2010 Khronos Group
glGetActiveUniformBlockName 3G
glGetActiveUniformBlockName retrieve the name of an active uniform block

## C Specification

void `glGetActiveUniformBlockName` GLuint program GLuint uniformBlockIndex GLsizei bufSize GLsizei *length GLchar *uniformBlockName

## Parameters

program

  Specifies the name of a program containing the uniform block.

uniformBlockIndex

  Specifies the index of the uniform block within program.

bufSize

  Specifies the size of the buffer addressed by uniformBlockName.

length

  Specifies the address of a variable to receive the number of characters that were written to uniformBlockName.

uniformBlockName

  Specifies the address an array of characters to receive the name of the uniform block at uniformBlockIndex.

## Description

`glGetActiveUniformBlockName` retrieves the name of the active uniform block at uniformBlockIndex within program.

program must be the name of a program object for which the command glLinkProgram must have been called in the past, although it is not required that glLinkProgram must have succeeded. The link could have failed because the number of active uniforms exceeded the limit.

uniformBlockIndex is an active uniform block index of program, and must be less than the value of `GL_ACTIVE_UNIFORM_BLOCKS`.

Upon success, the name of the uniform block identified by unifomBlockIndex is returned into uniformBlockName. The name is nul-terminated. The actual number of characters written into uniformBlockName, excluding the nul terminator, is returned in length. If length is `NULL`, no length is returned.

bufSize contains the maximum number of characters (including the nul terminator) that will be written into uniformBlockName.

If an error occurs, nothing will be written to uniformBlockName or length.

## Errors

`GL_INVALID_OPERATION` is generated if program is not the name of a program object for which glLinkProgram has been called in the past.

`GL_INVALID_VALUE` is generated if uniformBlockIndex is greater than or equal to the value of `GL_ACTIVE_UNIFORM_BLOCKS` or is not the index of an active uniform block in program.

## Notes

`glGetActiveUniformBlockName` is available only if the GL version is 3.1 or greater.

## See Also

glGetActiveUniformBlock, glGetUniformBlockIndex

## Copyright

Copyright 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/.