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


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


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.


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

Return value

None (undefined).


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);


WebGL 2.0 Specification
# 3.7.3

Browser compatibility

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See also