+++ /dev/null
-Name
-
- MESA_ycbcr_texture
-
-Name Strings
-
- GL_MESA_ycbcr_texture
-
-Contact
-
- Brian Paul, Tungsten Graphics, Inc. (brian.paul 'at' tungstengraphics.com)
- Keith Whitwell, Tungsten Graphics, Inc. (keith 'at' tungstengraphics.com)
-
-Status
-
- Shipping (Mesa 4.0.4 and later)
-
-Version
-
- 1.0
-
-Number
-
- TBD
-
-Dependencies
-
- OpenGL 1.0 or later is required
- This extension is written against the OpenGL 1.4 Specification.
- NV_texture_rectangle effects the definition of this extension.
-
-Overview
-
- This extension supports texture images stored in the YCbCr format.
- There is no support for converting YCbCr images to RGB or vice versa
- during pixel transfer. The texture's YCbCr colors are converted to
- RGB during texture sampling, after-which, all the usual per-fragment
- operations take place. Only 2D texture images are supported (not
- glDrawPixels, glReadPixels, etc).
-
- A YCbCr pixel (texel) is a 16-bit unsigned short with two components.
- The first component is luminance (Y). For pixels in even-numbered
- image columns, the second component is Cb. For pixels in odd-numbered
- image columns, the second component is Cr. If one were to convert the
- data to RGB one would need to examine two pixels from columns N and N+1
- (where N is even) to deduce the RGB color.
-
-IP Status
-
- None
-
-Issues
-
- None
-
-New Procedures and Functions
-
- None
-
-New Tokens
-
- Accepted by the <internalFormat> and <format> parameters of
- TexImage2D and TexSubImage2D:
-
- YCBCR_MESA 0x8757
-
- Accepted by the <type> parameter of TexImage2D and TexSubImage2D:
-
- UNSIGNED_SHORT_8_8_MESA 0x85BA /* same as Apple's */
- UNSIGNED_SHORT_8_8_REV_MESA 0x85BB /* same as Apple's */
-
-Additions to Chapter 2 of the OpenGL 1.4 Specification (OpenGL Operation)
-
- None
-
-Additions to Chapter 3 of the OpenGL 1.4 Specification (Rasterization)
-
- In section 3.6.4, Rasterization of Pixel Rectangles, on page 101,
- add the following to Table 3.8 (Packed pixel formats):
-
- type Parameter GL Data Number of Matching
- Token Name Type Components Pixel Formats
- -------------- ------- ---------- -------------
- UNSIGNED_SHORT_8_8_MESA ushort 2 YCBCR_MESA
- UNSIGNED_SHORT_8_8_REV_MESA ushort 2 YCBCR_MESA
-
-
- In section 3.6.4, Rasterization of Pixel Rectangles, on page 102,
- add the following to Table 3.10 (UNSIGNED_SHORT formats):
-
- UNSIGNED_SHORT_8_8_MESA:
-
- 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- +-------------------------------+-------------------------------+
- | 1st | 2nd |
- +-------------------------------+-------------------------------+
-
- UNSIGNED_SHORT_8_8_REV_MESA:
-
- 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- +-------------------------------+-------------------------------+
- | 2nd | 1st |
- +-------------------------------+-------------------------------+
-
-
- In section 3.6.4, Rasterization of Pixel Rectangles, on page 104,
- add the following to Table 3.12 (Packed pixel field assignments):
-
- First Second Third Fourth
- Format Element Element Element Element
- ------ ------- ------- ------- -------
- YCBCR_MESA luminance chroma
-
-
- In section 3.8.1, Texture Image Specification, on page 125, add
- another item to the list of TexImage2D and TexImage3D equivalence
- exceptions:
-
- * The value of internalformat and format may be YCBCR_MESA to
- indicate that the image data is in YCbCr format. type must
- be either UNSIGNED_SHORT_8_8_MESA or UNSIGNED_SHORT_8_8_REV_MESA
- as seen in tables 3.8 and 3.10. Table 3.12 describes the mapping
- between Y and Cb/Cr to the components.
- If NV_texture_rectangle is supported target may also be
- TEXTURE_RECTANGLE_NV or PROXY_TEXTURE_RECTANGLE_NV.
- All pixel transfer operations are bypassed. The texture is stored as
- YCbCr, not RGB. Queries of the texture's red, green and blue component
- sizes will return zero. The YCbCr colors are converted to RGB during
- texture sampling using an implementation dependent conversion.
-
-
- In section 3.8.1, Texture Image Specification, on page 126, add
- another item to the list of TexImage1D and TexImage2D equivalence
- exceptions:
-
- * The value of internalformat and format can not be YCBCR_MESA.
-
-
- In section 3.8.2, Alternate Texture Image Specification Commands, on
- page 129, insert this paragraph after the first full paragraph on the
- page:
-
- "If the internal storage format of the image being updated by
- TexSubImage2D is YCBCR_MESA then format must be YCBCR_MESA.
- The error INVALID_OPERATION will be generated otherwise."
-
-
-Additions to Chapter 4 of the OpenGL 1.4 Specification (Per-Fragment
-Operations and the Frame Buffer)
-
- None
-
-Additions to Chapter 5 of the OpenGL 1.4 Specification (Special Functions)
-
- None
-
-Additions to Chapter 6 of the OpenGL 1.4 Specification (State and
-State Requests)
-
- None
-
-Additions to Appendix A of the OpenGL 1.4 Specification (Invariance)
-
- None
-
-Additions to the AGL/GLX/WGL Specifications
-
- None
-
-GLX Protocol
-
- None
-
-Errors
-
- INVALID_ENUM is generated by TexImage2D if <internalFormat> is
- MESA_YCBCR but <format> is not MESA_YCBCR.
-
- INVALID_ENUM is generated by TexImage2D if <format> is MESA_YCBCR but
- <internalFormat> is not MESA_YCBCR.
-
- INVALID_VALUE is generated by TexImage2D if <format> is MESA_YCBCR and
- <internalFormat> is MESA_YCBCR and <border> is not zero.
-
- INVALID_OPERATION is generated by TexSubImage2D if the internal image
- format is YCBCR_MESA and <format> is not YCBCR_MESA.
-
- INVALID_OPERATION is generated by CopyTexSubImage2D if the internal
- image is YCBCR_MESA.
-
-New State
-
- Edit table 6.16 on page 231: change the type of TEXTURE_INTERNAL_FORMAT
- from n x Z42 to n x Z43 to indicate that internal format may also be
- YCBCR_MESA.
-
-Revision History
-
- 20 September 2002 - Initial draft
- 29 April 2003 - minor updates
- 3 September 2003 - further clarify when YCbCr->RGB conversion takes place
- 19 September 2003 - a few more updates prior to submitting to extension
- registry.
- 3 April 2004 - fix assorted inaccuracies
projects / mesa.git / blobdiff