| Name |
| |
| CHROMIUM_flipy |
| |
| Name Strings |
| |
| GL_CHROMIUM_flipy |
| |
| Version |
| |
| Last Modifed Date: April 9, 2012 |
| |
| Dependencies |
| |
| OpenGL ES 2.0 is required. |
| |
| Overview |
| |
| This extension adds the ability to vertically flip texture image data when |
| calling TexImage2D and TexSubImage2D. |
| |
| Issues |
| |
| |
| New Tokens |
| |
| Accepted by the <param> parameter of PixelStorei: |
| |
| UNPACK_FLIP_Y_CHROMIUM 0x9240 |
| |
| Additions to the OpenGL ES 2.0 Specification |
| |
| Modifications to Table 3.1 (PixelStore Parameters) |
| |
| Add the following entry: |
| |
| Parameter Name Type Initial Value Valid Range |
| ============== ==== ============= =========== |
| UNPACK_FLIP_Y_CHROMIUM boolean FALSE {TRUE, FALSE} |
| |
| Modifications to 3.6.2 Transfer of Pixel Rectangles, in the Unpacking |
| section: |
| |
| Change |
| "If p indicates the location in memory of the first element of the first |
| row, then the first element of the Nth row is indicated by |
| p + Nk (3.9)" |
| to |
| "If p indicates the location in memory of the first element of the first |
| row, then the first element of the Nth row is indicated by |
| p + Nk (3.9) |
| if UNPACK_FLIP_Y is FALSE. Otherwise, the first element of the Nth row |
| is indicated by |
| p - Nk (3.10) |
| |
| After the sentence |
| |
| "If the number of bits per element is not 1, 2, 4, or 8 times the number |
| of bits in a GL ubyte, then k = nl for all values of a." |
| |
| insert: |
| |
| "If UNPACK_FLIP_Y_CHROMIUM is FALSE then p is equal to pixels. Otherwise |
| p is pixels + (height - 1)k." |
| |
| Interactions with GL_EXT_unpack_subimage |
| |
| Do not add the sentence "If UNPACK_FLIP_Y_CHROMIUM is FALSE ..." described |
| in this extension. Instead do the following after applying |
| GL_EXT_unpack_subimage: |
| |
| Change |
| |
| "There is a mechanism for selecting a sub-rectangle of groups |
| from a larger containing rectangle. This mechanism relies on |
| three integer parameters: UNPACK_ROW_LENGTH, UNPACK_SKIP_ROWS, |
| and UNPACK_SKIP_PIXELS. Before obtaining the first group from |
| memory, the pointer supplied to TexImage2D is effectively |
| advanced by (UNPACK_SKIP_PIXELS)n + (UNPACK_SKIP_ROWS)k |
| elements. Then <width> groups are obtained from contiguous |
| elements in memory (without advancing the pointer), after |
| which the pointer is advanced by k elements. <height> sets of |
| <width> groups of values are obtained this way. See figure |
| 3.6." |
| |
| to |
| |
| "There is a mechanism for selecting a sub-rectangle of groups |
| from a larger containing rectangle. This mechanism relies on |
| three integer parameters: UNPACK_ROW_LENGTH, UNPACK_SKIP_ROWS, |
| and UNPACK_SKIP_PIXELS. IF UNPACK_FLIP_Y_CHROMIUM is FALSE then |
| p, the location of the first element of the first |
| group, is pixels + (UNPACK_SKIP_PIXELS)n + (UNPACK_SKIP_ROWS)k. |
| When UNPACK_FLIP_Y_CHROMIUM is TRUE then p is pixels + |
| (UNPACK_SKIP_PIXELS)n + (UNPACK_SKIP_ROWS + height - 1)k. After |
| p is determined <width> groups are obtained from contiguous |
| elements in memory (without advancing the pointer), after which |
| the pointer is advanced by +/-k elements depending on the value |
| of UNPACK_CHROMIUM_FLIP_Y. <height> sets of <width> groups of |
| values are obtained this way. See figure 3.6." |
| |
| New Procedures and Functions |
| |
| None. |
| |
| Errors |
| |
| None. |
| |
| New State |
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| None. |
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| Revision History |
| |
| 7/22/2011 Documented the extension |
| 4/09/2012 Added more documentation and described interactions with |
| GL_EXT_unpack_subimage |