NV_EGL_stream_consumer_external
Name
NV_EGL_stream_consumer_external
Name Strings
GL_NV_EGL_stream_consumer_external
Contributors
Acorn Pooley
Contacts
Acorn Pooley, NVIDIA Corporation (apooley 'at' nvidia.com)
Status
DRAFT
Version
Version 3, July 19, 2012
Number
OpenGL ES Extension #104
Dependencies
Requires OpenGL ES 1.1 or OpenGL ES 2.0.
Requires EGL 1.2
Requires the EGL_KHR_stream and EGL_NV_stream_consumer_gltexture
extensions. (Also requires any EGL stream_producer extension to
be useful.)
This extension is written based on the wording of the OpenGL ES
2.0 specification, the OpenGL ES Shading Language version 1.0, the
EGL_KHR_stream extension, and the EGL_NV_stream_consumer_gltexture
extension. On an OpenGL ES 2.0 implementation, ignore sections
which are added only to the OpenGL ES 1.1 specification.
This extension is also written based on the wording of the OpenGL
ES 1.1 specification. On an OpenGL ES 1.X implementation, ignore
sections which are added only to the OpenGL ES 2.0 or OpenGL ES
Shading Language specification. Also ignore all mention of
MAX_VERTEX_TEXTURE_IMAGE_UNITS, and
MAX_COMBINED_TEXTURE_IMAGE_UNITS.
This extension borrows concepts and function names from the
GL_OES_EGL_image_external extension. This extension is compatible
with, but does not require, the GL_OES_EGL_image_external
extension. The presence of the GL_OES_EGL_image_external
extension affects the wording of this extension (and vice versa)
as described in this (the GL_NV_EGL_stream_consumer_external)
extension.
Overview
This extension provides a mechanism for streaming image frames
into a GL texture. This extension defines a new texture target,
TEXTURE_EXTERNAL_OES (which is else defined in the
GL_OES_EGL_image_external extension). This texture target can
only be specified as being the consumer of an EGLStream. (If the
GL_OES_EGL_image_external extension is present it may
alternatively be specified from an EGLImage as described in that
extension.)
There is no support for most of the functions that manipulate
other texture targets (e.g. you cannot use gl*Tex*Image*()
functions with TEXTURE_EXTERNAL_OES). Also, TEXTURE_EXTERNAL_OES
targets never have more than a single LOD level. Because of these
restrictions, it is possible to bind EGLStreams which have
internal formats not otherwise supported by OpenGL ES. For
example some implementations may allow EGLStreams with planar or
interleaved YUV data to be GLES texture target siblings. It is up
to the implementation exactly what formats are accepted.
Glossary
Please see the EGL_KHR_stream specification for a glossary of
terms used by this specification.
New Types
/* (OpenGL ES 2.x only)
* New sampler type allowed by the OpenGL ES Shading Language when
* #extension GL_NV_EGL_stream_consumer_external
* is used, also available if GL_OES_EGL_image_external is
* supported and
* #extension GL_OES_EGL_image_external
* is used.
*/
samplerExternalOES
New Tokens
Accepted as a target in the <target> parameter of BindTexture:
TEXTURE_EXTERNAL_OES 0x8D65
(OpenGL ES 2.x only) Returned in the <type> parameter of GetActiveUniform:
SAMPLER_EXTERNAL_OES 0x8D66
Accepted as <value> in GetIntegerv() and GetFloatv() queries:
TEXTURE_BINDING_EXTERNAL_OES 0x8D67
Accepted as <value> in GetTexParameter*() queries:
REQUIRED_TEXTURE_IMAGE_UNITS_OES 0x8D68
Additions to Chapter 3 of the OpenGL 1.1 or OpenGL 2.0 Specification
- For OpenGL ES 2.0 add a new section: "3.7.14 External Textures,"
which follows section "3.7.13 Texture Objects." For OpenGL ES 1.1
add the new section after section "3.7.11 Texture Objects." If the
GL_OES_EGL_image_external extension is also present, then skip
this addition (use section "3.7.14 External Textures," from that
extension as-is). If the GL_OES_EGL_image_external extension is
not present then insert it as follows (this is a subset of the
section "3.7.14 External Textures" from
GL_OES_EGL_image_external).
