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Name Strings
Mathias Heyer, NVIDIA Corporation (mheyer 'at'
Jeff Bolz, NVIDIA
Piers Daniell, NVIDIA
Daniel Koch, NVIDIA
Mathias Heyer, NVIDIA
Jon Leech
Copyright (c) 2012-2015 The Khronos Group Inc. Copyright terms at
Specification Update Policy
Khronos-approved extension specifications are updated in response to
issues and bugs prioritized by the Khronos OpenGL ES Working Group. For
extensions which have been promoted to a core Specification, fixes will
first appear in the latest version of that core Specification, and will
eventually be backported to the extension document. This policy is
described in more detail at
Ratified by the Khronos Board of Promoters on 2014/03/14.
Last Modified Date: May 13, 2015
Revision: 10
OpenGL ES Extension #173
OpenGL ES 3.1 is required.
This extension is written against the OpenGL ES 3.1 (April 29, 2015)
This extension accepts STENCIL_INDEX8 as a texture internal format, and
adds STENCIL_INDEX8 to the required internal format list. This removes the
need to use renderbuffers if a stencil-only format is desired.
New Procedures and Functions
New Tokens
Accepted by the <format> parameter of TexImage3D, TexImage2D
TexSubImage3D and TexSubImage2D:
STENCIL_INDEX 0x1901 /* existing enum */
Accepted by the <internalformat> parameter of TexImage3D, TexImage2D,
TexStorage3D, TexStorage2D, TexStorage3DMultisample
and TexStorage2DMultisample:
STENCIL_INDEX8 0x8D48 /* existing enum */
Additions to Section 8.4.2 of the OpenGL ES 3.1 Specification
(Transfer of Pixel Rectangles)
Add to table 8.2 "Valid combinations of <format>, <type> and sized
Format Type External Bytes Internal Format
per Pixel
--------------- --------------- --------------- ---------------
Add to table 8.5 "Pixel data formats":
Format Name | Element Meaning and Order | Target buffer
STENCIL_INDEX | Stencil Index | Stencil
Additions to Section 8.5 of the OpenGL ES 3.1 Specification
(Texture Image Specification)
Modify the third paragraph from the bottom of p. 150 to include
"Textures with a base internal format of DEPTH_COMPONENT, DEPTH_STENCIL,
or STENCIL_INDEX are supported by texture image specification commands
only if <target> is..."
Additions to Section 8.6 of the OpenGL ES 3.1 Specification
(Alternate Texture Image Specification Commands)
In table 8.16 "Valid CopyTexImage source framebuffer/destination texture
base internal format combinations)", add row 'S' and column 'S' and
leave all the format combinations involving 'S' marked unsupported.
Additions to Section 8.16 of the OpenGL ES 3.1 Specification
(Texture Completeness)
Add a bullet to the list of reasons a texture would be incomplete, on p,
- The internal format of the texture is STENCIL_INDEX and either the
magnification filter is not NEAREST, or the minification filter is
Additions to Section 8.19.1 of the OpenGL ES 3.1 Specification
(Depth Texture Comparison Mode)
Modify the description of computing R_t on p. 195:
"Then the effective texture value is computed as follows:
- If the base internal format is STENCIL_INDEX, then r = St
- If the base internal format is DEPTH_STENCIL and ..."
Changes to Section of the OpenGL ES 3.1 Specification
(Texture Access)
Change the next-to-last paragraph of the section (at the bottom of p.
272) to:
"Texture lookups involving texture objects with an internal format of
DEPTH_STENCIL can read the stencil value as described in section 8.19 by
Textures with a STENCIL_INDEX base internal format may also be used to
read stencil data. The stencil value is read as an integer and assigned
to R_t. An unsigned integer sampler should be used to lookup the stencil
component, otherwise the results are undefined.
If a sampler is used in a shader..."
Additions to Section 16.1.2 of the OpenGL ES 3.1 Specification
Add STENCIL_INDEX to the third paragraph following the prototype
for ReadPixels on p. 338:
"The second is an implementation-chosen format from among those defined
in table 8.2, excluding formats DEPTH_COMPONENT, DEPTH_STENCIL and
STENCIL_INDEX. The values of <format> ..."
New Implementation Dependent State
New State
Modifications to the OpenGL ES Shading Language Specification, Version 3.10
An INVALID_OPERATION error is generated by TexImage3D, TexImage2D,
TexSubImage3D, TexSubImage2D if <format> is STENCIL_INDEX and the
base internal format is not <STENCIL_INDEX>.
An INVALID_OPERATION error is generated by TexImage3D, TexImage2D,
TexSubImage3D or TexSubImage2D, if <format> is STENCIL_INDEX and
<target> is not one of TEXTURE_2D, TEXTURE_2D_ARRAY and TEXTURE_CUBE_MAP_*.
An INVALID_OPERATION error is generated by TexImage3D, TexImage2D,
TexSubImage3D or TexSubImage2D, if <format> is STENCIL_INDEX and
<type> is not <UNSIGNED_BYTE>
An INVALID_OPERATION error is generated by TexImage3D and TexImage2D,
if <format> is <STENCIL_INDEX> and internal format is not <STENCIL_INDEX8>
(1) What is the interaction with OpenGL ES 3.1's
RESOLVED: That piece of state is ignored because the base internal format
of a STENCIL_INDEX texture is not DEPTH_STENCIL.
(2) Does the presence of this extension imply that the implementation
supports a true 8-bit stencil buffer?
RESOLVED: No, some OpenGL implementations may internally expand a
format like STENCIL_INDEX8 to DEPTH24_STENCIL8, but will make such a format
behave as if there were no depth bits. Additionally, implementations may
not support independent depth and stencil attachments; a framebuffer with a
STENCIL_INDEX8 stencil attachment and a DEPTH_COMPONENT24 depth attachment
may be treated as unsupported (FRAMEBUFFER_UNSUPPORTED).
(3) Should we support stencil formats that have a number of bits that is
not exactly supported in the implementation? 8-bits is universally
supported, but 1/4/16-bits are not.
RESOLVED: Only accept STENCIL_INDEX8, which is universally supported.
Revision History
Rev. Date Author Changes
---- -------- -------- -----------------------------------------------
1 03/20/12 jbolz Internal revisions.
2 05/30/12 dgkoch Add tokens and errors section.
Update errors for GetTexImage.
3 07/23/13 mheyer Take ARB_texture_stencil8 and reword it for
ES 3.0
4 08/06/13 mheyer Allow NEAREST_MIPMAP_NEAREST as filter.
5 08/30/13 mheyer Add interactions with multisample textures.
6 09/03/13 mheyer CopyTexImage2D does not support stencil textures
7 10/16/13 mheyer Add entry to Table 3.5, added modification to
section 2.11.9 and extended Errors section.
8 01/20/14 dkoch Fix name of interacting extension.
Remove trailing whitespace.
9 01/30/14 dkoch Rename to OES.
10 05/13/15 Jon Leech Rebase on OpenGL ES 3.1, which is required
in any case.