extensions/EXT/EXT_map_buffer_range.txt - external/github.com/KhronosGroup/OpenGL-Registry - Git at Google

 Name

     EXT_map_buffer_range

 Name Strings

     GL_EXT_map_buffer_range

 Contributors

     Contributors to ARB_map_buffer_range desktop OpenGL extension from which
     this extension borrows heavily

 Contact

     Benj Lipchak (lipchak 'at' apple 'dot' com)

 Status

     Complete

 Version

     Last Modified Date: August 21, 2014
     Author Revision: 4

 Number

     OpenGL ES Extension #121

 Dependencies

     OpenGL ES 1.1 or OpenGL ES 2.0 is required.

     OES_mapbuffer is required.

     This specification is written against the OpenGL ES 2.0.25 specification.

 Overview

     EXT_map_buffer_range expands the buffer object API to allow greater
     performance when a client application only needs to write to a sub-range
     of a buffer object. To that end, this extension introduces two new buffer
     object features: non-serialized buffer modification and explicit sub-range
     flushing for mapped buffer objects.

     OpenGL requires that commands occur in a FIFO manner meaning that any
     changes to buffer objects either block until the data has been processed by
     the OpenGL pipeline or else create extra copies to avoid such a block.  By
     providing a method to asynchronously modify buffer object data, an
     application is then able to manage the synchronization points themselves
     and modify ranges of data contained by a buffer object even though OpenGL
     might still be using other parts of it.

     This extension also provides a method for explicitly flushing ranges of a
     mapped buffer object so OpenGL does not have to assume that the entire
     range may have been modified.  Further, it allows the application to more
     precisely specify its intent with respect to reading, writing, and whether
     the previous contents of a mapped range of interest need be preserved
     prior to modification.

 New Procedures and Functions

     void *MapBufferRangeEXT(enum target, intptr offset, sizeiptr length,
         bitfield access);

     void FlushMappedBufferRangeEXT(enum target, intptr offset,
         sizeiptr length);


 New Tokens

     Accepted by the <access> parameter of MapBufferRangeEXT:

     MAP_READ_BIT_EXT                  0x0001
     MAP_WRITE_BIT_EXT                 0x0002
     MAP_INVALIDATE_RANGE_BIT_EXT      0x0004
     MAP_INVALIDATE_BUFFER_BIT_EXT     0x0008
     MAP_FLUSH_EXPLICIT_BIT_EXT        0x0010
     MAP_UNSYNCHRONIZED_BIT_EXT        0x0020


 Additions to Chapter 2 of the OpenGL ES 2.0 Specification (OpenGL ES Operation)

     Add to the end of Section 2.9 "Buffer Objects" (p. 24):

     All or part of the data store of a buffer object may be mapped into the
     client's address space by calling

     void *MapBufferRangeEXT(enum target, intptr offset, sizeiptr length,
         bitfield access);

     with <target> set to ARRAY_BUFFER or ELEMENT_ARRAY_BUFFER.
     <offset> and <length> indicate the range of data in the
     buffer object that is to be mapped, in terms of basic machine units.
     <access> is a bitfield containing flags which describe the requested
     mapping. These flags are described below.

     If no error occurs, a pointer to the beginning of the mapped range is
     returned once all pending operations on that buffer have completed, and
     may be used to modify and/or query the corresponding range of the buffer,
     according to the following flag bits set in <access>:

     * MAP_READ_BIT_EXT indicates that the returned pointer may be used to
     read buffer object data. No GL error is generated if the pointer is used
     to query a mapping which excludes this flag, but the result is undefined
     and system errors (possibly including program termination) may occur.

     * MAP_WRITE_BIT_EXT indicates that the returned pointer may be used to
     modify buffer object data. No GL error is generated if the pointer is used
     to modify a mapping which excludes this flag, but the result is undefined
     and system errors (possibly including program termination) may occur.

     Pointer values returned by MapBufferRangeEXT may not be passed as
     parameter values to GL commands. For example, they may not be used to
     specify array pointers, or to specify or query pixel or texture image
     data; such actions produce undefined results, although implementations
     may not check for such behavior for performance reasons.

