Name

    ATI_envmap_bumpmap

Name Strings

    GL_ATI_envmap_bumpmap

Contact

    Dan Ginsburg, AMD (dan.ginsburg 'at' amd.com)


Version

    Date: 11/04/2006
    Revision: 1.02

Number

    244

Dependencies

    EXT_texture_env_combine is required by this extension.
    ARB_multitexture is required by this extension.

Overview

    This extension adds environment mapped bump mapping (EMBM) to the GL.
    The method exposed by this extension is to use a dependent texture
    read on a bumpmap (du,dv) texture to offset the texture coordinates
    read into a map on another texture unit.  This (du,dv) offset is also 
    rotated through a user-specified rotation matrix to get the texture 
    coordinates into the appropriate space.

    A new texture format is introduced in order for specifying the (du,dv)
    bumpmap texture.  This map represents -1 <= du,dv <= 1 offsets to
    be applied to the texture coordinates used to read into the base
    map.  Additionally, the (du,dv) offsets are transformed by a rotation
    matrix that this extension allows the user to specify.  Further, a 
    new color operation is added to EXT_texture_env_combine to specify 
    both that bumpmapping is enabled and which texture unit to apply 
    the bump offset to.  
    
Issues
    
    None known.

New Procedures and Functions

    void TexBumpParameter[i|f]vATI(enum pname, TYPE *param)

    void GetTexBumpParameter[i|f]vATI(enum pname, TYPE *param)

New Tokens

    Accepted by the <pname> parameter of TexBumpParameter[i|f]vATI

        BUMP_ROT_MATRIX_ATI            0x8775
    
    Accepted by the <pname> parameter of GetTexBumpParameter[i|f]vATI

        BUMP_ROT_MATRIX_ATI                
        BUMP_ROT_MATRIX_SIZE_ATI       0x8776
        BUMP_NUM_TEX_UNITS_ATI         0x8777
        BUMP_TEX_UNITS_ATI             0x8778

    Accepted by the <format> parameter of GetTexImage and TexImage2D

        DUDV_ATI                       0x8779
	DU8DV8_ATI                     0x877A

    Accepted by the <components> parameter of TexImage2D

        DUDV_ATI
	DU8DV8_ATI

    Accepted by the <params> parameter of TexEnvf, TexEnvi, TexEnvfv,
    and TexEnviv when the <pname> parameter value is COMBINE_RGB_EXT

        BUMP_ENVMAP_ATI                0x877B

    Accepted by the <pname> parameter of TexEnvf, TexEnvi, TexEnvfv,
    and TexEnviv when the <target> parameter value is TEXTURE_ENV

        BUMP_TARGET_ATI                0x877C

    Accepted by the <params> parameter of TexEnvf, TexEnvi, TexEnvfv,
    and TexEnviv when the <pname> parameter value is BUMP_TARGET_ATI    

        TEXTURE0_ARB
        TEXTURE1_ARB
        TEXTURE2_ARB
        TEXTURE3_ARB
        TEXTURE4_ARB
        TEXTURE5_ARB
        TEXTURE6_ARB
        TEXTURE7_ARB
        TEXTURE8_ARB
        TEXTURE9_ARB
        TEXTURE10_ARB
        TEXTURE11_ARB
        TEXTURE12_ARB
        TEXTURE13_ARB
        TEXTURE14_ARB
        TEXTURE15_ARB
        TEXTURE16_ARB
        TEXTURE17_ARB
        TEXTURE18_ARB
        TEXTURE19_ARB
        TEXTURE20_ARB
        TEXTURE21_ARB
        TEXTURE22_ARB
        TEXTURE23_ARB
        TEXTURE24_ARB
        TEXTURE25_ARB
        TEXTURE26_ARB
        TEXTURE27_ARB
        TEXTURE28_ARB
        TEXTURE29_ARB
        TEXTURE30_ARB
        TEXTURE31_ARB


Additions to Chapter 2 of the OpenGL 1.2.1 Specification (Operation):

    None

Additions to Chapter 3 of the OpenGL 1.2.1 Specification (Rasterization)

    - (p.144, Table 3.15) Add row to table:

    "Base Internal Format            RGBA Values      Internal Components
     --------------------            -----------      -------------------
     DUDV_ATI                        undefined        U,V"

    - (p. 155, Table 3.16) Add rows to table, add last two columns:

    "Sized               Base             R    G    B    A    L    I    U    V
     Internal Format     Internal Format  bits bits bits bits bits bits bits bits
     ---------------     ---------------  ---- ---- ---- ---- ---- ---- ---- ----
     DU8DV8_ATI          DUDV_ATI                                       8    8"

    - (p. 136 Table 3.18) Add Row:

    "Base               REPLACE            MODULATE
     Internal Format    Texture Function   Texture Function
     ---------------    ----------------   ----------------
     DUDV_ATI           undefined          undefined"

    - (p. 137 Table 3.19) Add Row:

    "Base               DECAL              BLEND
     Internal Format    Texture Function   Texture Function
     ---------------    ----------------   ----------------
     DUDV_ATI           undefined          undefined"

