Section 2.10.4 Generating texture coordinates

    <amend paragraph 4>

    The state required for texture coordinate generation for each set of
    texture coordinates supported by the implementation comprises a
    three-valued integer for each coordinate indicating coordinate generation
    mode, and a bit for each coordinate to indicate whether texture coordinate
    generation is enabled or disabled.  In addition, four coefficients are
    required for the four coordinates for each of EYE_LINEAR and
    OBJECT_LINEAR.  The initial state has the texture generation function
    disabled for all texture coordinates.  The initial values of p_i for s
    except p_1 which is one; for t all the p_i are zero except p_2, which is
    1.  The values of p_i for r and q are all zero.  These values of p_i apply
    for both the EYE_LINEAR and OBJECT_LINEAR versions.  Initially all texture
    generation modes are EYE_LINEAR.

    Section 2.12  Current Raster Position

    <amend paragraph 2>

    The current raster position consists of three window coordinates x_w,
    y_w, and z_w, a clip coordinate w_c value, and eye coordinate distance,
    a valid bit, and associated data consisting op a color and texture
    coordinate sets.  It is set using one of the RasterPos commands:
    ...

    <amend paragraph 5>

    The current raster position requires five single-precision floating-point
    values for its x_w, y_w, and z_w window coordinates, its w_c clip
    coordinate, and its eye coordinate distance, a single valid bit, a color
    (RGBA and color index), and texture coordinates for each set of texture
    coordinates supported by the implementation.  In the initial state, the
    coordinates and texture coordinates and both (0,0,0,1), the eye coordinate
    distance is 0, the valid bit is set, the associated RGBA color is (1,1,1,1)
    and the associated color index is 1. In RGBA mode, the associated color
    index always has its initial value; in color index mode, the RGBA color
    always maintains its initial value.


Additions to Chapter 3 of the 1.1 Specification (Rasterization)

    Section 3.8 Texturing

    <amend paragraphs 1 & 2>

    Texturing maps a portion of one or more specified images onto each
    primitive for which texturing is enabled.  This mapping is accomplished by
    using the color of an image at the location indicated by a fragment's
    (s,t,r) coordinates to modify the fragment's RGBA color (r is currently
    ignored).  An implementation may support texturing using more than one
    image at a time.  In this case the fragment carries multiple sets of
    texture coordinates (s,t,r) which are used to index separate images to
    produce color values which are collectively used to modify the fragment's
    RGBA color.  Texturing is specified only for RGBA mode; its use in color
    index mode is undefined.  The following subsections (up to and including
    Section 3.8.5) specify the GL operation with a single texture and Section
    3.8.6 specifies the details of how multiple textures interact.

    The GL provides a means to specify the details of how texturing of a
    primitive is effected. These details include specifications of the image to
    be texture mapped, the means by which the image is filtered when applied to
    the primitive, and the function that determines what RGBA value is produced
    given a fragment color and an image value.


    Section 3.8.4 Texture Objects

    <add this paragraph to the end of the section>

    The texture object name space is shared amongst all textures in multiple
    texture implementations.   A texture object may be bound to more than one
    texture target simultaneously, though they must all be of the same type
    (e.g., TEXTURE_1D, TEXTURE_2D).  After a texture object is bound, any GL
    operations on that target also affect any other target to which the same
    texture object is bound.


    Section 3.8.5 Texture Environments and Texture Functions

    <amend the second half of paragraph 1>
    The possible environment parameters are TEXTURE_ENV_MODE,
    TEXTURE_ENV_COLOR, and TEXTURE_ENV_COORD_SET_SGIS.  TEXTURE_ENV_MODE may be
    set to one of REPLACE, MODULATE, DECAL, or BLEND; TEXTURE_ENV_COLOR is set
    to an RGBA color by providing four single-precision floating-point values
    in the range [0,1](values outside this range are clamped to it).  If
    integers are provided for TEXTURE_ENV_COLOR, then they are converted to
    floating-point as specified in Table 2.6 for signed integers.
    TEXTURE_ENV_COORD_SET_SGIS may be set to one of TEXTURE0_SGIS ..
    TEXTURE<n>_SGIS where <n> is one less than the number of supported
    texture coordinate sets.  If a floating-point value is provided, then it
    is rounded to the nearest integer.

