WebGLRenderingContext.bufferSubData()

The WebGLRenderingContext.bufferSubData() method of the WebGL API updates a subset of a buffer object's data store.

Syntax

void gl.bufferSubData(target, offset, data);

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.
offset
A GLintptr specifying an offset in bytes where the data replacement will start.
data Optional
An ArrayBufferSharedArrayBuffer or one of the ArrayBufferView typed array types that will be copied into the data store.

Return value

None.

Exceptions

  • A gl.INVALID_VALUE error is thrown if the data would be written past the end of the buffer or if data is null.
  • A gl.INVALID_ENUM error is thrown if target is not one of the allowed enums.

Examples

Using bufferSubData

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);
gl.bufferSubData(gl.ARRAY_Buffer, 512, data);

Specifications

Specification Status Comment
WebGL 1.0
The definition of 'bufferSubData' in that specification.
Recommendation Initial definition for WebGL.
OpenGL ES 2.0
The definition of 'glBufferSubData' in that specification.
Standard Man page of the OpenGL ES 2 API.
OpenGL ES 3.0
The definition of 'glBufferSubData' in that specification.
Standard Man page of the (similar) OpenGL ES 3 API.

Adds new target buffers:
gl.COPY_READ_BUFFER,
gl.COPY_WRITE_BUFFER,
gl.TRANSFORM_FEEDBACK_BUFFER,
gl.UNIFORM_BUFFER,
gl.PIXEL_PACK_BUFFER,
gl.PIXEL_UNPACK_BUFFER.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support 9 12 4.0 (2.0) 11 12 5.1
WebGL 2 No support [2] No support Nightly build [1] No support No support No support
Feature Android Chrome for Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile
Basic support ? 25 4.0 (2.0) 1.0 ? 12 8.0
WebGL 2 No support No support No support No support No support No support No support

[1] WebGL 2 is enabled by default in Firefox Nightly. To enable it in a release version of Firefox, set the preference webgl.enable-prototype-webgl2 to true in about:config.

[2] To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

See also

Document Tags and Contributors

 Contributors to this page: fscholz
 Last updated by: fscholz,