GLTRANSFORMFEEDBACKV
Section: [FIXME: manual] (3G)
Updated: 01/26/2021
Page Index
NAME
glTransformFeedbackVaryings - specify values to record in transform feedback buffers
C SPECIFICATION
-
void glTransformFeedbackVaryings(GLuint program, GLsizei count, const char **varyings, GLenum bufferMode);
PARAMETERS
program
-
- The name of the target program object.
count
-
The number of varying variables used for transform feedback.
varyings
-
An array of
count
zero-terminated strings specifying the names of the varying variables to use for transform feedback.
bufferMode
-
Identifies the mode used to capture the varying variables when transform feedback is active.
bufferMode
must be
GL_INTERLEAVED_ATTRIBS
or
GL_SEPARATE_ATTRIBS.
DESCRIPTION
The names of the vertex or geometry shader outputs to be recorded in transform feedback mode are specified using
glTransformFeedbackVaryings. When a geometry shader is active, transform feedback records the values of selected geometry shader output variables from the emitted vertices. Otherwise, the values of the selected vertex shader outputs are recorded.
The state set by
glTranformFeedbackVaryings
is stored and takes effect next time
glLinkProgram()
is called on
program. When
glLinkProgram()
is called,
program
is linked so that the values of the specified varying variables for the vertices of each primitive generated by the GL are written to a single buffer object if
bufferMode
is
GL_INTERLEAVED_ATTRIBS
or multiple buffer objects if
bufferMode
is
GL_SEPARATE_ATTRIBS.
glTransformFeedbackVaryings
can also special identifiers if
bufferMode
is
GL_INTERLEAVED_ATTRIBS:
gl_NextBuffer
-
Subsequent variables in
varyings
will be assigned to the next buffer binding point.
gl_SkipComponents#
-
Where # may be 1, 2, 3, or 4. The variable is treated as having this number of components, but the contents of the memory are preserved under feedback operations.
In addition to the errors generated by
glTransformFeedbackVaryings, the program
program
will fail to link if:
-
•
The count specified by
glTransformFeedbackVaryings
is non-zero, but the program object has no vertex or geometry shader.
-
•
Any variable name specified in the
varyings
array is not declared as an output in the vertex shader (or the geometry shader, if active), or is not one of the special identifiers listed above.
-
•
Special identifiers appear in a
varyings
array where
bufferMode
is not
GL_INTERLEAVED_ATTRIBS.
-
•
Any two entries in the
varyings
array, which are not one of the special varyings above, specify the same varying variable.
-
•
Discounting any special identifiers, the total number of components to capture in any varying variable in
varyings
is greater than the constant
GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS
and the buffer mode is
GL_SEPARATE_ATTRIBS.
-
•
The total number of components to capture is greater than the constant
GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS
and the buffer mode is
GL_INTERLEAVED_ATTRIBS.
NOTES
glGetTransformFeedbackVarying
is available only if the GL version is 3.0 or greater.
ERRORS
GL_INVALID_VALUE
is generated if
program
is not the name of a program object.
GL_INVALID_VALUE
is generated if
bufferMode
is
GL_SEPARATE_ATTRIBS
and
count
is greater than the implementation-dependent limit
GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS.
ASSOCIATED GETS
glGetTransformFeedbackVarying()
VERSION SUPPORT
|
|
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
|
|
glTransformFeedbackVaryings
|
-
|
-
|
✔
|
✔
|
✔
|
✔
|
✔
|
✔
|
✔
|
✔
|
✔
|
✔
|
SEE ALSO
glBeginTransformFeedback(),
glEndTransformFeedback,
glGetTransformFeedbackVarying()
COPYRIGHT
Copyright
©
2010-2014 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.
m[blue]http://opencontent.org/openpub/m[].
COPYRIGHT
Copyright © 2010-2014 Khronos Group