    <insert before paragraph 3>

    The value of TEXTURE_ENV_COORD_SET_SGIS specifies which set of fragment
    texture coordinates are used to determine the texture value used in
    the texture function.  The same set of texture coordinates may
    be simultaneously used by multiple textures.

    <replace paragraph 3>

    The state required for the current texture environment consists of the
    four-valued integer indicating the texture function, four floating-
    point TEXTURE_ENV_COLOR values, and one MAX_TEXTURE_COORD_SETS_SGIS-valued
    integer indicating the texture coordinate set binding. In the initial
    state, the texture function is given by MODULATE, TEXTURE_ENV_COLOR is
    (0,0,0,0), and texture coordinate set is TEXTURE0_SGIS.


    Section 3.8.6 Texture Application <replace with this>

    Texturing is enabled or disabled using the generic Enable and Disable
    commands, respectively, with the symbolic constant TEXTURE_1D or TEXTURE_2D
    to enable the one-dimensional or two-dimensional texture, respectively.  If
    both the one- and two-dimensional textures are enabled, the two-dimensional
    texture is used.  If all texturing is disabled, a rasterized fragment is
    passed unaltered to the next stage of the GL (although its texture
    coordinates may be discarded).  Otherwise, a texture value is found
    according to the parameter values of the currently bound texture image of
    the appropriate dimensionality using the rules given in sections 3.8.1 and
    3.8.2.  This texture value is used along with the incoming fragment in
    computing the texture function indicated by the currently bound texture
    environment.  The result of this function replaces the incoming fragment's
    R, G, B, and A values.  These are the color values passed to subsequent
    operations.  Other data associated with the incoming fragment remain
    unchanged, except that the texture coordinates may be discarded.

    When multiple textures are supported, additional textures are each paired
    with an environment function.  The second texture function is computed
    using the texture value from the second texture, the fragment resulting
    from the first texture function computation and the environment function
    currently bound to the second texture.  If there is a third texture, the
    fragment resulting from the second texture function is combined with the
    third texture value using the environment function bound to the third
    texture and so on.  Texturing is enabled and disabled individually for each
    texture.  If texturing is disabled for one of the textures, then the
    fragment result from the previous stage is passed unaltered to the next
    stage.


Additions to Chapter 4 of the 1.1 Specification (Per-Fragment Operations
and the Framebuffer)


Additions to Chapter 5 of the 1.1 Specification (Special Functions)

    Section 5.1 Evaluators

    <amend second part of paragraph 2 to indicate that the evaluator
    map modified is affected by SELECTED_TEXTURE_TRANSFORM_SGIS when the
    the type parameter is one of the texture coordinates.>

    <amend paragraph 7>

    The evaluation of a defined map is enabled or disabled with Enable and
    Disable using the constant corresponding to the map as described
    above.  In implementations which support multiple texture coordinates the
    affected texture evaluator map is further qualified by the value of
    SELECTED_TEXTURE_TRANSFORM_SGIS.  The error INVALID_VALUE results if
    either ustride or vstride is less than k, or if u1 is equal to u2, or
    if v1 is equal to v2.


    Section 5.3 Feedback

    <amend bottom of paragraph 2>

    The texture coordinates and colors returned are these resulting from the
    clipping operations described in (section 2.13.8).  Only one set of texture
    coordinates is returned even for implementations which support multiple
    texture coordinates.  The texture coordinate set returned is the the one
    corresponding to the value of SELECTED_TEXTURE_TRANSFORM_SGIS.


Additions to Chapter 6 of the 1.1 Specification (State and State Requests)

    <add this paragraph after paragraph 14 regarding multi-valued state variables>

    When multiple textures are supported, most texture state variables are
    further qualified by the value of SELECTED_TEXTURE_TRANSFORM_SGIS or
    SELECTED_TEXTURE_SGIS to determine which server texture state vector is
    queried.  Client texture state variables such as texture coordinate
    array pointers are qualified with SELECTED_TEXTURE_COORD_SET_SGIS.
    Tables 6.5 through 6.22 indicate those state variables which are
    qualified by SELECTED_TEXTURE_TRANSFORM_SGIS, SELECTED_TEXTURE_SGIS or
    SELECTED_TEXTURE_COORD_SET_SGIS during state queries.

