glTransformFeedbackVaryings — specify values to record in transform feedback buffers
void glTransformFeedbackVaryings(
|
GLuint program, |
GLsizei count, | |
const char **varyings, | |
GLenum bufferMode) ; |
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
.
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
:
Subsequent variables in varyings
will be assigned
to the next buffer binding point.
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
.
glGetTransformFeedbackVarying
is available only if the GL version is 3.0 or greater.
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
.
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
|
- | - | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
glBeginTransformFeedback,
glEndTransformFeedback
,
glGetTransformFeedbackVarying
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. https://opencontent.org/openpub/.