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docs.GL

glBufferData

Name

glBufferData — creates and initializes a buffer object's data store

C Specification

void glBufferData(GLenum target,
GLsizeiptr size,
const GLvoid * data,
GLenum usage);

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.

size

Specifies the size in bytes of the buffer object's new data store.

data

Specifies a pointer to data that will be copied into the data store for initialization, or NULL if no data is to be copied.

usage

Specifies the expected usage pattern of the data store. The symbolic constant must be GL_STREAM_DRAW, GL_STREAM_READ, GL_STREAM_COPY, GL_STATIC_DRAW, GL_STATIC_READ, GL_STATIC_COPY, GL_DYNAMIC_DRAW, GL_DYNAMIC_READ, or GL_DYNAMIC_COPY.

Description

glBufferData creates a new data store for the buffer object currently bound to target. Any pre-existing data store is deleted. The new data store is created with the specified size in bytes and usage. If data is not NULL, the data store is initialized with data from this pointer. In its initial state, the new data store is not mapped, it has a NULL mapped pointer, and its mapped access is GL_READ_WRITE.

usage is a hint to the GL implementation as to how a buffer object's data store will be accessed. This enables the GL implementation to make more intelligent decisions that may significantly impact buffer object performance. It does not, however, constrain the actual usage of the data store. usage can be broken down into two parts: first, the frequency of access (modification and usage), and second, the nature of that access. The frequency of access may be one of these:

STREAM

The data store contents will be modified once and used at most a few times.

STATIC

The data store contents will be modified once and used many times.

DYNAMIC

The data store contents will be modified repeatedly and used many times.

The nature of access may be one of these:

DRAW

The data store contents are modified by the application, and used as the source for GL drawing and image specification commands.

READ

The data store contents are modified by reading data from the GL, and used to return that data when queried by the application.

COPY

The data store contents are modified by reading data from the GL, and used as the source for GL drawing and image specification commands.

Notes

If data is NULL, a data store of the specified size is still created, but its contents remain uninitialized and thus undefined.

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.

Errors

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

GL_INVALID_ENUM is generated if usage is not GL_STREAM_DRAW, GL_STREAM_READ, GL_STREAM_COPY, GL_STATIC_DRAW, GL_STATIC_READ, GL_STATIC_COPY, GL_DYNAMIC_DRAW, GL_DYNAMIC_READ, or GL_DYNAMIC_COPY.

GL_INVALID_VALUE is generated if size is negative.

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

GL_OUT_OF_MEMORY is generated if the GL is unable to create a data store with the specified size.

Associated Gets

glGetBufferSubData

glGetBufferParameter with argument GL_BUFFER_SIZE or GL_BUFFER_USAGE

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

See Also

glBindBuffer, glBufferSubData, glMapBuffer, glUnmapBuffer

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