    <add this paragraph after paragraph 16 regarding the TEXTURE_BIT>

    When multiple textures are supported, operations on groups containing
    replicated texture state push or pop all versions of texture state
    within that group.  When server state for a group is pushed all state
    in the group corresponding to TEXTURE0_SGIS is pushed first, followed by
    state corresponding to TEXTURE1_SGIS, and so on up to and including the
    state corresponding to TEXTURE<n>_SGIS where <n> is the value of
    max{MAX_TEXTURES_SGIS, MAX_TEXTURE_COORD_SETS_SGIS}.  If state does
    not exist for an attribute (this can occur when MAX_TEXTURES_SGIS is
    not equal to MAX_TEXTURE_COORD_SETS_SGIS) then it is ignored.
    When server state for a group is popped the replicated texture state is
    restored in the opposite order that it was pushed, starting with state
    corresponding to TEXTURE<n>_SGIS and ending with TEXTURE0_SGIS.
    Identical rules are observed for client texture state push and pop
    operations.

    <rename vertex_array attribute group to vertex>


Additions to the GLX Specification

    None
    
GLX Protocol

    TBD

Dependencies on EXT_texture3D

    If EXT_texture3D is not supported than the functionality and state
    associated with EXT_texture3D does not exist and is therefore not
    extended.

Dependencies on SGIS_texture4D

    If SGIS_texture4D is not supported than the functionality and state
    associated with SGIS_texture4D does not exist and is therefore not
    extended.

Dependencies on SGIS_texture_border_clamp

    If SGIS_texture_border_clamp is not supported than the functionality and
    state associated with SGIS_texture_border_clamp does not exist and is
    therefore not extended.

Dependencies on SGI_texture_color_table

    If SGI_texture_color_table is not supported than the functionality and
    state associated with SGI_texture_color_table does not exist and is
    therefore not extended.

Dependencies on SGIS_texture_edge_clamp

    If SGIS_texture_edge_clamp is not supported than the functionality and
    state associated with SGIS_texture_edge_clamp does not exist and is
    therefore not extended.

Dependencies on SGIX_texture_add_env

    If SGIX_texture_add_env is not supported than the functionality and
    state associated with SGIX_texture_add_env does not exist and is
    therefore not extended.

Dependencies on SGIS_texture_filter4

    If SGIS_texture_filter4 is not supported than the functionality and
    state associated with SGIS_texture_filter4 does not exist and is
    therefore not extended.

Dependencies on SGIS_texture_lod

    If SGIS_texture_lod is not supported than the functionality and state
    associated with SGIS_texture_lod does not exist and is therefore not
    extended.

Dependencies on SGIX_texture_lod_bias

    If SGIX_texture_lod_bias is not supported than the functionality and
    state associated with SGIX_texture_lod_bias does not exist and is
    therefore not extended.

Dependencies on SGIX_texture_scale_bias

    If SGIX_texture_scale_bias is not supported than the functionality and
    state associated with SGIX_texture_scale_bias does not exist and is
    therefore not extended.

Dependencies on SGIS_texture_select

    If SGIS_texture_select is not supported than the functionality and state
    associated with SGIS_texture_select does not exist and is therefore not
    extended.

Dependencies on SGIS_detail_texture

    If SGIS_detail_texture is not supported than the functionality and state
    associated with SGIS_detail_texture does not exist and is therefore not
    extended.

Dependencies on SGIS_sharpen_texture

    If SGIS_sharpen_texture is not supported than the functionality and
    state associated with SGIS_sharpen_texture does not exist and is
    therefore not extended.

Dependencies on SGIX_shadow

    If SGIX_shadow is not supported than the functionality and state
    associated with SGIX_shadow does not exist and is therefore not
    extended.

Dependencies on SGIX_shadow_ambient

    If SGIX_shadow_ambient is not supported than the functionality and state
    associated with SGIX_shadow_ambient does not exist and is therefore not
    extended.

Dependencies on SGIX_clipmap

    If SGIX_clipmap is not supported than the functionality and state
    associated with SGIX_clipmap does not exist and is therefore not
    extended.

Dependencies on SGIS_point_line_texgen

    If SGIS_point_line_texgen is not supported than the functionality and
    state associated with SGIS_point_line_texgen does not exist and is
    therefore not extended.


Errors

    INVALID_ENUM is generated if SelectTextureSGIS,
    SelectTextureTransformSGIS, SelectTextureCoordSetSGIS,
    MultiTexCoord<n>{T}[v]SGIS, or MultiTexCoordPointer parameter <target> is
    not TEXTURE0_SGIS .. TEXTURE3_SGIS.

