glgettransformfeedbackvarying(3g) [centos man page]

GLGETTRANSFORMFEEDBA(3G)					   OpenGL Manual					  GLGETTRANSFORMFEEDBA(3G)

NAME

       glGetTransformFeedbackVarying - retrieve information about varying variables selected for transform feedback

C SPECIFICATION

       void glGetTransformFeedbackVarying(GLuintprogram, GLuintindex, GLsizeibufSize, GLsizei *length, GLsizeisize, GLenum *type, char *name);

PARAMETERS

       program
	   The name of the target program object.

       index
	   The index of the varying variable whose information to retrieve.

       bufSize
	   The maximum number of characters, including the null terminator, that may be written into name.

       length
	   The address of a variable which will receive the number of characters written into name, excluding the null-terminator. If length is
	   NULL no length is returned.

       size
	   The address of a variable that will receive the size of the varying.

       type
	   The address of a variable that will recieve the type of the varying.

       name
	   The address of a buffer into which will be written the name of the varying.

DESCRIPTION

       Information about the set of varying variables in a linked program that will be captured during transform feedback may be retrieved by
       calling glGetTransformFeedbackVarying.  glGetTransformFeedbackVarying provides information about the varying variable selected by index. An
       index of 0 selects the first varying variable specified in the varyings array passed to glTransformFeedbackVaryings(), and an index of
       GL_TRANSFORM_FEEDBACK_VARYINGS-1 selects the last such variable.

       The name of the selected varying is returned as a null-terminated string in name. The actual number of characters written into name,
       excluding the null terminator, is returned in length. If length is NULL, no length is returned. The maximum number of characters that may
       be written into name, including the null terminator, is specified by bufSize.

       The length of the longest varying name in program is given by GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH, which can be queried with
       glGetProgram().

       For the selected varying variable, its type is returned into type. The size of the varying is returned into size. The value in size is in
       units of the type returned in type. The type returned can be any of the scalar, vector, or matrix attribute types returned by
       glGetActiveAttrib(). If an error occurred, the return parameters length, size, type and name will be unmodified. This command will return
       as much information about the varying variables as possible. If no information is available, length will be set to zero and name will be an
       empty string. This situation could arise if glGetTransformFeedbackVarying is called after a failed link.

ERRORS

       GL_INVALID_VALUE is generated if program is not the name of a program object.

       GL_INVALID_VALUE is generated if index is greater or equal to the value of GL_TRANSFORM_FEEDBACK_VARYINGS.

       GL_INVALID_OPERATION is generated program has not been linked.

ASSOCIATED GETS

       glGetProgram() with argument GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH.

SEE ALSO

       glBeginTransformFeedback(), glEndTransformFeedback(), glTransformFeedbackVaryings(), glGetProgram()

COPYRIGHT

       Copyright (C) 2010 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/.

AUTHORS

       opengl.org

opengl.org							    06/10/2014						  GLGETTRANSFORMFEEDBA(3G)

Check Out this Related Man Page

GLTRANSFORMFEEDBACKV(3G)					  [FIXME: manual]					  GLTRANSFORMFEEDBACKV(3G)

NAME

       glTransformFeedbackVaryings - specify values to record in transform feedback buffers

C SPECIFICATION

       void glTransformFeedbackVaryings(GLuintprogram, GLsizeicount, const char **varyings, GLenumbufferMode);

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.

       In addition to the errors generated by glTransformFeedbackVaryings, the program program will fail to link if:

       o   The count specified by glTransformFeedbackVaryings is non-zero, but the program object has no vertex or geometry shader.

       o   Any variable name specified in the varyings array is not declared as an output in the vertex shader (or the geometry shader, if
	   active).

       o   Any two entries in the varyings array specify the same varying variable.

       o   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.

       o   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()

SEE ALSO

       glBeginTransformFeedback(), glEndTransformFeedback(), glGetTransformFeedbackVarying()

COPYRIGHT

       Copyright (C) 2010 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/.

[FIXME: source] 						    05/30/2012						  GLTRANSFORMFEEDBACKV(3G)

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glgettransformfeedbackvarying(3g) [centos man page]

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