"3.7.14 External Textures
External textures cannot be used with TexImage2D,
TexSubImage2D, CompressedTexImage2D, CompressedTexSubImage2D,
CopyTexImage2D, or CopyTexSubImage2D, and an INVALID_ENUM
error will be generated if this is attempted. Their default
min filter is LINEAR. It is an INVALID_ENUM error to set the
min filter value to anything other than LINEAR or NEAREST.
The default s and t wrap modes are CLAMP_TO_EDGE and it is an
INVALID_ENUM error to set the wrap mode to any other value.
(For OpenGL ES 1.x only: The texture parameter GENERATE_MIPMAP
is always FALSE, and setting it to any other value generates
an INVALID_ENUM error. (For OpenGL ES 2.x only: Calling
GenerateMipmaps with <target> set to TEXTURE_EXTERNAL_OES
results in an INVALID_ENUM.)
Each TEXTURE_EXTERNAL_OES texture object may require up to 3
texture image units for each texture unit to which it is
bound. The number of texture image units required by a bound
texture object can be queried using GetTexParameteriv() with
<target> set to the texture target in question, <value> set to
REQUIRED_TEXTURE_IMAGE_UNITS_OES, and ActiveTexture set to the
texture unit to which the texture object is bound. When
<target> is set to TEXTURE_EXTERNAL_OES this value will be
between 1 and 3 (inclusive). For other valid texture targets
this value will always be 1. Note that, when a
TEXTURE_EXTERNAL_OES texture object is bound, the number of
texture image units required by a single texture unit may be
1, 2, or 3, while for other texture objects each texture unit
requires exactly 1 texture image unit.
(For OpenGL ES 1.x only) DrawArrays and DrawElements will fail
and generate an INVALID_OPERATION error if the number of
texture image units required is greater than the number
available. The number of required texture image units is
equal to the sum of the requirements for each enabled texture
unit. For each texture unit the requirement is the value
returned by GetTexParameteriv() when <value> is set to
REQUIRED_TEXTURE_IMAGE_UNITS_OES, <target> is set to the
target which is enabled, and ActiveTexture has been set to the
texture unit in question.
(For OpenGL ES 2.x only) DrawArrays and DrawElements will fail
and generate an INVALID_OPERATION error if the number of
texture image units required is greater than the number
available. The number of required texture image units for
each stage (fragment or vertex) is equal to the sum of the
requirements for each sampler referenced by the stage. A
sampler is considered referenced if its location (returned by
GetUniformLocation) is not -1. For each referenced sampler
the requirement is the value returned by GetTexParameteriv()
when <value> is set to REQUIRED_TEXTURE_IMAGE_UNITS_OES,
<target> is set to the target corresponding to the sampler
type, and ActiveTexture has been set to the texture unit
corresponding to the value of the sampler uniform. The
condition can be detected by calling ValidateProgram.
(For OpenGL ES 2.x only) A shader that uses external texture
samplers may require some number of hidden uniform variables
to implement the conversion from YUV to RGB, and this may
reduce the amount of space available for uniforms defined by
the shader program. This may cause a shader program which was
working to stop working when a different external texture is
used (i.e. when Uniform1i or BindTexture is called). If there
are not enough uniforms available then calls to DrawArrays or
DrawElements will fail and generate an INVALID_OPERATION
error. This condition can be detected by calling
ValidateProgram.
Sampling an external texture will return an RGBA vector in the
same colorspace as the source image frame. If the source
image frame is stored in YUV (or some other basis) then the
YUV values will be transformed to RGB values. (But these RGB
values will be in the same colorspace as the original image.