     Mappings to the data stores of buffer objects may have nonstandard
     performance characteristics. For example, such mappings may be marked as
     uncacheable regions of memory, and in such cases reading from them may be
     very slow. To ensure optimal performance, the client should use the
     mapping in a fashion consistent with the values of BUFFER_USAGE and
     <access>. Using a mapping in a fashion inconsistent with these values is
     liable to be multiple orders of magnitude slower than using normal memory.

     The following optional flag bits in <access> may be used to modify the
     mapping:

     * MAP_INVALIDATE_RANGE_BIT_EXT indicates that the previous contents of
     the specified range may be discarded. Data within this range are undefined
     with the exception of subsequently written data. No GL error is generated
     if subsequent GL operations access unwritten data, but the result is
     undefined and system errors (possibly including program termination) may
     occur. This flag may not be used in combination with MAP_READ_BIT_EXT.

     * MAP_INVALIDATE_BUFFER_BIT_EXT indicates that the previous contents of
     the entire buffer may be discarded. Data within the entire buffer are
     undefined with the exception of subsequently written data. No GL error is
     generated if subsequent GL operations access unwritten data, but the
     result is undefined and system errors (possibly including program
     termination) may occur. This flag may not be used in combination with
     MAP_READ_BIT_EXT.

     * MAP_FLUSH_EXPLICIT_BIT_EXT indicates that one or more discrete
     subranges of the mapping may be modified. When this flag is set,
     modifications to each subrange must be explicitly flushed by calling
     FlushMappedBufferRangeEXT. No GL error is set if a subrange of the
     mapping is modified and not flushed, but data within the corresponding
     subrange of the buffer is undefined. This flag may only be used in
     conjunction with MAP_WRITE_BIT_EXT. When this option is selected,
     flushing is strictly limited to regions that are explicitly indicated
     with calls to FlushMappedBufferRangeEXT prior to unmap; if this
     option is not selected UnmapBufferOES will automatically flush the entire
     mapped range when called.

     * MAP_UNSYNCHRONIZED_BIT_EXT indicates that the GL should not attempt
     to synchronize pending operations on the buffer prior to returning from
     MapBufferRangeEXT. No GL error is generated if pending operations which
     source or modify the buffer overlap the mapped region, but the result of
     such previous and any subsequent operations is undefined.

     A successful MapBufferRangeEXT sets buffer object state values as shown
     in table 2.mbr.

     Name                 Value
     -------------------  -----
     BUFFER_ACCESS_FLAGS  <access>
     BUFFER_MAPPED        TRUE
     BUFFER_MAP_POINTER   pointer to the data store
     BUFFER_MAP_OFFSET    <offset>
     BUFFER_MAP_LENGTH    <length>

     Table 2.mbr: Buffer object state set by MapBufferRangeEXT.

     If an error occurs, MapBufferRangeEXT returns a NULL pointer.

     An INVALID_VALUE error is generated if <offset> or <length> is negative,
     if <offset> + <length> is greater than the value of BUFFER_SIZE, or if
     <access> has any bits set other than those defined above.

     An INVALID_OPERATION error is generated for any of the following
     conditions:

     * <length> is zero.
     * The buffer is already in a mapped state.
     * Neither MAP_READ_BIT_EXT nor MAP_WRITE_BIT_EXT is set.
     * MAP_READ_BIT_EXT is set and any of MAP_INVALIDATE_RANGE_BIT_EXT,
       MAP_INVALIDATE_BUFFER_BIT_EXT, or MAP_UNSYNCHRONIZED_BIT_EXT is set.
     * MAP_FLUSH_EXPLICIT_BIT_EXT is set and MAP_WRITE_BIT_EXT is not set.

     An OUT_OF_MEMORY error is generated if MapBufferRangeEXT fails because
     memory for the mapping could not be obtained.

     No error is generated if memory outside the mapped range is modified or
     queried, but the result is undefined and system errors (possibly including
     program termination) may occur.

