Class KHRRobustness
Several recent trends in how OpenGL ES integrates into modern computer systems have created new requirements for robustness and security for GL rendering contexts.
Additionally GPU architectures now support hardware fault detection; for example, video memory supporting ECC (error correcting codes) and error detection. GL contexts should be capable of recovering from hardware faults such as uncorrectable memory errors. Along with recovery from such hardware faults, the recovery mechanism can also allow recovery from video memory access exceptions and system software failures. System software failures can be due to device changes or driver failures.
GL queries that return (write) some number of bytes to a buffer indicated by a pointer parameter introduce risk of buffer overflows that might be exploitable by malware. To address this, queries with return value sizes that are not expressed directly by the parameters to the query itself are given additional API functions with an additional parameter that specifies the number of bytes in the buffer and never writing bytes beyond that limit. This is particularly useful for multi-threaded usage of GL contexts in a "share group" where one context can change objects in ways that can cause buffer overflows for another context's GL queries.
The original ARB_vertex_buffer_object extension includes an issue that explicitly states program termination is allowed when out-of-bounds vertex buffer object fetches occur. Modern graphics hardware is capable of well-defined behavior in the case of out-of- bounds vertex buffer object fetches. Older hardware may require extra checks to enforce well-defined (and termination free) behavior, but this expense is warranted when processing potentially untrusted content.
The intent of this extension is to address some specific robustness goals:
- For all existing GL queries, provide additional "safe" APIs that limit data written to user pointers to a buffer size in bytes that is an explicit additional parameter of the query.
- Provide a mechanism for a GL application to learn about graphics resets that affect the context. When a graphics reset occurs, the GL context becomes unusable and the application must create a new context to continue operation. Detecting a graphics reset happens through an inexpensive query.
- Define behavior of OpenGL calls made after a graphics reset.
- Provide an enable to guarantee that out-of-bounds buffer object accesses by the GPU will have deterministic behavior and preclude application instability or termination due to an incorrect buffer access. Such accesses include vertex buffer fetches of attributes and indices, and indexed reads of uniforms or parameters from buffers.
Requires OpenGL 3.2
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Field Summary
Modifier and TypeFieldDescriptionstatic final int
Returned byGetError
.static final int
Accepted by thevalue
parameter of GetBooleanv, GetIntegerv, and GetFloatv.static final int
Returned byGetGraphicsResetStatus
.static final int
Returned byGetGraphicsResetStatus
.static final int
Returned by GetIntegerv and related simple queries whenvalue
isRESET_NOTIFICATION_STRATEGY
.static final int
Returned byGetGraphicsResetStatus
.static final int
Returned by GetIntegerv and related simple queries whenvalue
isRESET_NOTIFICATION_STRATEGY
.static final int
Accepted by thevalue
parameter of GetBooleanv, GetIntegerv, and GetFloatv.static final int
Returned byGetGraphicsResetStatus
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Method Summary
Modifier and TypeMethodDescriptionstatic int
Indicates if the GL context has been in a reset state at any point since the last call to GetGraphicsResetStatus:NO_ERROR
indicates that the GL context has not been in a reset state since the last call.GUILTY_CONTEXT_RESET
indicates that a reset has been detected that is attributable to the current GL context.INNOCENT_CONTEXT_RESET
indicates a reset has been detected that is not attributable to the current GL context.UNKNOWN_CONTEXT_RESET
indicates a detected graphics reset whose cause is unknown.static float
glGetnUniformf
(int program, int location) Returns the value or values of a uniform of the default uniform block.static void
glGetnUniformfv
(int program, int location, float[] params) Array version of:GetnUniformfv
static void
glGetnUniformfv
(int program, int location, FloatBuffer params) Returns the value or values of a uniform of the default uniform block.static int
glGetnUniformi
(int program, int location) Integer version ofGetnUniformfv
.static void
glGetnUniformiv
(int program, int location, int[] params) Array version of:GetnUniformiv
static void
glGetnUniformiv
(int program, int location, IntBuffer params) Integer version ofGetnUniformfv
.static int
glGetnUniformui
(int program, int location) Unsigned version ofGetnUniformiv
.static void
glGetnUniformuiv
(int program, int location, int[] params) Array version of:GetnUniformuiv
static void
glGetnUniformuiv
(int program, int location, IntBuffer params) Unsigned version ofGetnUniformiv
.static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, float[] pixels) Array version of:ReadnPixels