Colorspace here includes the linear or non-linear encoding of
the samples. For example, if the original image is in the sRGB
color space then the RGB value returned by the sampler will
also be sRGB, and if the original image is stored in ITU-R
Rec. 601 YV12 then the RGB value returned by the sampler will
be an RGB value in the ITU-R Rec. 601 colorspace.) The
parameters of the transformation from one basis (e.g. YUV) to
RGB (color conversion matrix, sampling offsets, etc) are taken
from the producer of the EGLStream that is associated with the
external texture.
If the image frames in the EGLStream contain alpha values then
the value of the alpha component returned is taken from the
image; otherwise the alpha component is 1.0.
- In both OpenGL ES 1.x and OpenGL ES 2.0 add a new subsection after
the previously described "3.7.14 External Textures" section:
"3.7.14.1 External Textures as Stream Consumers
To use a TEXTURE_EXTERNAL_OES texture as the consumer of an
EGLStream, bind the texture to the active texture unit, and
call eglStreamConsumerGLTextureExternalNV() as described in the
EGL_NV_stream_consumer_gltexture extension. The EGLStream
must be in the EGL_STREAM_STATE_CREATED_KHR state (i.e. it
must not be associated with any consumer or producer yet).
The width, height, format, type, internalformat, border, and
image data of the TEXTURE_EXTERNAL_OES texture will all be
determined based on the specified EGLStream <stream> once
<stream> is associated with a producer. Until <stream> is
associated with a producer these attributes are undefined.
Once <stream> is associated with a producer and the producer
has inserted one (or more) images into <stream> (as described
in the EGL_NV_stream_consumer_gltexture extension) these
attributes are determined (internally by the implementation),
but they are not exposed to the GL client and there is no way
to query their values.
(Add this paragraph only if OES_EGL_image_external is also
supported.) If the TEXTURE_EXTERNAL_OES texture is already
bound to an EGLImage then that binding is broken when the
texture becomes the consumer of <stream> (i.e. when
eglStreamConsumerGLTextureNV() returns successfully).
The TEXTURE_EXTERNAL_OES texture remains the consumer of
<stream> until the first of any of these events occur:
- The texture is associated with a different EGLStream
(with a later call to eglStreamConsumerGLTextureNV).
- The texture is bound to an EGLImage (with a call to
EGLImageTargetTexture2DOES).
- The texture is deleted in a call to DeleteTextures().
When any of these events occurs the texture is no longer the
consumer of <stream>, and <stream> transitions to the
EGL_STREAM_STATE_DISCONNECTED_KHR state (as described in the
EGL_NV_stream_consumer_gltexture and EGL_KHR_stream
extensions).
Sampling an external texture which is not the consumer of any
EGLStream and is not associated with any EGLImage sibling will
return a sample value of (0,0,0,1).
Sampling an external texture which is the consumer of an
EGLStream will return a sample value of (0,0,0,1) unless an
image frame is currently 'latched' into the texture. An image
frame is 'latched' into the texture by any successful call to
eglStreamConsumerAcquireNV (as described in the
EGL_NV_stream_consumer_gltexture extension). A call to
eglStreamConsumerReleaseNV() unlatches the image frame from
the texture.
Any context which is bound to the thread that
eglStreamConsumerAcquireNV and eglStreamConsumerReleaseNV is
called from will "see" the affect of the 'latching' or
'unlatching' immediately. Contexts not bound to that thread
may or may not "see" the effects of latching until the
texture is bound (or re-bound) to the context by calling
glBindTexture.
Changes to section "2.10.4 Shader Variables" of the OpenGL ES 2.0 specification (ignore for OpenGL ES 1.x)
- In the subsection "Uniform Variables" paragraph 13, last sentence, add
"SAMPLER_EXTERNAL_OES"
to the list of types that can be returned.
Changes to section "2.10.5 Shader Execution" of the OpenGL ES 2.0 specification (ignore for OpenGL ES 1.x)
- In the subsection "Validation", add to the bullet points in the second
paragraph:
"- the number of texture image units required is greater than
the number available (see REQUIRED_TEXTURE_IMAGE_UNITS_OES,
MAX_COMBINED_TEXTURE_IMAGE_UNITS, MAX_VERTEX_TEXTURE_IMAGE_UNITS,
and MAX_TEXTURE_IMAGE_UNITS).