    INVALID_OPERATION is generated if SelectTextureCoordSetSGIS or
    SelectTextureTransformSGIS parameter <target> is one of TEXTURE0_SGIS
    .. TEXTURE3_SGIS and <target> is greater or equal than the number of
    available textures coordinate sets.

    INVALID_VALUE is generated if InterleavedTextureCoordSetsSGIS parameter
    <factor> is not between 1 and MAX_TEXTURE_COORD_SETS_SGIS.

    INVALID_OPERATION is generated if SelectTextureSGIS parameter <target> is
    one of TEXTURE0_SGIS .. TEXTURE3_SGIS and <target> is greater or equal than
    the number of available textures.

    INVALID_ENUM is generated if TexEnv{T}[v] parameter <pname> is
    TEXTURE_ENV_COORD_SET_SGIS and the <param> parameter is not one of
    TEXTURE0_SGIS .. TEXTURE3_SGIS.

    INVALID_OPERATION is generated if TexEnv{T}[v] parameter <pname>
    is TEXTURE_ENV_COORD_SET_SGIS and the <param> parameter is greater or equal
    than the number of available textures coordinate sets.

    INVALID_OPERATION is generated if SelectTextureSGIS or
    SelectTextureTransformSGIS is executed between execution of Begin and the
    corresponding execution of End.

    INVALID_OPERATION is generated if SelectTextureCoordSetSGIS or
    MultiTexCoordPointerSGIS  is executed between execution of Begin and the
    corresponding execution of End, but some implementations may not generate
    the error.  In such cases the result of executing these commands is
    undefined.

New State

    Get Value                           Get Command             Type            Initial Value           Attribute
    ---------                           -----------             ----            -------------           ---------
    SELECTED_TEXTURE_SGIS               GetIntegerv             Z4              TEXTURE0_SGIS           texture
    SELECTED_TEXTURE_TRANSFORM_SGIS     GetIntegerv             Z4              TEXTURE0_SGIS           texture
    SELECTED_TEXTURE_COORD_SET_SGIS     GetIntegerv             Z4              TEXTURE0_SGIS           vertex
    TEXTURE_COORD_SET_INTERLEAVE_FACTOR_SGIS    GetIntegerv     Z4              1                       vertex

Replicated State

    Get Value                           Get Command             Type            Initial Value           Attribute
    ---------                           -----------             ----            -------------           ---------
  x CURRENT_TEXTURE_COORDS              GetFloatv               1* x T          (0,0,0,1)               current
  x CURRENT_RASTER_TEXTURE_COORDS       GetFloatv               1* x T          (0,0,0,1)               current

  c TEXTURE_COORD_ARRAY                 IsEnabled               1* x B          False                   vertex-array
  c TEXTURE_COORD_ARRAY_SIZE            GetIntegerv             1* x Z+         0                       vertex-array
  c TEXTURE_COORD_ARRAY_TYPE            GetIntegerv             1* x Z4         FLOAT                   vertex-array
  c TEXTURE_COORD_ARRAY_STRIDE          GetIntegerv             1* x Z+         0                       vertex-array
  c TEXTURE_COORD_ARRAY_POINTER         GetPointerv             1* x Y          0                       vertex-array

  x TEXTURE_MATRIX                      GetFloatv               1* x 2* x M4    Identity                -
  x TEXTURE_STACK_DEPTH                 GetIntegerv             1* x Z+         1                       -

