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Name
MESA_packed_depth_stencil
Name Strings
GL_MESA_packed_depth_stencil
Contact
Keith Whitwell, VA Linux Systems Inc. (keithw 'at' valinux.com)
Brian Paul, VA Linux Systems Inc. (brianp 'at' valinux.com)
Status
Obsolete.
Version
$Id: MESA_packed_depth_stencil.spec,v 1.1.1.3 2004/08/12 23:43:24 anholt Exp $
Number
???
Dependencies
EXT_abgr affects the definition of this extension
SGIS_texture4D affects the definition of this extension
EXT_cmyka affects the definition of this extension
ARB_packed_pixels affects the definition of this extension
Overview
Provides a mechanism for DrawPixels and ReadPixels to efficiently
transfer depth and stencil image data. Specifically, we defined new
packed pixel formats and types which pack both stencil and depth
into one value.
Issues:
1. Is this the right way to distinguish between 24/8 and 8/24
pixel formats? Should we instead provide both:
GL_DEPTH_STENCIL_MESA
GL_STENCIL_DEPTH_MESA
And perhaps just use GL_UNSIGNED_INT, GL_UNSIGNED_SHORT ?
2. If not, is it correct to use _REV to indicate that stencil
preceeds depth in the 1_15 and 8_24 formats?
3. Do we really want the GL_UNSIGNED_SHORT formats?
New Procedures and Functions
None.
New Tokens
Accepted by the <format> parameter of ReadPixels and DrawPixels:
GL_DEPTH_STENCIL_MESA 0x8750
Accepted by the <type> parameter of ReadPixels and DrawPixels:
GL_UNSIGNED_INT_24_8_MESA 0x8751
GL_UNSIGNED_INT_8_24_REV_MESA 0x8752
GL_UNSIGNED_SHORT_15_1_MESA 0x8753
GL_UNSIGNED_SHORT_1_15_REV_MESA 0x8754
Additions to Chapter 2 of the 1.1 Specification (OpenGL Operation)
None
Additions to Chapter 3 of the 1.1 Specification (Rasterization)
One entry is added to table 3.5 (DrawPixels and ReadPixels formats).
The new table is:
Target
Format Name Buffer Element Meaning and Order
----------- ------ -------------------------
COLOR_INDEX Color Color index
STENCIL_INDEX Stencil Stencil index
DEPTH_COMPONENT Depth Depth component
RED Color R component
GREEN Color G component
BLUE Color B component
ALPHA Color A component
RGB Color R, G, B components
RGBA Color R, G, B, A components
BGRA Color B, G, R, A components
ABGR_EXT Color A, B, G, R components
CMYK_EXT Color Cyan, Magenta, Yellow, Black components
CMYKA_EXT Color Cyan, Magenta, Yellow, Black, A components
LUMINANCE Color Luminance component
LUMINANCE_ALPHA Color Luminance, A components
DEPTH_STENCIL Depth, Depth component, stencil index.
Stencil
Table 3.5: DrawPixels and ReadPixels formats. The third column
gives a description of and the number and order of elements in a
group.
Add to the description of packed pixel formats:
<type> Parameter Data of Matching
Token Name Type Elements Pixel Formats
---------------- ---- -------- -------------
UNSIGNED_BYTE_3_3_2 ubyte 3 RGB
UNSIGNED_BYTE_2_3_3_REV ubyte 3 RGB
UNSIGNED_SHORT_5_6_5 ushort 3 RGB
UNSIGNED_SHORT_5_6_5_REV ushort 3 RGB
UNSIGNED_SHORT_4_4_4_4 ushort 4 RGBA,BGRA,ABGR_EXT,CMYK_EXT
UNSIGNED_SHORT_4_4_4_4_REV ushort 4 RGBA,BGRA
UNSIGNED_SHORT_5_5_5_1 ushort 4 RGBA,BGRA,ABGR_EXT,CMYK_EXT
UNSIGNED_SHORT_1_5_5_5_REV ushort 4 RGBA,BGRA
UNSIGNED_INT_8_8_8_8 uint 4 RGBA,BGRA,ABGR_EXT,CMYK_EXT
UNSIGNED_INT_8_8_8_8_REV uint 4 RGBA,BGRA
UNSIGNED_INT_10_10_10_2 uint 4 RGBA,BGRA,ABGR_EXT,CMYK_EXT
UNSIGNED_INT_2_10_10_10_REV uint 4 RGBA,BGRA
UNSIGNED_SHORT_15_1_MESA ushort 2 DEPTH_STENCIL_MESA
UNSIGNED_SHORT_1_15_REV_MESA ushort 2 DEPTH_STENCIL_MESA
UNSIGNED_SHORT_24_8_MESA ushort 2 DEPTH_STENCIL_MESA
UNSIGNED_SHORT_8_24_REV_MESA ushort 2 DEPTH_STENCIL_MESA
UNSIGNED_INT_8_24:
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+-----------------------+-----------------------------------------------------------------------+
| | |
+-----------------------+-----------------------------------------------------------------------+
first second
element element
UNSIGNED_INT_24_8:
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+----------------------------------------------------------------------+------------------------+
| | |
+----------------------------------------------------------------------+------------------------+
first second
element element
UNSIGNED_SHORT_15_1:
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+-----------------------------------------------------------+---+
| | |
+-----------------------------------------------------------+---+
first second
element element
UNSIGNED_SHORT_1_15_REV:
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+---+-----------------------------------------------------------+
| | |
+---+-----------------------------------------------------------+
second first
element element
The assignment of elements to fields in the packed pixel is as
described in the table below:
First Second Third Fourth
Format Element Element Element Element
------ ------- ------- ------- -------
RGB red green blue
RGBA red green blue alpha
BGRA blue green red alpha
ABGR_EXT alpha blue green red
CMYK_EXT cyan magenta yellow black
DEPTH_STENCIL_MESA depth stencil
Additions to Chapter 4 of the 1.1 Specification (Per-Fragment Operations
and the Frame Buffer)
The new format is added to the discussion of Obtaining Pixels from the
Framebuffer. It should read " If the <format> is one of RED, GREEN,
BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA, and
the GL is in color index mode, then the color index is obtained."
The new format is added to the discussion of Index Lookup. It should
read "If <format> is one of RED, GREEN, BLUE, ALPHA, RGB, RGBA,
ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA, then the index is used to
reference 4 tables of color components: PIXEL_MAP_I_TO_R,
PIXEL_MAP_I_TO_G, PIXEL_MAP_I_TO_B, and PIXEL_MAP_I_TO_A."
Additions to Chapter 5 of the 1.1 Specification (Special Functions)
None
Additions to Chapter 6 of the 1.1 Specification (State and State Requests)
None
Additions to the GLX Specification
None
GLX Protocol
TBD
Errors
None
New State
None
Revision History
Version 1.0 - 23 Sep 2000
Keith's original version.
Version 1.1 - 3 Nov 2000
Brian's edits, assigned values to new enums.
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