- the number of uniforms required to implement the shader program is
greater than the number available."
Changes to section "3.7.5 Texture Parameters" of the OpenGL ES 1.1 specification
- Add to the end of the section a new paragraph:
"When <target> is TEXTURE_EXTERNAL_OES only NEAREST and LINEAR are
accepted as TEXTURE_MIN_FILTER, only CLAMP_TO_EDGE is accepted as
TEXTURE_WRAP_S and TEXTURE_WRAP_T, and only FALSE is accepted as
GENERATE_MIPMAP. Attempting to set other values for
TEXTURE_MIN_FILTER, TEXTURE_WRAP_S, TEXTURE_WRAP_T, or GENERATE_MIPMAP
will result in an INVALID_ENUM error.
Changes to section "3.7.4 Texture Parameters" of the OpenGL ES 2.0 Specification
- Add to the end of the section a new paragraph:
"When <target> is TEXTURE_EXTERNAL_OES only NEAREST and LINEAR are
accepted as TEXTURE_MIN_FILTER and only CLAMP_TO_EDGE is accepted as
TEXTURE_WRAP_S and TEXTURE_WRAP_T. Attempting to set other values for
TEXTURE_MIN_FILTER, TEXTURE_WRAP_S, or TEXTURE_WRAP_T will result in
an INVALID_ENUM error.
Changes to section "3.7.10 Texture State" of the OpenGL ES 1.1 Specification and section "3.7.12 Texture State" of the OpenGL ES 2.0 Specification
- Add an additional sentence at the end of the section:
"In the initial state of a TEXTURE_EXTERNAL_OES texture object,
the value assigned to TEXTURE_MIN_FILTER and TEXTURE_MAG_FILTER is
LINEAR, and the s and t wrap modes are both set to
CLAMP_TO_EDGE."
Changes to section "3.7.11 Mipmap Generation" of the OpenGL ES 2.0 Specification (ignore for OpenGL ES 1.x)
- Add two additional paragraphs to the end of the section:
"When <target> is set to TEXTURE_EXTERNAL_OES, GenerateMipmap
always fails and generates an INVALID_ENUM error."
Changes to section "3.7.11 Texture Objects" of the OpenGL ES 1.1 specification (ignore for OpenGL ES 2.x)
- Modify this section as follows: (changed lines marked with *, and added
lines are marked with +)
- "In addition to the default textures TEXTURE_2D and
-
TEXTURE_EXTERNAL_OES, named two-dimensional and external texture objects can be created and operated upon. The name space for texture objects is the unsigned integers, with zero reserved by the GL.
A texture object is created by binding an unused name to - TEXTURE_2D or TEXTURE_EXTERNAL_OES. The binding is effected by calling void BindTexture( enum target, uint texture );
- with target set to the desired texture target and texture set to the unused name. The resulting texture object is a new state vector, comprising all the state values listed in section 3.7.10, set to the
- same initial values. If the new texture object is bound to TEXTURE_2D
- or TEXTURE_EXTERNAL_OES it is and remains a two-dimensional or
-
external texture respectively until it is deleted.
BindTexture may also be used to bind an existing texture object to -
TEXTURE_2D or TEXTURE_EXTERNAL_OES. If the bind is successful no change is made to the state of the bound texture object, and any previous binding to target is broken.
While a texture object is bound, GL operations on the target to which it is bound affect the bound object, and queries of the target to which it is bound return state from the bound object. If texture mapping is enabled, the state of the bound texture object directs the texturing operation. - In the initial state, TEXTURE_2D and TEXTURE_EXTERNAL_OES have
- two-dimensional and external texture state vectors respectively
- associated with them. In order that access to these initial textures
- not be lost, they are treated as texture objects all of whose names
- are 0. The initial two-dimensional and external texture are therefore
- operated upon, queried, and applied as TEXTURE_2D or
- TEXTURE_EXTERNAL_OES respectively while 0 is bound to the
-
corresponding targets.
