2005 Sams Publishing
glGetBufferSubData 3G
glGetBufferSubData returns a subset of a buffer object's data store

## C Specification

void `glGetBufferSubData` GLenum target GLintptr offset GLsizeiptr size GLvoid * data

## Parameters

target

  Specifies the target buffer object. The symbolic constant must be `GL_ARRAY_BUFFER`, `GL_COPY_READ_BUFFER`, `GL_COPY_WRITE_BUFFER`, `GL_ELEMENT_ARRAY_BUFFER`, `GL_PIXEL_PACK_BUFFER`, `GL_PIXEL_UNPACK_BUFFER`, `GL_TEXTURE_BUFFER`, `GL_TRANSFORM_FEEDBACK_BUFFER`, or `GL_UNIFORM_BUFFER`.

offset

  Specifies the offset into the buffer object's data store from which data will be returned, measured in bytes.

size

  Specifies the size in bytes of the data store region being returned.

data

  Specifies a pointer to the location where buffer object data is returned.

## Description

`glGetBufferSubData` returns some or all of the data from the buffer object currently bound to target. Data starting at byte offset offset and extending for size bytes is copied from the data store to the memory pointed to by data. An error is thrown if the buffer object is currently mapped, or if offset and size together define a range beyond the bounds of the buffer object's data store.

## Notes

If an error is generated, no change is made to the contents of data.

## Errors

`GL_INVALID_ENUM` is generated if target is not `GL_ARRAY_BUFFER`, `GL_ELEMENT_ARRAY_BUFFER`, `GL_PIXEL_PACK_BUFFER`, or `GL_PIXEL_UNPACK_BUFFER`.

`GL_INVALID_VALUE` is generated if offset or size is negative, or if together they define a region of memory that extends beyond the buffer object's allocated data store.

`GL_INVALID_OPERATION` is generated if the reserved buffer object name 0 is bound to target.

`GL_INVALID_OPERATION` is generated if the buffer object being queried is mapped.

## See Also

glBindBuffer, glBufferData, glBufferSubData, glMapBuffer, glUnmapBuffer

## Copyright

Copyright 2005 Addison-Wesley. 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/.