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# docs.GL

OpenGL 4
OpenGL 3
OpenGL 2
OpenGL ES 3
OpenGL ES 2

# glBufferSubData

## Name

glBufferSubData, glNamedBufferSubData — updates a subset of a buffer object's data store

## C Specification

`void glBufferSubData(` | GLenum target,
| GLintptr offset,
| GLsizeiptr size,
| const GLvoid * data`)`;

`void glNamedBufferSubData(` | GLuint buffer,
| GLintptr offset,
| GLsizei size,
| const void *data`)`;

## Parameters

`target`

  Specifies the target to which the buffer object is bound for `glBufferSubData`, which must be one of the buffer binding targets in the following table:

  Buffer Binding Target | Purpose
  --- | ---
  `GL_ARRAY_BUFFER` | Vertex attributes
  `GL_ATOMIC_COUNTER_BUFFER` | Atomic counter storage
  `GL_COPY_READ_BUFFER` | Buffer copy source
  `GL_COPY_WRITE_BUFFER` | Buffer copy destination
  `GL_DISPATCH_INDIRECT_BUFFER` | Indirect compute dispatch commands
  `GL_DRAW_INDIRECT_BUFFER` | Indirect command arguments
  `GL_ELEMENT_ARRAY_BUFFER` | Vertex array indices
  `GL_PIXEL_PACK_BUFFER` | Pixel read target
  `GL_PIXEL_UNPACK_BUFFER` | Texture data source
  `GL_QUERY_BUFFER` | Query result buffer
  `GL_SHADER_STORAGE_BUFFER` | Read-write storage for shaders
  `GL_TEXTURE_BUFFER` | Texture data buffer
  `GL_TRANSFORM_FEEDBACK_BUFFER` | Transform feedback buffer
  `GL_UNIFORM_BUFFER` | Uniform block storage

`buffer`

  Specifies the name of the buffer object for `glNamedBufferSubData`.

`offset`

  Specifies the offset into the buffer object's data store where data replacement will begin, measured in bytes.

`size`

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

`data`

  Specifies a pointer to the new data that will be copied into the data store.

## Description

`glBufferSubData` and `glNamedBufferSubData` redefine some or all of the data store for the specified buffer object. Data starting at byte offset `offset` and extending for `size` bytes is copied to the data store from the memory pointed to by `data`. `offset` and `size` must define a range lying entirely within the buffer object's data store.

## Notes

When replacing the entire data store, consider using `glBufferSubData` rather than completely recreating the data store with `glBufferData`. This avoids the cost of reallocating the data store.

Consider using multiple buffer objects to avoid stalling the rendering pipeline during data store updates. If any rendering in the pipeline makes reference to data in the buffer object being updated by `glBufferSubData`, especially from the specific region being updated, that rendering must drain from the pipeline before the data store can be updated.

Clients must align data elements consistent with the requirements of the client platform, with an additional base-level requirement that an offset within a buffer to a datum comprising N bytes be a multiple of N.

The `GL_ATOMIC_COUNTER_BUFFER` target is available only if the GL version is 4.2 or greater.

The `GL_DISPATCH_INDIRECT_BUFFER` and `GL_SHADER_STORAGE_BUFFER` targets are available only if the GL version is 4.3 or greater.

The `GL_QUERY_BUFFER` target is available only if the GL version is 4.4 or greater.

## Errors

`GL_INVALID_ENUM` is generated by `glBufferSubData` if `target` is not one of the accepted buffer targets.

`GL_INVALID_OPERATION` is generated by `glBufferSubData` if zero is bound to `target`.

`GL_INVALID_OPERATION` is generated by `glNamedBufferSubData` if `buffer` is not the name of an existing buffer object.

`GL_INVALID_VALUE` is generated if `offset` or `size` is negative, or if $offset + size$ is greater than the value of `GL_BUFFER_SIZE` for the specified buffer object.

`GL_INVALID_OPERATION` is generated if any part of the specified range of the buffer object is mapped with glMapBufferRange or glMapBuffer, unless it was mapped with the `GL_MAP_PERSISTENT_BIT` bit set in the `glMapBufferRange` `access` flags.

`GL_INVALID_OPERATION` is generated if the value of the `GL_BUFFER_IMMUTABLE_STORAGE` flag of the buffer object is `GL_TRUE` and the value of `GL_BUFFER_STORAGE_FLAGS` for the buffer object does not have the `GL_DYNAMIC_STORAGE_BIT` bit set.

## Associated Gets

glGetBufferSubData

## Examples

Load a vertex buffer into OpenGL for later rendering.

    // data_size_in_bytes is the size in bytes of your vertex data.
    // data_vertices is your actual vertex data, probably a huge array of floats

    GLuint vertex_buffer; // Save this for later rendering
    glGenBuffers(1, &vertex_buffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
    glBufferData(GL_ARRAY_BUFFER, data_size_in_bytes, 0, GL_STATIC_DRAW);
    glBufferSubData(GL_ARRAY_BUFFER, 0, data_size_in_bytes, data_vertices);

    GLint size = 0;
    glGetBufferParameteriv(GL_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);
    if(data_size_in_bytes != size)
    {
        glDeleteBuffers(1, &vertex_buffer);
        // Log the error
        return;
    }

    // Success

Load an index buffer into OpenGL for later rendering.

    // data_size_in_bytes is the size in bytes of your vertex data.
    // data_indices is an array of integer offsets into your vertex data.

    GLuint index_buffer; // Save this for later rendering
    glGenBuffers(1, &index_buffer);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, data_size_in_bytes, 0, GL_STATIC_DRAW);
    glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, data_size_in_bytes, data_indices);

    GLint size = 0;
    glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);
    if(data_size_in_bytes != size)
    {
        glDeleteBuffers(1, &index_buffer);
        // Log the error
        return;
    }

    // Success

## Tutorials

opengl-tutorial.org - Particles / Instancing

## Version Support

| 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
`glBufferSubData` | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔
`glNamedBufferSubData` | - | - | - | - | - | - | - | - | - | - | - | ✔

## See Also

glBindBuffer, glBufferData, glMapBuffer, glMapBufferRange, glUnmapBuffer

## Copyright

Copyright © 2005 Addison-Wesley. 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/.

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