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GLGETTRANSFORMFEEDBA(3G)                         OpenGL 3.3                         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/.



OpenGL 3.3                                       03/08/2011                         GLGETTRANSFORMFEEDBA(3G)