Texture objects are deleted by calling void DeleteTextures( sizei n, uint *textures ); textures contains n names of texture objects to be deleted. After a texture object is deleted, it has no contents, and its name is again unused. If a texture that is currently bound to the target TEXTURE_2D -
or TEXTURE_EXTERNAL_OES is deleted, it is as though BindTexture had been executed with the same target and texture zero. Unused names in textures are silently ignored, as is the value zero.
The command void GenTextures( sizei n, uint *textures ); returns n previously unused texture object names in textures. These names are marked as used, for the purposes of GenTextures only, but they acquire texture state only when they are first bound, just as if they were unused. The texture object name space, including the initial texture object, is shared among all texture units. A texture object may be bound to more than one texture unit simultaneously. After a texture object is bound, any GL operations on that target object affect any other texture units to which the same texture object is bound. Texture binding is affected by the setting of the state ACTIVE_TEXTURE. If a texture object is deleted, it is as if all texture units which are bound to that texture object are rebound to texture object zero.
Changes to section "3.7.13 Texture Objects" of the OpenGL ES 2.0 specification (ignore for OpenGL ES 1.x)
- Modify this section as follows: (changed lines marked with *, and added
lines are marked with +)
- "In addition to the default textures TEXTURE_2D, TEXTURE_CUBE_MAP,
-
and TEXTURE_EXTERNAL_OES, named two-dimensional, cube map, and external texture objects can be created and operated upon. The name space for texture objects is the unsigned integers, with zero reserved by the GL.
A texture object is created by binding an unused name to - TEXTURE_2D, TEXTURE_CUBE_MAP, or TEXTURE_EXTERNAL_OES. The binding is effected by calling void BindTexture( enum target, uint texture ); with target set to the desired texture target and texture set to the unused name. The resulting texture object is a new state vector, comprising all the state values listed in section 3.7.12, set to the same initial values. If the new texture object is bound to TEXTURE_2D,
- TEXTURE_CUBE_MAP, or TEXTURE_EXTERNAL_OES it is and remains a
-
two-dimensional, cube map, or external texture respectively until it is deleted.
BindTexture may also be used to bind an existing texture object to - either TEXTURE_2D, TEXTURE_CUBE_MAP, or TEXTURE_EXTERNAL_OES. The error INVALID_OPERATION is generated if an attempt is made to bind a texture
-
object of different target than the specified target. If the bind is successful no change is made to the state of the bound texture object, and any previous binding to target is broken.
While a texture object is bound, GL operations on the target to which it is bound affect the bound object, and queries of the target to which it is bound return state from the bound object. If texture mapping is enabled, the state of the bound texture object directs the texturing operation. - In the initial state, TEXTURE_2D, TEXTURE_CUBE_MAP, and
- TEXTURE_EXTERNAL_OES have two-dimensional, cube map, and external texture state vectors respectively associated with them. In order that access to these initial textures not be lost, they are treated as texture objects all of whose names are 0. The initial two-dimensional,
- cube map, and external texture are therefore operated upon, queried,
-
and applied as TEXTURE_2D, TEXTURE_CUBE_MAP, or TEXTURE_EXTERNAL_OES respectively while 0 is bound to the corresponding targets.
Texture objects are deleted by calling void DeleteTextures( sizei n, uint *textures ); textures contains n names of texture objects to be deleted. After a texture object is deleted, it has no contents or dimensionality, and its name is again unused. If a texture that is currently bound to one -
of the targets TEXTURE_2D, TEXTURE_CUBE_MAP, or TEXTURE_EXTERNAL_OES is deleted, it is as though BindTexture had been executed with the same target and texture zero. Unused names in textures are silently ignored, as is the value zero.