     If a buffer is mapped with the MAP_FLUSH_EXPLICIT_BIT_EXT flag,
     modifications to the mapped range may be indicated by calling

     void FlushMappedBufferRangeEXT(enum target, intptr offset,
         sizeiptr length);

     with <target> set to ARRAY_BUFFER or ELEMENT_ARRAY_BUFFER. <offset> and
     <length> indicate a modified subrange of the mapping, in basic machine
     units. The specified subrange to flush is relative to the start of the
     currently mapped range of buffer. FlushMappedBufferRangeEXT may be
     called multiple times to indicate distinct subranges of the mapping which
     require flushing.

     An INVALID_VALUE error is generated if <offset> or <length> is negative,
     or if <offset> + <length> exceeds the size of the mapping.

     An INVALID_OPERATION error is generated if zero is bound to <target>.

     An INVALID_OPERATION error is generated if the buffer bound to <target>
     is not mapped, or is mapped without the MAP_FLUSH_EXPLICIT_BIT_EXT flag.

 New Implementation Dependent State

     None

 Usage Examples

     /* bind and initialize a buffer object */
     int size = 65536;
     glBindBuffer(GL_ARRAY_BUFFER, 1);
     glBufferData(GL_ARRAY_BUFFER, size, NULL, GL_DYNAMIC_DRAW);

 /* the following are not meant to be executed as a group, since there are no
  * unmap calls shown here - they are meant to show different combinations of
  * map options in conjunction with MapBufferRangeEXT and
  * FlushMappedBufferRangeEXT.
  */

     /* Map the entire buffer with read and write
      * (identical semantics to MapBufferOES).
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, size,
         MAP_READ_BIT_EXT | MAP_WRITE_BIT_EXT);

     /* Map the entire buffer as write only.
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, size,
         MAP_WRITE_BIT_EXT);


     /* Map the last 1K bytes of the buffer as write only.
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, size-1024, 1024,
         MAP_WRITE_BIT_EXT);


     /* Map the last 1K bytes of the buffer as write only, and invalidate the
      * range. Locations within that range can assume undefined values.
      * Locations written while mapped take on new values as expected.
      * No changes occur outside the range mapped.
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, size-1024, 1024,
         MAP_WRITE_BIT_EXT | MAP_INVALIDATE_RANGE_BIT_EXT);


     /* Map the first 1K bytes of the buffer as write only, and invalidate the
      * entire buffer. All locations within the buffer can assume undefined
      * values. Locations written while mapped take on new values as expected.
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, 1024,
         MAP_WRITE_BIT_EXT | MAP_INVALIDATE_BUFFER_BIT_EXT);


     /* Map the first 32K bytes of the buffer as write only, and invalidate
      * that range. Indicate that we will explicitly inform GL which ranges are
      * actually written. Locations within that range can assume undefined
      * values. Only the locations which are written and subsequently flushed
      * are guaranteed to take on defined values.
      * Write data to the first 8KB of the range, then flush it.
      * Write data to the last 8KB of the range, then flush it.
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, 32768,
         MAP_WRITE_BIT_EXT | MAP_INVALIDATE_RANGE_BIT_EXT |
         MAP_FLUSH_EXPLICIT_BIT_EXT);

     memset(ptr, 0x00, 8192);           /* write zeroes to first 8KB of range */
     glFlushMappedBufferRangeEXT(GL_ARRAY_BUFFER, 0, 8192);

     memset(((char*)ptr)+24576, 0xFF, 8192);/* write FFs to last 8KB of range */
     glFlushMappedBufferRangeEXT(GL_ARRAY_BUFFER, 24576, 8192);


     /* Map the entire buffer for write - unsynchronized.
      * GL will not block for prior operations to complete.  Application must
      * use other synchronization techniques to ensure correct operation.
      */
     void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, size,
         MAP_WRITE_BIT_EXT | MAP_UNSYNCHRONIZED_BIT_EXT);


 Revision History

     Version 4, 2014/08/21 - Fix typo OES_map_buffer -> OES_mapbuffer.
     Version 3, 2012/06/21 - Recast from APPLE to multivendor EXT
     Version 2, 2012/06/18 - Correct spec to indicate ES 1.1 may also be okay.
     Version 1, 2012/06/01 - Conversion from ARB_map_buffer_range to
                             APPLE_map_buffer_range for ES.
	Name

	EXT_map_buffer_range

	Name Strings

	GL_EXT_map_buffer_range

	Contributors

	Contributors to ARB_map_buffer_range desktop OpenGL extension from which
	this extension borrows heavily

	Contact

	Benj Lipchak (lipchak 'at' apple 'dot' com)

	Status

	Complete

	Version

	Last Modified Date: August 21, 2014
	Author Revision: 4

	Number

	OpenGL ES Extension #121

	Dependencies

	OpenGL ES 1.1 or OpenGL ES 2.0 is required.

