glGetTransformFeedbackiv — query the state of a transform feedback object.
void glGetTransformFeedbackiv(
|
GLuint xfb, |
GLenum pname, | |
GLint *param) ; |
void glGetTransformFeedbacki_v(
|
GLuint xfb, |
GLenum pname, | |
GLuint index, | |
GLint *param) ; |
void glGetTransformFeedbacki64_v(
|
GLuint xfb, |
GLenum pname, | |
GLuint index, | |
GLint64 *param) ; |
xfb
The name of an existing transform feedback object, or zero for the default transform feedback object.
pname
Property to use for the query. Must be one of the values:
GL_TRANSFORM_FEEDBACK_BUFFER_BINDING
,
GL_TRANSFORM_FEEDBACK_BUFFER_START
,
GL_TRANSFORM_FEEDBACK_BUFFER_SIZE
,
GL_TRANSFORM_FEEDBACK_PAUSED
,
GL_TRANSFORM_FEEDBACK_ACTIVE
.
index
Index of the transform feedback stream (for indexed state).
param
The address of a buffer into which will be written the requested state information.
In order to use the Transform Feedback functionality, you need to
configure the Transform Feedback Buffer indexed bindings. This can be
achieved by either using glBindBufferBase
or
glBindBuffersBase
to associate whole buffer object
storage to one of the Transform Feedback Binding Points, or by calling
glBindBufferRange
or
glBindBuffersRange
to use a region of a buffer object
storage for the binding. You may want to (but are not required to) bind a
Transform Feedback Object first, in order to cache the binding
configuration. This usually allows you to restore the Transform Feedback
configuration faster, than if you were to execute a list of API calls
necessary to set up the Transform Feedback state of your liking.
This reference page discusses two types of getters that operate on Transform Feedback Objects and their bindings.
The first class operates on general Transform Feedback binding point
and includes glGetTransformFeedbackiv
function.
glGetTransformFeedbackiv
can be used to retrieve
information about Transform Feedback object bound to the general Transform
Feedback binding point, as configured with a
glBindTransformFeedback
call. In this case, you can
check:
What the ID of the currently bound Transform Feedback Object
is;
(GL_TRANSFORM_FEEDBACK_BUFFER_BINDING
)
Whether the Transform Feedback process is currently paused;
(GL_TRANSFORM_FEEDBACK_PAUSED
)
Whether the Transform Feedback process has been begun and is
currently undergoing;
(GL_TRANSFORM_FEEDBACK_ACTIVE
)
The latter class, which includes
glGetTransformFeedbacki_v
and
glGetTransformFeedbacki64_v
functions, can be used to
check what the current configuration of each of the buffer object regions
bound to Transform Feedback Buffer binding points is. This allows you to
query for the following information:
glGetTransformFeedbacki_v
only: What the
ID of the Buffer Object bound to a Transform Feedback Binding Point
of user-specified index is;
(GL_TRANSFORM_FEEDBACK_BUFFER_BINDING
).
glGetTransformFeedbacki64_v
only: What
the start offset configured for the binding is;
(GL_TRANSFORM_FEEDBACK_BUFFER_START
);
glGetTransformFeedbacki64_v
only: What
the length of the region used for the binding is;
(GL_TRANSFORM_FEEDBACK_BUFFER_SIZE
);
GL_INVALID_OPERATION
error is generated if
xfb
is not zero or the name of an existing
transform feedback object.
GL_INVALID_ENUM
error is generated by
glGetTransformFeedbackiv
if
pname
is not
GL_TRANSFORM_FEEDBACK_PAUSED
or
GL_TRANSFORM_FEEDBACK_ACTIVE
.
GL_INVALID_ENUM
error is generated by
glGetTransformFeedbacki_v
if
pname
is not
GL_TRANSFORM_FEEDBACK_BUFFER_BINDING
.
GL_INVALID_ENUM
error is generated by
glGetTransformFeedbacki64_v
if
pname
is not
GL_TRANSFORM_FEEDBACK_BUFFER_START
or
GL_TRANSFORM_FEEDBACK_BUFFER_SIZE
.
GL_INVALID_VALUE
error is generated by
glGetTransformFeedbacki_v
and
glGetTransformFeedbacki64_v
if
index
is greater than or equal to the number of
binding points for transform feedback (the value of
GL_MAX_TRANSFORM_FEEDBACK_BUFFERS
).
OpenGL Version | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Function / Feature Name | 2.0 | 2.1 | 3.0 | 3.1 | 3.2 | 3.3 | 4.0 | 4.1 | 4.2 | 4.3 | 4.4 | 4.5 |
glGetTransformFeedbackiv
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glGetTransformFeedbacki_v
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glGetTransformFeedbacki64v
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glBindBufferBase, glBindBufferRange, glBindBuffersBase, glBindBuffersRange, glBindTransformFeedback
Copyright © 2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.