WebGL2RenderingContext: copyBufferSubData() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2021.

The WebGL2RenderingContext.copyBufferSubData() method of the WebGL 2 API copies part of the data of a buffer to another buffer.

Syntax

js
copyBufferSubData(readTarget, writeTarget, readOffset, writeOffset, size)

Parameters

readTarget, writeTarget

A GLenum specifying the binding point (target) from whose data store should be read or written. 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.
  • gl.COPY_READ_BUFFER: Buffer for copying from one buffer object to another (provided specifically for copy operations).
  • gl.COPY_WRITE_BUFFER: Buffer for copying from one buffer object to another (provided specifically for copy operations).
  • 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.
readOffset, writeOffset

A GLintptr specifying the byte offset from which to start reading from or writing to the buffer.

size

A GLsizei in bytes specifying the size of the data to be copied from readTarget to writeTarget.

Return value

None (undefined).

Examples

js
const srcBuffer = gl.createBuffer();
const dstBuffer = gl.createBuffer();

const data = new Float32Array(vertices);
const length = vertices.length * 4;

gl.bindBuffer(gl.ARRAY_BUFFER, srcBuffer);
gl.bufferData(gl.ARRAY_BUFFER, data, gl.STATIC_DRAW);
gl.bindBuffer(gl.COPY_READ_BUFFER, srcBuffer);

gl.bindBuffer(gl.ARRAY_BUFFER, dstBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(length), gl.STATIC_DRAW);

gl.copyBufferSubData(gl.COPY_READ_BUFFER, gl.ARRAY_BUFFER, 0, 0, length);

Specifications

Specification
WebGL 2.0 Specification
# 3.7.3

Browser compatibility

BCD tables only load in the browser

See also