	OES_mapbuffer is required.

	This specification is written against the OpenGL ES 2.0.25 specification.

	Overview

	EXT_map_buffer_range expands the buffer object API to allow greater
	performance when a client application only needs to write to a sub-range
	of a buffer object. To that end, this extension introduces two new buffer
	object features: non-serialized buffer modification and explicit sub-range
	flushing for mapped buffer objects.

	OpenGL requires that commands occur in a FIFO manner meaning that any
	changes to buffer objects either block until the data has been processed by
	the OpenGL pipeline or else create extra copies to avoid such a block. By
	providing a method to asynchronously modify buffer object data, an
	application is then able to manage the synchronization points themselves
	and modify ranges of data contained by a buffer object even though OpenGL
	might still be using other parts of it.

	This extension also provides a method for explicitly flushing ranges of a
	mapped buffer object so OpenGL does not have to assume that the entire
	range may have been modified. Further, it allows the application to more
	precisely specify its intent with respect to reading, writing, and whether
	the previous contents of a mapped range of interest need be preserved
	prior to modification.

	New Procedures and Functions

	void *MapBufferRangeEXT(enum target, intptr offset, sizeiptr length,
	bitfield access);

	void FlushMappedBufferRangeEXT(enum target, intptr offset,
	sizeiptr length);


	New Tokens

	Accepted by the <access> parameter of MapBufferRangeEXT:

	MAP_READ_BIT_EXT 0x0001
	MAP_WRITE_BIT_EXT 0x0002
	MAP_INVALIDATE_RANGE_BIT_EXT 0x0004
	MAP_INVALIDATE_BUFFER_BIT_EXT 0x0008
	MAP_FLUSH_EXPLICIT_BIT_EXT 0x0010
	MAP_UNSYNCHRONIZED_BIT_EXT 0x0020


	Additions to Chapter 2 of the OpenGL ES 2.0 Specification (OpenGL ES Operation)

	Add to the end of Section 2.9 "Buffer Objects" (p. 24):

	All or part of the data store of a buffer object may be mapped into the
	client's address space by calling

	void *MapBufferRangeEXT(enum target, intptr offset, sizeiptr length,
	bitfield access);

	with <target> set to ARRAY_BUFFER or ELEMENT_ARRAY_BUFFER.
	<offset> and <length> indicate the range of data in the
	buffer object that is to be mapped, in terms of basic machine units.
	<access> is a bitfield containing flags which describe the requested
	mapping. These flags are described below.

	If no error occurs, a pointer to the beginning of the mapped range is
	returned once all pending operations on that buffer have completed, and
	may be used to modify and/or query the corresponding range of the buffer,
	according to the following flag bits set in <access>:

	* MAP_READ_BIT_EXT indicates that the returned pointer may be used to
	read buffer object data. No GL error is generated if the pointer is used
	to query a mapping which excludes this flag, but the result is undefined
	and system errors (possibly including program termination) may occur.

	* MAP_WRITE_BIT_EXT indicates that the returned pointer may be used to
	modify buffer object data. No GL error is generated if the pointer is used
	to modify a mapping which excludes this flag, but the result is undefined
	and system errors (possibly including program termination) may occur.

	Pointer values returned by MapBufferRangeEXT may not be passed as
	parameter values to GL commands. For example, they may not be used to
	specify array pointers, or to specify or query pixel or texture image
	data; such actions produce undefined results, although implementations
	may not check for such behavior for performance reasons.

