--- /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