| Name |
| |
| MESA_ycbcr_texture |
| |
| Name Strings |
| |
| GL_MESA_ycbcr_texture |
| |
| Contact |
| |
| Brian Paul, Tungsten Graphics, Inc. (brian '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 extensions is written against the OpenGL 1.4 Specification. |
| NV_texture_rectangle effects the definition of this extension. |
| |
| Overview |
| |
| This extension supports texture images in the YCbCr format. There is |
| no support for converting YCbCr images to RGB or vice versa. The |
| intention is for YCbCr image data to be directly sent to the renderer |
| without any pixel transfer operations. 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: |
| |
| GL_YCBCR_MESA 0x8757 |
| |
| Accepted by the <type> parameter of TexImage2D and TexSubImage2D: |
| |
| GL_UNSIGNED_SHORT_8_8_MESA 0x85BA /* same as Apple's */ |
| GL_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 102, |
| 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 3 YCBCR_422_MESA |
| UNSIGNED_SHORT_8_8_REV_MESA ushort 3 YCBCR_422_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 102, |
| add the following to Table 3.12 (Packed pixel fiedl assignments): |
| |
| First Second Third Fourth |
| Format Element Element Element Element |
| ------ ------- ------- ------- ------- |
| YCBCR_422_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. |
| |
| |
| 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 |