	Mappings to the data stores of buffer objects may have nonstandard
	performance characteristics. For example, such mappings may be marked as
	uncacheable regions of memory, and in such cases reading from them may be
	very slow. To ensure optimal performance, the client should use the
	mapping in a fashion consistent with the values of BUFFER_USAGE and
	<access>. Using a mapping in a fashion inconsistent with these values is
	liable to be multiple orders of magnitude slower than using normal memory.

	The following optional flag bits in <access> may be used to modify the
	mapping:

	* MAP_INVALIDATE_RANGE_BIT_EXT indicates that the previous contents of
	the specified range may be discarded. Data within this range are undefined
	with the exception of subsequently written data. No GL error is generated
	if subsequent GL operations access unwritten data, but the result is
	undefined and system errors (possibly including program termination) may
	occur. This flag may not be used in combination with MAP_READ_BIT_EXT.

	* MAP_INVALIDATE_BUFFER_BIT_EXT indicates that the previous contents of
	the entire buffer may be discarded. Data within the entire buffer are
	undefined with the exception of subsequently written data. No GL error is
	generated if subsequent GL operations access unwritten data, but the
	result is undefined and system errors (possibly including program
	termination) may occur. This flag may not be used in combination with
	MAP_READ_BIT_EXT.

	* MAP_FLUSH_EXPLICIT_BIT_EXT indicates that one or more discrete
	subranges of the mapping may be modified. When this flag is set,
	modifications to each subrange must be explicitly flushed by calling
	FlushMappedBufferRangeEXT. No GL error is set if a subrange of the
	mapping is modified and not flushed, but data within the corresponding
	subrange of the buffer is undefined. This flag may only be used in
	conjunction with MAP_WRITE_BIT_EXT. When this option is selected,
	flushing is strictly limited to regions that are explicitly indicated
	with calls to FlushMappedBufferRangeEXT prior to unmap; if this
	option is not selected UnmapBufferOES will automatically flush the entire
	mapped range when called.

	* MAP_UNSYNCHRONIZED_BIT_EXT indicates that the GL should not attempt
	to synchronize pending operations on the buffer prior to returning from
	MapBufferRangeEXT. No GL error is generated if pending operations which
	source or modify the buffer overlap the mapped region, but the result of
	such previous and any subsequent operations is undefined.

	A successful MapBufferRangeEXT sets buffer object state values as shown
	in table 2.mbr.

	Name Value
	------------------- -----
	BUFFER_ACCESS_FLAGS <access>
	BUFFER_MAPPED TRUE
	BUFFER_MAP_POINTER pointer to the data store
	BUFFER_MAP_OFFSET <offset>
	BUFFER_MAP_LENGTH <length>

	Table 2.mbr: Buffer object state set by MapBufferRangeEXT.

	If an error occurs, MapBufferRangeEXT returns a NULL pointer.

	An INVALID_VALUE error is generated if <offset> or <length> is negative,
	if <offset> + <length> is greater than the value of BUFFER_SIZE, or if
	<access> has any bits set other than those defined above.

	An INVALID_OPERATION error is generated for any of the following
	conditions:

	* <length> is zero.
	* The buffer is already in a mapped state.
	* Neither MAP_READ_BIT_EXT nor MAP_WRITE_BIT_EXT is set.
	* MAP_READ_BIT_EXT is set and any of MAP_INVALIDATE_RANGE_BIT_EXT,
	MAP_INVALIDATE_BUFFER_BIT_EXT, or MAP_UNSYNCHRONIZED_BIT_EXT is set.
	* MAP_FLUSH_EXPLICIT_BIT_EXT is set and MAP_WRITE_BIT_EXT is not set.

	An OUT_OF_MEMORY error is generated if MapBufferRangeEXT fails because
	memory for the mapping could not be obtained.

	No error is generated if memory outside the mapped range is modified or
	queried, but the result is undefined and system errors (possibly including
	program termination) may occur.