	
        Table 3.23: Correspondence of texture components to source
        components for COMBINE_RGB_EXT and COMBINE_ALPHA_EXT arguments"

    - (p.138, add new section 3.8.11)

    "3.8.11 Texture Bump Parameters

    The parameters for environment mapped bump mapping are set through
    the entry point:

       void TexBumpParameter[i|f]vATI(enum pname, TYPE *param)

    When pname is BUMP_ROT_MATRIX_ATI, the rotation matrix applied to
    each (du, dv) coordinate read from the bumpmap is specified
    (see section 3.8.9 on environment mapped bump mapping).  The size 
    of the rotation matrix can vary across implementations (to allow for 
    future expansion with support for offsets to more than just two 
    coordinates).  This size can be queried for using:

       void GetTexBumpParamter[i|f]vATI(enum pname, TYPE *param)

    with pname as BUMP_ROT_MATRIX_SIZE_ATI.  This returns the number
    of entries in the BUMP_ROT_MATRIX.  When pname is BUMP_NUM_TEX_UNITS_ATI,
    the number of texture units that support bump mapping is returned.  
    Given this, an array of supported texture units that support bumpmapping 
    can be queried.  When pname is BUMP_TEX_UNITS_ATI, an array of size 
    BUMP_NUM_TEX_UNITS_ATI is returned in which each element is one of the 
    valid texture units (TEXTURE0_ARB, TEXTURE1_ARB, etc.)."
 
   - After Table 3.20 in EXT_texture_env_combine:

   "In addition, a special-case COMBINE_RGB_EXT function exists for performing
    environment mapped bump mapping.  This function does not behave as 
    the standard combine functions.  Instead, it specifies that the given
    texture unit has a bumpmap which will be used to offset the texture coordinate
    reads onto another unit.

    The texture unit which the bumpmap will bump is specified by setting the
    BUMP_TARGET_ATI to be a valid texture unit.  

    Environment mapped bump mapping then works as follows:

    The (du,dv) offset map specified on the texture unit with BUMP_ENVMAP_ATI
    will be used to offset the texture coordinates read into the map on the
    BUMP_TARGET_ATI unit.  The (du,dv) texel will be fetched from the bumpmap
    at the texture coordinate specified for the bumpmap.  This (du,dv) texel
    will then be rotated through the BUMP_ROT_MATRIX:

      du' = du * Rot[00] + dv * Rot[01]
      dv' = du * Rot[10] + dv * Rot[11]

    (du',dv') will then be used to offset the (u,v) coordinates used to read
    into the texture on BUMP_TARGET_ATI:

      u = u + du'
      v = v + dv'

    These final coordinates are then used to fetch from the texture on 
    BUMP_TARGET_ATI."

     
    - Change to table 3.23 in EXT_texture_env_combine:
    
    "Base Internal Format		RGB Values	Alpha Value
     --------------------		----------	-----------
     ALPHA                              0,  0,  0       At
     LUMINANCE                          Lt, Lt, Lt      1
     LUMINANCE_ALPHA                    Lt, Lt, Lt      At
     INTENSITY                          It, It, It      It
     RGB                                Rt, Gt, Bt      1
     RGBA                               Rt, Gt, Bt      At
     DUDV_ATI                           0, 0, 0         1
    "


Additions to Chapter 4:

    None

Additions to Chapter 5:

    None

Additions to Chapter 6:

    None

Additions to the GLX Specification

    None


GLX Protocol

    None

Dependencies on EXT_point_parameters

    
Errors
    
    INVALID_ENUM if TexBumpParameter[i|f]vATI is called with pname not equal to
       BUMP_ROT_MATRIX_ATI.

    INVALID_ENUM if GetTexBumpParameter[i|f]vATI is called with pname not equal
       to BUMP_ROT_MATRIX_ATI, BUMP_ROT_MATRIX_SIZE_ATI, BUMP_NUM_TEX_UNITS_ATI,
       or BUMP_TEX_UNITS_ATI.

    INVALID_VALUE if the combineRGB function is set on a unit not supported as
       queried with BUMP_TEX_UNITS_ATI.

New State

    Get Value                   Get Command           Type     Minimum Value  Description
    ---------                   -----------           ----     -------------  -----------
    BUMP_ROT_MATRIX_ATI         GetTexBumpParameterfv n x F    -              Bump rotation matrix on current unit
    BUMP_ROT_MATRIX_SIZE_ATI    GetTexBumpParameteriv Z+       4              Bump rotation matrix size
    BUMP_NUM_TEX_UNITS_ATI      GetTexBumpParameteriv Z+       1              Number of bump texture units
    BUMP_TEX_UNITS_ATI          GetTexBumpParameteriv n x Z+   -              Supported bump texture units  
  

New Implementation Dependent State

    None


Revision History

   Date: 11/4/2006
   Revision: 1.02
      - Updated contact info after ATI/AMD merger.

   Date: 1/09/2003
   Revision: 1.01
      - Added an error condition.

   Date: 8/21/2001
   Revision: 1.0
      - First release.