| Name |
| |
| EXT_shared_texture_palette |
| |
| Name Strings |
| |
| GL_EXT_shared_texture_palette |
| |
| Contact |
| |
| Jon Leech, SGI (ljp 'at' sgi.com) |
| Mark J. Kilgard, NVIDIA Corporation (mjk 'at' nvidia.com) |
| |
| Version |
| |
| Last Modified Date: March 24, 2004 |
| Revision: 1.4 |
| |
| Number |
| |
| 141 |
| |
| Support |
| |
| Mesa. |
| |
| Selected NVIDIA GPUs: NV1x (GeForce 256, GeForce2, GeForce4 MX, |
| GeForce4 Go, Quadro, Quadro2), NV2x (GeForce3, GeForce4 Ti, |
| Quadro DCC, Quadro4 XGL), and NV3x (GeForce FX 5xxxx, Quadro FX |
| 1000/2000/3000). NV3 (Riva 128) and NV4 (TNT, TNT2) GPUs and NV4x |
| GPUs do NOT support this functionality (no hardware support). |
| Future NVIDIA GPU designs will no longer support paletted textures. |
| |
| S3 ProSavage, Savage 2000. |
| |
| 3Dfx Voodoo3, Voodoo5. |
| |
| 3Dlabs GLINT. |
| |
| Dependencies |
| |
| EXT_paletted_texture is required. |
| |
| Overview |
| |
| EXT_shared_texture_palette defines a shared texture palette which may be |
| used in place of the texture object palettes provided by |
| EXT_paletted_texture. This is useful for rapidly changing a palette |
| common to many textures, rather than having to reload the new palette |
| for each texture. The extension acts as a switch, causing all lookups |
| that would normally be done on the texture's palette to instead use the |
| shared palette. |
| |
| IP Status |
| |
| None. |
| |
| Issues |
| |
| * Do we want to use a new <target> to ColorTable to specify the |
| shared palette, or can we just infer the new target from the |
| corresponding Enable? |
| |
| * A future extension of larger scope might define a "texture palette |
| object" and bind these objects to texture objects dynamically, rather |
| than making palettes part of the texture object state as the current |
| EXT_paletted_texture spec does. |
| |
| * Should there be separate shared palettes for 1D, 2D, and 3D |
| textures? |
| |
| Probably not; palette lookups have nothing to do with the |
| dimensionality of the texture. If multiple shared palettes |
| are needed, we should define palette objects. |
| |
| * There's no proxy mechanism for checking if a shared palette can |
| be defined with the requested parameters. Will it suffice to |
| assume that if a texture palette can be defined, so can a shared |
| palette with the same parameters? |
| |
| * The changes to the spec are based on changes already made for |
| EXT_paletted_texture, which means that all three documents must |
| be referred to. This is quite difficult to read. |
| |
| * The changes to section 3.8.6, defining how shared palettes are |
| enabled and disabled, might be better placed in section 3.8.1. |
| However, the underlying EXT_paletted_texture does not appear to |
| modify these sections to define exactly how palette lookups are |
| done, and it's not clear where to put the changes. |
| |
| * How does the shared texture palette interact with multitexture |
| support? There is a single global shared texture palette that |
| all texture units utilize (as opposed to a shared texture palette |
| per texture unit). |
| |
| New Procedures and Functions |
| |
| None |
| |
| New Tokens |
| |
| Accepted by the <pname> parameters of GetBooleanv, GetIntegerv, |
| GetFloatv, GetDoublev, IsEnabled, Enable, Disable, ColorTableEXT, |
| ColorSubTableEXT, GetColorTableEXT, GetColorTableParameterivEXT, and |
| GetColorTableParameterfd EXT: |
| |
| SHARED_TEXTURE_PALETTE_EXT 0x81FB |
| |
| Additions to Chapter 2 of the 1.1 Specification (OpenGL Operation) |
| |
| None |
| |
| Additions to Chapter 3 of the 1.1 Specification (Rasterization) |
| |
| Section 3.8, 'Texturing,' subsection 'Texture Image Specification' is |
| modified as follows: |
| |
| In the Palette Specification Commands section, the sentence |
