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docs.GL

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

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 - - - - - - - - - - - ✔
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