    TEXTURE_1D                          IsEnabled               1* x B          False                   texture/enable
    TEXTURE_2D                          IsEnabled               1* x B          False                   texture/enable
    TEXTURE_3D_EXT                      IsEnabled               1* x B          False                   texture/enable
    TEXTURE_4D_SGIS                     IsEnabled               1* x B          False                   texture/enable
    TEXTURE_BINDING_1D                  GetIntegerv             1* x Z+         0                       texture
    TEXTURE_BINDING_2D                  GetIntegerv             1* x Z+         0                       texture
    TEXTURE_BINDING_3D_EXT              GetIntegerv             1* x Z+         0                       texture
    TEXTURE_BINDING_4D_SGIS             GetIntegerv             1* x Z+         0                       texture
    TEXTURE                             GetTexImage             1* x n x I      see sec 3.8             -
    TEXTURE_WIDTH                       GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_HEIGHT                      GetTexLevelParameter    1* x n x Z+     0                       -
   +TEXTURE_DEPTH_EXT                   GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_BORDER                      GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_INTERNAL_FORMAT             GetTexLevelParameter    1* x n x Z+     0                       -
    (TEXTURE_COMPONENTS)
    TEXTURE_RED_SIZE                    GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_GREEN_SIZE                  GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_BLUE_SIZE                   GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_ALPHA_SIZE                  GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_LUMINANCE_SIZE              GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_INTENISTY_SIZE              GetTexLevelParameter    1* x n x Z+     0                       -
    TEXTURE_BORDER_COLOR                GetTexParameter         1* x 2+ x C     (0,0,0,0)               texture
    TEXTURE_MIN_FILTER                  GetTexParameter         1* x 2+ x Z6    see sec 3.8             texture
    TEXTURE_MAG_FILTER                  GetTexParameter         1* x 2+ x Z2    see sec 3.8             texture
    TEXTURE_WRAP_S                      GetTexParameter         1* x 2+ x Z2    REPEAT                  texture
    TEXTURE_WRAP_T                      GetTexParameter         1* x 2+ x Z2    REPEAT                  texture
   +TEXTURE_WRAP_R_EXT                  GetTexParameter         1* x 2+ x Z2    REPEAT                  texture
   +TEXTURE_WRAP_Q_SGIS                 GetTexParameter         1* x 2+ x Z2    REPEAT                  texture
    TEXTURE_PRIORITY                    GetTexParameterfv       1* x 2+ x R[0,1]        1               texture
    TEXTURE_RESIDENT                    GetTexParameterfv       1* x 2+ x B     False                   texture

   +TEXTURE_MIN_LOD_SGIS                GetTexParameterfv       1* x n x R      -1000                   texture
   +TEXTURE_MAX_LOD_SGIS                GetTexParameterfv       1* x n x R      1000                    texture
   +TEXTURE_BASE_LEVEL_SGIS             GetTexParameteriv       1* x n x R      0                       texture
   +TEXTURE_MAX_LEVEL_SGIS              GetTexParameteriv       1* x n x R      1000                    texture

   +TEXTURE_LOD_BIAS_S_SGIX             GetTexParameterfv       1* x n x R      0                       texture
   +TEXTURE_LOD_BIAS_T_SGIX             GetTexParameterfv       1* x n x R      0                       texture
   +TEXTURE_LOD_BIAS_R_SGIX             GetTexParameterfv       1* x n x R      0                       texture

   +TEXTURE_FILTER4_FUNC_SGIS           GetTexFilterFuncSGIS    1* x 2 x Size x R       see text        texture

   +DETAIL_TEXTURE_2D_BINDING_SGIS      GetIntegerv             1* x Z+         0                       texture
   +DETAIL_TEXTURE_LEVEL_SGIS           GetTexParameteriv       1* x n x Z-     -4                      texture
   +DETAIL_TEXTURE_MODE_SGIS            GetTexParameteriv       1* x n x Z2     ADD                     texture
   +DETAIL_TEXTURE_FUNC_POINTS_SGIS     GetTexParameteriv       1* x n x Z+     2                       texture
   +<DETAIL_TEXTURE_FUNC>               GetDetailTexFuncSGIS    1* x n x m x R  {0, 0}, {-4, 1}         texture

   +SHARPEN_TEXTURE_FUNC_POINTS_SGIS    GetTexParameteriv       1* x n x Z+     2                       texture
   +<SHARPEN_TEXTURE_FUNC>              GetSharpenTexFuncSGIS   1* x n x m x R  {0, 0}, {-4, 1}         texture

   +TEXTURE_COMPARE_SGIX                GetTexParameter[if]v    1* x B          False                   texture
   +TEXTURE_COMPARE_OPERATOR_SGIX       GetTexParameter[if]v    1* x Z_2        TEXTURE_LEQUAL_R_SGIX   texture

   +SHADOW_AMBIENT_SGIX                 GetTexParameter[if]v    1* x R[0,1]     0.0                     texture

   +TEXTURE_CLIPMAP_FRAME_SGIX          GetTexParameterf        1* x Z+         0                       texture
   +TEXTURE_CLIPMAP_CENTER_SGIX         GetTexParameterfv       1* x 2 x Z+     0,0                     texture
   +TEXTURE_CLIPMAP_OFFSET_SGIX         GetTexParameterfv       1* x 2 x Z+     0,0                     texture
   +TEXTURE_CLIPMAP_VIRTUAL_DEPTH_SGIX  GetTexParameterfv       1* x 3 x Z+     0,0,0                   texture

