WebGLRenderingContext: bufferData() method

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

Syntax

js

// WebGL1
bufferData(target, usage)
bufferData(target, size, usage)
bufferData(target, srcData, usage)

// WebGL2
bufferData(target, usage, srcOffset)
bufferData(target, srcData, usage, srcOffset)
bufferData(target, 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, a TypedArray or a DataView 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 (undefined).

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

js

const canvas = document.getElementById("canvas");
const gl = canvas.getContext("webgl");
const 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.

js

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.

js

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

Specifications

Specification
WebGL Specification
# 5.14.5

Browser compatibility

BCD tables only load in the browser

See also