WebGLRenderingContext.bufferData()

The WebGLRenderingContext.bufferData() method of the WebGL API initializes and creates the buffer object's data store.

Syntax

// WebGL1:
void gl.bufferData(target, size, usage);
void gl.bufferData(target, ArrayBuffer? srcData, usage);
void gl.bufferData(target, ArrayBufferView srcData, usage);

// WebGL2:
void gl.bufferData(target, ArrayBufferView srcData, usage, srcOffset, length);

Parameters

target

A GLenum specifying the binding point (target). Possible values:

• gl.ARRAY_BUFFER: Buffer containing vertex attributes, such as vertex coordinates, texture coordinate data, or vertex color data.
• gl.ELEMENT_ARRAY_BUFFER: Buffer used for element indices.
• When using a WebGL 2 context, the following values are available additionally:
  • gl.COPY_READ_BUFFER: Buffer for copying from one buffer object to another.
  • gl.COPY_WRITE_BUFFER: Buffer for copying from one buffer object to another.
  • gl.TRANSFORM_FEEDBACK_BUFFER: Buffer for transform feedback operations.
  • gl.UNIFORM_BUFFER: Buffer used for storing uniform blocks.
  • gl.PIXEL_PACK_BUFFER: Buffer used for pixel transfer operations.
  • gl.PIXEL_UNPACK_BUFFER: Buffer used for pixel transfer operations.

size

A GLsizeiptr setting the size in bytes of the buffer object's data store.

srcData Optional

An ArrayBuffer, SharedArrayBuffer or one of the ArrayBufferView typed array types that will be copied into the data store. If null, a data store is still created, but the content is uninitialized and undefined.

usage

A GLenum specifying the intended usage pattern of the data store for optimization purposes. Possible values:

• gl.STATIC_DRAW: The contents are intended to be specified once by the application, and used many times as the source for WebGL drawing and image specification commands.
• gl.DYNAMIC_DRAW: The contents are intended to be respecified repeatedly by the application, and used many times as the source for WebGL drawing and image specification commands.
• gl.STREAM_DRAW: The contents are intended to be specified once by the application, and used at most a few times as the source for WebGL drawing and image specification commands.
• When using a WebGL 2 context, the following values are available additionally:
  • gl.STATIC_READ: The contents are intended to be specified once by reading data from WebGL, and queried many times by the application.
  • gl.DYNAMIC_READ: The contents are intended to be respecified repeatedly by reading data from WebGL, and queried many times by the application.
  • gl.STREAM_READ: The contents are intended to be specified once by reading data from WebGL, and queried at most a few times by the application
  • gl.STATIC_COPY: The contents are intended to be specified once by reading data from WebGL, and used many times as the source for WebGL drawing and image specification commands.
  • gl.DYNAMIC_COPY: The contents are intended to be respecified repeatedly by reading data from WebGL, and used many times as the source for WebGL drawing and image specification commands.
  • gl.STREAM_COPY: The contents are intended to be specified once by reading data from WebGL, and used at most a few times as the source for WebGL drawing and image specification commands.

srcOffset

A GLuint specifying the element index offset where to start reading the buffer.

length Optional

A GLuint defaulting to 0.

Return value

None.

Exceptions

• A gl.OUT_OF_MEMORY error is thrown if the context is unable to create a data store with the given size.
• A gl.INVALID_VALUE error is thrown if size is negative.
• A gl.INVALID_ENUM error is thrown if target or usage are not one of the allowed enums.

Examples

Using bufferData

var canvas = document.getElementById('canvas');
var gl = canvas.getContext('webgl');
var buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, 1024, gl.STATIC_DRAW);

Getting buffer information

To check the current buffer usage and buffer size, use the WebGLRenderingContext.getBufferParameter() method.

gl.getBufferParameter(gl.ARRAY_BUFFER, gl.BUFFER_SIZE);
gl.getBufferParameter(gl.ARRAY_BUFFER, gl.BUFFER_USAGE);

Getting size of a typed array

To calculate size parameter for a typed array.

var dataArray = new Float32Array([1, 2, 3, 4]);
var sizeInBytes = dataArray.length * dataArray.BYTES_PER_ELEMENT;

Specifications

Browser compatibility

See also

• WebGLRenderingContext.createBuffer()
• WebGLRenderingContext.bufferSubData()
• Other buffers: WebGLFramebuffer, WebGLRenderbuffer