static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, int[] pixels) Array version of:ReadnPixels
static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, int bufSize, long pixels) static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, short[] pixels) Array version of:ReadnPixels
static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, ByteBuffer pixels) static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, FloatBuffer pixels) static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, IntBuffer pixels) static void
glReadnPixels
(int x, int y, int width, int height, int format, int type, ShortBuffer pixels) static void
nglGetnUniformfv
(int program, int location, int bufSize, long params) Unsafe version of:GetnUniformfv
static void
nglGetnUniformiv
(int program, int location, int bufSize, long params) Unsafe version of:GetnUniformiv
static void
nglGetnUniformuiv
(int program, int location, int bufSize, long params) Unsafe version of:GetnUniformuiv
static void
nglReadnPixels
(int x, int y, int width, int height, int format, int type, int bufSize, long pixels) Unsafe version of:ReadnPixels
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Field Details
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GL_NO_ERROR
public static final int GL_NO_ERRORReturned byGetGraphicsResetStatus
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GL_GUILTY_CONTEXT_RESET
public static final int GL_GUILTY_CONTEXT_RESETReturned byGetGraphicsResetStatus
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GL_INNOCENT_CONTEXT_RESET
public static final int GL_INNOCENT_CONTEXT_RESETReturned byGetGraphicsResetStatus
.- See Also:
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GL_UNKNOWN_CONTEXT_RESET
public static final int GL_UNKNOWN_CONTEXT_RESETReturned byGetGraphicsResetStatus
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GL_CONTEXT_ROBUST_ACCESS
public static final int GL_CONTEXT_ROBUST_ACCESSAccepted by thevalue
parameter of GetBooleanv, GetIntegerv, and GetFloatv.- See Also:
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GL_RESET_NOTIFICATION_STRATEGY
public static final int GL_RESET_NOTIFICATION_STRATEGYAccepted by thevalue
parameter of GetBooleanv, GetIntegerv, and GetFloatv.- See Also:
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GL_LOSE_CONTEXT_ON_RESET
public static final int GL_LOSE_CONTEXT_ON_RESETReturned by GetIntegerv and related simple queries whenvalue
isRESET_NOTIFICATION_STRATEGY
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GL_NO_RESET_NOTIFICATION
public static final int GL_NO_RESET_NOTIFICATIONReturned by GetIntegerv and related simple queries whenvalue
isRESET_NOTIFICATION_STRATEGY
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GL_CONTEXT_LOST
public static final int GL_CONTEXT_LOSTReturned byGetError
.- See Also:
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Method Details
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glGetGraphicsResetStatus
public static int glGetGraphicsResetStatus()Indicates if the GL context has been in a reset state at any point since the last call to GetGraphicsResetStatus:NO_ERROR
indicates that the GL context has not been in a reset state since the last call.GUILTY_CONTEXT_RESET
indicates that a reset has been detected that is attributable to the current GL context.INNOCENT_CONTEXT_RESET
indicates a reset has been detected that is not attributable to the current GL context.UNKNOWN_CONTEXT_RESET
indicates a detected graphics reset whose cause is unknown.
If a reset status other than NO_ERROR is returned and subsequent calls return NO_ERROR, the context reset was encountered and completed. If a reset status is repeatedly returned, the context may be in the process of resetting.
Reset notification behavior is determined at context creation time, and may be queried by calling GetIntegerv with the symbolic constant
RESET_NOTIFICATION_STRATEGY
.If the reset notification behavior is
NO_RESET_NOTIFICATION
, then the implementation will never deliver notification of reset events, and GetGraphicsResetStatus will always return NO_ERROR.If the behavior is
LOSE_CONTEXT_ON_RESET
, a graphics reset will result in a lost context and require creating a new context as described above. In this case GetGraphicsResetStatus will return an appropriate value from those described above.If a graphics reset notification occurs in a context, a notification must also occur in all other contexts which share objects with that context.
After a graphics reset has occurred on a context, subsequent GL commands on that context (or any context which shares with that context) will generate a
CONTEXT_LOST
error. Such commands will not have side effects (in particular, they will not modify memory passed by pointer for query results, and may not block indefinitely or cause termination of the application. Exceptions to this behavior include:GetError
and GetGraphicsResetStatus behave normally following a graphics reset, so that the application can determine a reset has occurred, and when it is safe to destroy and recreate the context.- Any commands which might cause a polling application to block indefinitely will generate a CONTEXT_LOST error, but will also return a value indicating completion to the application.