   +DUAL_TEXTURE_SELECT_SGIS            GetTexParameter         1* x n x 3 x Z2 0                       texture
   +QUAD_TEXTURE_SELECT_SGIS            GetTexParameter         1* x n x 3 x Z4 0                       texture

   +POST_TEXTURE_FILTER_BIAS_SGIX       GetTexParameterfv       1* x n x 4 x R  (0,0,0,0)               texture
   +POST_TEXTURE_FILTER_SCALE_SGIX      GetTexParameterfv       1* x n x 4 x R  (1,1,1,1)               texture

    TEXTURE_COLOR_TABLE_SGI             IsEnabled                       B               False           texture/enable
   +COLOR_TABLE                         GetColorTableSGI                4 x I           empty           -
   +COLOR_TABLE_FORMAT_SGI              GetColorTableParameterivSGI     2 x 4 x Z38     RGBA            -
   +COLOR_TABLE_WIDTH_SGI               GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_RED_SIZE_SGI            GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_GREEN_SIZE_SGI          GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_BLUE_SIZE_SGI           GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_ALPHA_SIZE_SGI          GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_LUMINANCE_SIZE_SGI      GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_INTENSITY_SIZE_SGI      GetColorTableParameterivSGI     2 x 4 x Z+      0               -
   +COLOR_TABLE_SCALE_SGI               GetColorTableParameterfvSGI     4 x R4          (1,1,1,1)       pixel
   +COLOR_TABLE_BIAS_SGI                GetColorTableParameterfvSGI     4 x R4          (0,0,0,0)       pixel

    TEXTURE_ENV_MODE                    GetTexEnviv             1* x Z4         MODULATE                texture
    TEXTURE_ENV_COLOR                   GetTexEnviv             1* x C          (0,0,0,0)               texture
    TEXTURE_ENV_COORD_SET_SGIS          GetTexEnviv             1* x Z4         see sec 3.8             texture
  x TEXTURE_GEN_x                       IsEnabled               1* x 4 x B      False                   texture/enable
  x EYE_PLANE                           GetTexGenfv             1* x 4 x R4     see sec 2.10.4          texture
  x OBJECT_PLANE                        GetTexGenfv             1* x 4 x R4     see sec 2.10.4          texture
  x TEXTURE_GEN_MODE                    GetTexGeniv             1* x 4 x Z3     EYE_LINEAR              texture

   +TEXTURE_ENV_BIAS_SGIX               GetFloatv               1* x C          (0,0,0,0)               texture

  x+EYE_POINT_SGIS                      GetTexGeniv             1* x 4 x R      (0,0,0,1)               texture
  x+OBJECT_POINT_SGIS                   GetTexGeniv             1* x 4 x R      (0,0,0,1)               texture
  x+EYE_LINE_SGIS                       GetTexGeniv             1* x 7 x R      (0,0,0,1,0,0,1)         texture
  x+OBJECT_LINE_SGIS                    GetTexGeniv             1* x 7 x R      (0,0,0,1,0,0,1)         texture

  x ORDER                               GetMapiv                (k+9) x Z8*     1                       -
  x ORDER                               GetMapiv                (k+9) x 2 x Z8* 1,1                     -
  x COEFF                               GetMapfv                (k+9) x 8* x Rn see sec 5.1             -
  x COEFF                               GetMapfv                (k+9) x 8* x 8* x Rn    see sec 5.1             -
  x DOMAIN                              GetMapfv                (k+9) x 2 x R   see sec 5.1             -
  x DOMAIN                              GetMapfv                (k+9) x 4 x R   see sec 5.1             -
  x MAP1_x                              IsEnabled               (k+9) x B       False                   -
  x MAP2_x                              IsEnabled               (k+9) x B       False                   -

+ = state defined in another extension.
x = state qualified by SELECTED_TEXTURE_TRANSFORM_SGIS
c = state qualified by SELECTED_TEXTURE_COORD_SET_SGIS

New Implementation Dependent State

    Get Value                           Get Command             Type            Minimum Value
    ---------                           -----------             ----            -------------
    MAX_TEXTURES_SGIS                   GetIntegerv             Z+              1
    MAX_TEXTURE_COORD_SETS_SGIS         GetIntegerv             Z+              1