| beginning 'target specifies which texture is to' should be changed |
| to: |
| |
| target specifies the texture palette or shared palette to be |
| changed, and may be one of TEXTURE_1D, TEXTURE_2D, |
| PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, TEXTURE_3D_EXT, |
| PROXY_TEXTURE_3D_EXT, or SHARED_TEXTURE_PALETTE_EXT. |
| |
| In the 'Texture State and Proxy State' section, the sentence |
| beginning 'A texture's palette is initially...' should be changed |
| to: |
| |
| There is also a shared palette not associated with any texture, |
| which may override a texture palette. (Even when multiple texture |
| units are available, there is still only a single shared texture |
| palette.) All palettes are initially... |
| |
| Section 3.8.6, 'Texture Application' is modified by appending the |
| following: |
| |
| Use of the shared texture palette is enabled or disabled using the |
| generic Enable or Disable commands, respectively, with the symbolic |
| constant SHARED_TEXTURE_PALETTE_EXT. |
| |
| The required state is one bit indicating whether the shared palette is |
| enabled or disabled. In the initial state, the shared palettes is |
| disabled. |
| |
| Additions to Chapter 4 of the 1.1 Specification (Per-Fragment Operations |
| and the Frame buffer) |
| |
| Additions to Chapter 5 of the 1.1 Specification (Special Functions) |
| |
| Additions to Chapter 6 of the 1.1 Specification (State and State Requests) |
| |
| In the section on GetTexImage, the sentence beginning 'If format is |
| not COLOR_INDEX...' should be changed to: |
| |
| If format is not COLOR_INDEX, the texture's indices are passed |
| through the texture's palette, or the shared palette if one is |
| enabled, and the resulting components are assigned among R, G, B, |
| and A according to Table 6.1. |
| |
| In the GetColorTable section, the first sentence of the second |
| paragraph should be changed to read: |
| |
| GetColorTableEXT retrieves the texture palette or shared palette |
| given by target. |
| |
| The first sentence of the third paragraph should be changed to read: |
| |
| Palette parameters can be retrieved using |
| void GetColorTableParameterivEXT(enum target, enum pname, int *params); |
| void GetColorTableParameterfvEXT(enum target, enum pname, float *params); |
| target specifies the texture palette or shared palette being |
| queried and pname controls which parameter value is returned. |
| |
| Additions to the GLX Specification |
| |
| None |
| |
| New State |
| |
| Get Value Type Get Command Initial Value Description Sec Attribute |
| -------------------------- ---- --------------------------- ------------- -------------- ----- -------------- |
| SHARED_TEXTURE_PALETTE_EXT B IsEnabled False shared texture 3.8.6 texture/enable |
| palette enable |
| SHARED_TEXTURE_PALETTE_EXT I GetColorTableEXT empty shared texture 3.8 - |
| palette table |
| COLOR_TABLE_FORMAT_EXT Zn GetColorTableParameterivEXT RGBA shared texture 3.8 - |
| palette format |
| COLOR_TABLE_WIDTH_EXT Z+ GetColorTableParameteriv 0 shared texture 3.8 - |
| palette width |
| COLOR_TABLE_x_SIZE_EXT 6xZ+ GetColorTableParameteriv 0 shared texture 3.8 - |
| palette |
| component sizes |
| |
| New Implementation Dependent State |
| |
| None |
| |
| Revision History |
| |
| September 4, 2002 - Add missing IP Status / Contact fields |
| (without bumping the revision) and incorporated Mark's changes |
| into the registry. (Jon Leech) |
| |
| July 10, 2002 (version 1.3) - Added "New State" tables entries. |
| Clarify that there is a single global shared texture palette, |
| rather than a per-texture unit palette when multitexture is |
| available. (Mark Kilgard) |
| |
| March 24, 2004 (version 1.4) - Document vendor support for this |
| extension; note that future NVIDIA GPU designs will not support this |
| extension. (Mark Kilgard) |
| |