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nglReadnPixels
public static void nglReadnPixels(int x, int y, int width, int height, int format, int type, int bufSize, long pixels) Unsafe version of:ReadnPixels
- Parameters:
bufSize
- the maximum number of bytes to write intodata
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, int bufSize, long pixels) - Parameters:
x
- the left pixel coordinatey
- the lower pixel coordinatewidth
- the number of pixels to read in the x-dimensionheight
- the number of pixels to read in the y-dimensionformat
- the pixel format. One of:type
- the pixel type. One of:bufSize
- the maximum number of bytes to write intodata
pixels
- a buffer in which to place the returned pixel data
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, ByteBuffer pixels) - Parameters:
x
- the left pixel coordinatey
- the lower pixel coordinatewidth
- the number of pixels to read in the x-dimensionheight
- the number of pixels to read in the y-dimensionformat
- the pixel format. One of:type
- the pixel type. One of:pixels
- a buffer in which to place the returned pixel data
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, ShortBuffer pixels) - Parameters:
x
- the left pixel coordinatey
- the lower pixel coordinatewidth
- the number of pixels to read in the x-dimensionheight
- the number of pixels to read in the y-dimensionformat
- the pixel format. One of:type
- the pixel type. One of:pixels
- a buffer in which to place the returned pixel data
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, IntBuffer pixels) - Parameters:
x
- the left pixel coordinatey
- the lower pixel coordinatewidth
- the number of pixels to read in the x-dimensionheight
- the number of pixels to read in the y-dimensionformat
- the pixel format. One of:type
- the pixel type. One of:pixels
- a buffer in which to place the returned pixel data
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, FloatBuffer pixels) - Parameters:
x
- the left pixel coordinatey
- the lower pixel coordinatewidth
- the number of pixels to read in the x-dimensionheight
- the number of pixels to read in the y-dimensionformat
- the pixel format. One of:type
- the pixel type. One of:pixels
- a buffer in which to place the returned pixel data
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nglGetnUniformfv
public static void nglGetnUniformfv(int program, int location, int bufSize, long params) Unsafe version of:GetnUniformfv
- Parameters:
bufSize
- the maximum number of bytes to write toparams
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glGetnUniformfv
Returns the value or values of a uniform of the default uniform block.- Parameters:
program
- the program objectlocation
- the uniform locationparams
- the buffer in which to place the returned data
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glGetnUniformf
public static float glGetnUniformf(int program, int location) Returns the value or values of a uniform of the default uniform block.- Parameters:
program
- the program objectlocation
- the uniform location
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nglGetnUniformiv
public static void nglGetnUniformiv(int program, int location, int bufSize, long params) Unsafe version of:GetnUniformiv
- Parameters:
bufSize
- the maximum number of bytes to write toparams
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glGetnUniformiv
Integer version ofGetnUniformfv
.- Parameters:
program
- the program objectlocation
- the uniform locationparams
- the buffer in which to place the returned data
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glGetnUniformi
public static int glGetnUniformi(int program, int location) Integer version ofGetnUniformfv
.- Parameters:
program
- the program objectlocation
- the uniform location
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nglGetnUniformuiv
public static void nglGetnUniformuiv(int program, int location, int bufSize, long params) Unsafe version of:GetnUniformuiv
- Parameters:
bufSize
- the maximum number of bytes to write toparams
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glGetnUniformuiv
Unsigned version ofGetnUniformiv
.- Parameters:
program
- the program objectlocation
- the uniform locationparams
- the buffer in which to place the returned data
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glGetnUniformui
public static int glGetnUniformui(int program, int location) Unsigned version ofGetnUniformiv
.- Parameters:
program
- the program objectlocation
- the uniform location
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, short[] pixels) Array version of:ReadnPixels
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, int[] pixels) Array version of:ReadnPixels
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glReadnPixels
public static void glReadnPixels(int x, int y, int width, int height, int format, int type, float[] pixels) Array version of:ReadnPixels
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glGetnUniformfv
public static void glGetnUniformfv(int program, int location, float[] params) Array version of:GetnUniformfv
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glGetnUniformiv
public static void glGetnUniformiv(int program, int location, int[] params) Array version of:GetnUniformiv
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glGetnUniformuiv
public static void glGetnUniformuiv(int program, int location, int[] params) Array version of:GetnUniformuiv
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