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Diffstat (limited to 'docs/specs/MESA_ycbcr_texture.spec')
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diff --git a/docs/specs/MESA_ycbcr_texture.spec b/docs/specs/MESA_ycbcr_texture.spec new file mode 100644 index 00000000000..6a730e81ccf --- /dev/null +++ b/docs/specs/MESA_ycbcr_texture.spec @@ -0,0 +1,204 @@ +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 |