Name
OES_vertex_type_10_10_10_2
Name Strings
GL_OES_vertex_type_10_10_10_2
Contributors
Daniel Ginsburg
Gary King
Petri Kero
Aaftab Munshi
Acorn Pooley
Mark Callow
Ben Bowman
Contact
Aaftab Munshi (amunshi@apple.com)
Notice
Copyright (c) 2006-2013 The Khronos Group Inc. Copyright terms at
http://www.khronos.org/registry/speccopyright.html
IP Status
None.
Status
Ratified by the Khronos BOP, March 20, 2008.
Version
Last Modified Date: July 17, 2007
Number
OpenGL ES Extension #46
Dependencies
This extension is written against the OpenGL ES 2.0 specification
Overview
This extension adds the following data formats:
Two new vertex attribute data formats: a signed 10.10.10.2 and an unsigned
10.10.10.2 vertex data format. These vertex data formats describe a 3- or 4-tuple
stream which can be used to store normals or other attributes in a quantized
form. Normals, tangents, binormals and other vertex attributes can often be specified
at reduced precision without introducing noticeable artifacts, reducing the
amount of memory and memory bandwidth they consume.
Issues
1. Should VertexAttrib{1234}[v] functions take UNSIGNED_INT_10_10_10_2_OES and
INT_10_10_10_2_OES data formats?
RESOLUTION: No.
There is no reason to support this, as these functions are not performance or memory
footprint critical. It is much more important that the vertex data specified using
vertex arrays be able to support these new formats. In addition, we would need a
new data type suffix (similar to "f" for float, "x" for fixed) to denote these two
new data types which is not desirable.
2. Should unsigned 10.10.10.2 RGBA and unsigned 10.10.10 RGB texture formats be
supported by this extension?
RESOLUTION: No.
This extension should focus on enabling 10.10.10{.2} vertex data formats.
The 10.10.10{.2} texture formats should be a separate extension.
New Procedures and Functions
None
New Tokens
Accepted by the parameter of VertexAttribPointer
UNSIGNED_INT_10_10_10_2_OES 0x8DF6
INT_10_10_10_2_OES 0x8DF7
Additions to Chapter 2 of the OpenGL ES 2.0 Specification (OpenGL Operation)
Modifications to section 2.8 (Vertex Arrays)
Add INT_10_10_10_2_OES and UNSIGNED_INT_10_10_10_2_OES as a valid value in Table 2.4.
Add a new section 2.8.1 - UNSIGNED_INT_10_10_10_2_OES and INT_10_10_10_2_OES vertex data formats
UNSIGNED_INT_10_10_10_2_OES and INT_10_10_10_2_OES vertex data formats describe packed
3- or 4- component formats stored in a 32-bit word. These components are expanded to
(x, y, z, 1.0) if = 3, or (x, y, z, w) if = 4.
For UNSIGNED_INT_10_10_10_2_OES vertex data format, the x, y and z components are
represented as a 10-bit unsigned integer value and the w component is represented as a
2-bit unsigned integer value.
For INT_10_10_10_2_OES vertex data format, the x, y and z components are represented
as a 10-bit signed two's complement integer value and the w component is represented
as a 2-bit signed two's complement integer value.
The value is used to indicate whether to normalize the data to
[0, 1] (for unsigned type) or [-1, 1] (for signed type).
The following figure describes how these components are laid out in a 32-bit word.
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
-------------------------------------------------------------------------------------
| x | y | z | w |
-------------------------------------------------------------------------------------
Calls to VertexAttribPointer with of INT_10_10_10_2_OES and
UNSIGNED_INT_10_10_10_2_OES can only be made with = 3 or 4.
values other than 3 or 4 will return an INVALID_VALUE error.
Modifications to table 2.9 (Component conversions)
Add the following entries:
GLType Conversion of (x, y, z) Conversion of w
------- ---------------------- ===============
INT_10_10_10_2_OES (2c + 1)/(2^10 - 1) (2c + 1)/(2^2 - 1)
UNSIGNED_10_10_10_2_OES c / (2^10 - 1) c / (2^2 - 1)
Errors
The error INVALID_VALUE is generated if glVertexAttribPointer is called
with = UNSIGNED_INT_10_10_10_2_OES or INT_10_10_10_2_OES and the
parameter is not set to 3 or 4.
New State
None
Revision History
March 2, 2006 Aaftab Munshi First draft of extension.
March 3, 2006 Aaftab Munshi Changed DEC3N, UDEC3N to INT_10_10_10_2
and UNSIGNED_INT_10_10_10_2 resp.
use parameter to mark
whether data is to be normalized or not.
Changed extension name to GL_ATI_vertex_type_10_10_10_2
Changed error returned from INVALID_ENUM
to INVALID_VALUE if != 3
March 3, 2006 Aaftab Munshi Added Contributors section.
April 10,2006 Aaftab Munshi Support for *_10_10_10_2 as a texture format
June 3, 2006 Aaftab Munshi Renamed to use OES suffixes.
June 14, 2006 Aaftab Munshi Allow 10_10_10_2 to be (x,y,z,1) or (x,y,z,w)
when used as a vertex attribute data format.
Oct 20, 2006 Aaftab Munshi Fixed errors to say 3- or 4- tuples instead
of just 3- tuples.
Jun 13, 2007 Aaftab Munshi Removed 10.10.10{.2} texture formats.
Jul 10, 2007 Aaftab Munshi Clarified that each component is a signed 2's complement
integer or unsigned integer value.
Shorten the extension name from OES_vertex_data_type_10_10_10_2.
Jul 17, 2007 Aaftab Munshi Corrections to section 2.8