	If a buffer is mapped with the MAP_FLUSH_EXPLICIT_BIT_EXT flag,
	modifications to the mapped range may be indicated by calling

	void FlushMappedBufferRangeEXT(enum target, intptr offset,
	sizeiptr length);

	with <target> set to ARRAY_BUFFER or ELEMENT_ARRAY_BUFFER. <offset> and
	<length> indicate a modified subrange of the mapping, in basic machine
	units. The specified subrange to flush is relative to the start of the
	currently mapped range of buffer. FlushMappedBufferRangeEXT may be
	called multiple times to indicate distinct subranges of the mapping which
	require flushing.

	An INVALID_VALUE error is generated if <offset> or <length> is negative,
	or if <offset> + <length> exceeds the size of the mapping.

	An INVALID_OPERATION error is generated if zero is bound to <target>.

	An INVALID_OPERATION error is generated if the buffer bound to <target>
	is not mapped, or is mapped without the MAP_FLUSH_EXPLICIT_BIT_EXT flag.

	New Implementation Dependent State

	None

	Usage Examples

	/* bind and initialize a buffer object */
	int size = 65536;
	glBindBuffer(GL_ARRAY_BUFFER, 1);
	glBufferData(GL_ARRAY_BUFFER, size, NULL, GL_DYNAMIC_DRAW);

	/* the following are not meant to be executed as a group, since there are no
	* unmap calls shown here - they are meant to show different combinations of
	* map options in conjunction with MapBufferRangeEXT and
	* FlushMappedBufferRangeEXT.
	*/

	/* Map the entire buffer with read and write
	* (identical semantics to MapBufferOES).
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, size,
	MAP_READ_BIT_EXT \| MAP_WRITE_BIT_EXT);

	/* Map the entire buffer as write only.
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, size,
	MAP_WRITE_BIT_EXT);


	/* Map the last 1K bytes of the buffer as write only.
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, size-1024, 1024,
	MAP_WRITE_BIT_EXT);


	/* Map the last 1K bytes of the buffer as write only, and invalidate the
	* range. Locations within that range can assume undefined values.
	* Locations written while mapped take on new values as expected.
	* No changes occur outside the range mapped.
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, size-1024, 1024,
	MAP_WRITE_BIT_EXT \| MAP_INVALIDATE_RANGE_BIT_EXT);


	/* Map the first 1K bytes of the buffer as write only, and invalidate the
	* entire buffer. All locations within the buffer can assume undefined
	* values. Locations written while mapped take on new values as expected.
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, 1024,
	MAP_WRITE_BIT_EXT \| MAP_INVALIDATE_BUFFER_BIT_EXT);


	/* Map the first 32K bytes of the buffer as write only, and invalidate
	* that range. Indicate that we will explicitly inform GL which ranges are
	* actually written. Locations within that range can assume undefined
	* values. Only the locations which are written and subsequently flushed
	* are guaranteed to take on defined values.
	* Write data to the first 8KB of the range, then flush it.
	* Write data to the last 8KB of the range, then flush it.
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, 32768,
	MAP_WRITE_BIT_EXT \| MAP_INVALIDATE_RANGE_BIT_EXT \|
	MAP_FLUSH_EXPLICIT_BIT_EXT);

	memset(ptr, 0x00, 8192); /* write zeroes to first 8KB of range */
	glFlushMappedBufferRangeEXT(GL_ARRAY_BUFFER, 0, 8192);

	memset(((char)ptr)+24576, 0xFF, 8192);/ write FFs to last 8KB of range */
	glFlushMappedBufferRangeEXT(GL_ARRAY_BUFFER, 24576, 8192);


	/* Map the entire buffer for write - unsynchronized.
	* GL will not block for prior operations to complete. Application must
	* use other synchronization techniques to ensure correct operation.
	*/
	void *ptr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, size,
	MAP_WRITE_BIT_EXT \| MAP_UNSYNCHRONIZED_BIT_EXT);


	Revision History

	Version 4, 2014/08/21 - Fix typo OES_map_buffer -> OES_mapbuffer.
	Version 3, 2012/06/21 - Recast from APPLE to multivendor EXT
	Version 2, 2012/06/18 - Correct spec to indicate ES 1.1 may also be okay.
	Version 1, 2012/06/01 - Conversion from ARB_map_buffer_range to
	APPLE_map_buffer_range for ES.