The command void GenTextures( sizei n, uint *textures ); returns n previously unused texture object names in textures. These names are marked as used, for the purposes of GenTextures only, but they acquire texture state only when they are first bound, just as if they were unused. The texture object name space, including the initial texture object, is shared among all texture units. A texture object may be bound to more than one texture unit simultaneously. After a texture object is bound, any GL operations on that target object affect any other texture units to which the same texture object is bound. Texture binding is affected by the setting of the state ACTIVE_TEXTURE. If a texture object is deleted, it is as if all texture units which are bound to that texture object are rebound to texture object zero.
Changes to section "3.7.13 Texture Application" of the OpenGL ES 1.1 specification (ignore for OpenGL ES 2.x)
- Replace the first sentence of the first paragraph with:
"Texturing is enabled or disabled using the generic Enable and
Disable commands, with the symbolic constant TEXTURE_2D or
TEXTURE_EXTERNAL_OES to enable or disable texturing with the
TEXTURE_2D or TEXTURE_EXTERNAL_OES texture target, respectively. If
TEXTURE_EXTERNAL_OES is enabled it takes precedence over TEXTURE_2D,
TEXTURE_CUBE_MAP_OES, TEXTURE_RECTANGLE_ARB, and
TEXTURE_RECTANGLE_NV."
Changes to section "3.8.2 Shader Execution" of the OpenGL ES 2.0 specification (ignore for OpenGL ES 1.x)
- Add to the end of the last paragraph of the subsection "Texture Access"
"The REQUIRED_TEXTURE_IMAGE_UNITS_OES parameter can change based on the
number of external textures which are currently bound (see section
3.7.14)."
Changes to section "6.1.3 Enumerated Queries" of the OpenGL ES 1.1 specification
- Change:
"...TEXTURE_2D..."
to
"...TEXTURE_2D or TEXTURE_EXTERNAL..."
in the last paragraph.
Changes to section "6.1.3 Enumerated Queries" of the OpenGL ES 2.0 specification
- Change:
"...TEXTURE_2D or TEXTURE_CUBE_MAP..."
to
"...TEXTURE_2D, TEXTURE_CUBE_MAP, or TEXTURE_EXTERNAL..."
in the second paragraph.
Changes to section "6.2 State Tables" of the OpenGL ES 1.1 specification
- Add to "Table 6.13 Textures (state per texture unit and binding point)"
+-------------------+-------+-------------+-------+------------------+
| TEXTURE_BINDING_- | 8*xZ+ | GetIntegerv | 0 | Texture object |
| EXTERNAL_OES | | | | bound to |
| | | | | TEXTURE_- |
| | | | | EXTERNAL_OES |
+-------------------+-------+-------------+-------+------------------+
| TEXTURE_- | 2*xB | IsEnabled | False | True if external |
| EXTERNAL_OES | | | | texturing is |
| | | | | enabled |
+-------------------+-------+-------------+---+----------------------+
- Add to "Table 6.14 Textures (state per texture object)"
+--------------------+-------+-----------------+---+----------------+
| REQUIRED_TEXTURE_- | n*xZ3 | GetTexParameter | 1 | Number of |
| IMAGE_UNITS_OES | | | | texture image |
| | | | | units required |
| | | | | by texture |
+--------------------+-------+-----------------+---+----------------+
Changes to section "6.2 State Tables" of the OpenGL ES 2.0 specification
- Add to "Table 6.7 Textures (state per texture unit and binding point)"
+-------------------+-------+-------------+-------+------------------+
| TEXTURE_BINDING_- | 8*xZ+ | GetIntegerv | 0 | Texture object |
| EXTERNAL_OES | | | | bound to |
| | | | | TEXTURE_- |
| | | | | EXTERNAL_OES |
+-------------------+-------+-------------+-------+------------------+
- Add to "Table 6.8 Textures (state per texture object)"
+--------------------+-------+-----------------+---+----------------+
| REQUIRED_TEXTURE_- | n*xZ3 | GetTexParameter | 1 | Number of |
| IMAGE_UNITS_OES | | | | texture image |
| | | | | units required |
| | | | | by texture |
+--------------------+-------+-----------------+---+----------------+
Changes to section 3.7 of the OpenGL ES Shading Language specification
- Add to the list of keywords:
"samplerExternalOES"
Changes to section 4.1 of the OpenGL ES Shading Language specification
- Add to the list of basic types:
"samplerExternalOES a handle for accessing an external texture"
Changes to section 4.5.3 of the OpenGL ES Shading Language specification
- Add to the list of "vertex language has the following predeclared
globally scoped default precision statements:"
"precision lowp samplerExternalOES;"
- Add to the list of "fragment language has the following predeclared
globally scoped default precision statements:"
"precision lowp samplerExternalOES;"
Changes to section 8.7 of the OpenGL ES Shading Language specification
- Add to the table the following sampler functions:
"vec4 texture2D(
samplerExternalOES sampler,
vec2 coord)
vec4 texture2DProj(
samplerExternalOES sampler,
vec3 coord)
vec4 texture2DProj(
samplerExternalOES sampler,
vec4 coord)"
Changes to section 9 of the OpenGL ES Shading Language specification
- Add to token list:
"SAMPLEREXTERNAL"
- Add following "type_specifier_no_prec:"
"SAMPLEREXTERNAL"
Changes to section "A.7 Counting of Varyings and Uniforms" of the OpenGL ES Shading Language specification
- Change the first sentence of the last paragraph to
"Part of the storage may be reserved by an implementation for its own
use e.g. for computation of transcendental functions or conversion of
external textures."
Issues
In addition to issues below, see issues from the
GL_OES_EGL_image_external extension.
1. Is this extension needed, or is the
EGL_NV_stream_consumer_gltexture extension plus the existing
GL_OES_EGL_image_external extension enough to cover this?
SUGGESTION: yes
DISCUSSION: The EGL_NV_stream_consumer_gltexture and
GL_OES_EGL_image_external extensions together define all the
types, tokens, and entry points needed to expose this
functionality. The GL_OES_EGL_image_external extension fully
describes how external textures work. The
EGL_NV_stream_consumer_gltexture extension fully describes how
to associate an EGLStream with an external texture.
However, there were questions about exactly how it was
supposed to work. This extension clarifies some of those
questions.
Also, this allows the GL driver to expose the extension
independent of the EGL driver. This might be important in
situations where 2 GLES drivers exist on the same system, one
of which supports this functionality and the other not.
2. Should this be an NV, EXT, or OES extension?
It was originally drafted as OES, but then quickly changed to
NV as the policy in the ES group is to not draft extensions
as OES until they are ratified. The assumption is that this
will be an OES if the ES group agrees with it, or possibly an
EXT otherwise. For now, while it is a draft, it will be NV.
3. Why are the new enumerants suffixed with _OES if this is an NV
extension?
SUGGESTION: These enumerants are all already added (with _OES
suffixes) by the GL_OES_EGL_image_external extension. Adding
the same enums with NV suffix would be confusing.
Dependencies on OES_EGL_image_external.
This extension builds on the ideas of the OES_EGL_image_external
extension. If both are supported then this extension adds
language to that extension. If this extension is supported
without that one then some parts of that extension get included by
this extension. This is mentioned inline in this extension. Some
of the sections added by this extension are verbatim copies from
that extension. If both are supported these sections should only
be added once.
Dependencies on EGL_KHR_image_base and EGL_KHR_image
This extension neither depends on nor affects the wording of
EGL_KHR_image_base or EGL_KHR_image. This extension borrows ideas
from the EGLImage related extensions, but does not require them.
Revision History
#3 - (July 19, 2012) Acorn Pooley
Fix name used with #extension in glsl.
#2 - (Aug 3, 2011) Acorn Pooley
Rename from GL_OES_EGL_stream_consumer_external to
GL_NV_EGL_stream_consumer_external
#1 - (Aug 2, 2011) Acorn Pooley
Original draft