| Name |
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| SGIX_color_table_index_mode |
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| Name Strings |
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| GL_SGIX_color_table_index_mode |
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| Version |
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| $Date: 1997/04/07 20:05:51 $ $Revision: 1.1 $ |
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| Number |
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| XXX |
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| Dependencies |
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| SGI_color_table affects the definition of this extension |
| |
| Overview |
| |
| Currently the mapping from a color value to an index is defined mathematically as |
| clamp your (float) value to [0,1], multiply by the table size-1 and round. |
| |
| This is less interesting for an s10e5 format pixel where we would like to use |
| "all" the bits as an index, not just the bits that are good in [0,1]. |
| |
| The answer is to specify that the float color value is converted to the framebuffer |
| format and then the high order bits are taken as necessary to index the power of |
| two lookup table. In the silly case where the table is larger than the number of |
| bits we have, the lsb's of the index are 0 filled. |
| |
| Issues |
| |
| the down and dirty nature of this extension may offend the puritanical sensibilities of |
| certain clean minded types. |
| |
| New Procedures and Functions |
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| None. |
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| New Tokens |
| |
| Accepted by the <pname> parameter of ColorTableParameterivSGI, |
| ColorTableParameterfvSGI, GetColorTableParameterivSGI, and |
| GetColorTableParameterfvSGI: |
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| COLOR_TABLE_INDEX_MODE 0xXXXX |
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| Accepted by the <params> parameter of ColorTableParameterivSGI, |
| ColorTableParameterfvSGI |
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| COLOR_TABLE_BITS 0xXXXX |
| COLOR_TABLE_ARITH 0xXXXX |
| |
| Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation) |
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| None |
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| Additions to Chapter 3 of the 1.0 Specification (Rasterization) |
| |
| if the value of COLOR_TABLE_INDEX_MODE is COLOR_TABLE_BITS then |
| XXX Specify that the index is computed by converting the float color value to |
| the framebuffer format and taking the required most significan bits as an |
| index into the color table. |
| |
| if the value of COLOR_TABLE_INDEX_MODE is COLOR_TABLE_ARITH then |
| do it like it already says. |
| |
| Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations |
| and the Framebuffer) |
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| None |
| |
| |
| Additions to Chapter 5 of the 1.0 Specification (Special Functions) |
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| None |
| |
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| Additions to Chapter 6 of the 1.0 Specification (State and State Requests) |
| |
| |
| Additions to the GLX Specification |
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| None |
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| GLX Protocol |
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| XXX |
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| Dependencies on SGI_color_table |
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| If SGI_color_table must be supported to support SGI_color_table_index_mode. |
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| Errors |
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| XXX incomplete |
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| New State |
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| Get Value Get Command Type Initial Value Attribute |
| --------- ----------- ---- ------------- --------- |
| COLOR_TABLE_INDEX_MODE GetColorTableParameterfvSGI Z2 COLOR_TABLE_ARITH pixel |
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| New Implementation Dependent State |
| |