WebGL2RenderingContext.getBufferSubData()

The WebGL2RenderingContext.getBufferSubData() method of the WebGL 2 API reads data from a buffer binding point and writes them to an ArrayBuffer or SharedArrayBuffer.

Syntax

void gl.getBufferSubData(target, srcByteOffset, ArrayBufferView dstData, optional dstOffset, optional 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.
  • 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.
srcByteOffset

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

dstData

An ArrayBufferView to copy the data to. If dstData is a DataView then dstOffset and length are interpreted in bytes, otherwise dstData's element type is used.

dstOffset Optional

A GLuint specifying the element index offset to start writing in dstData.

length Optional

A GLuint specifying the number of elements to copy. If this is 0 or not specified, getBufferSubData will copy until the end of dstData.

Return value

None.

Exceptions

An INVALID_VALUE error is generated if:

  • offset + returnedData.byteLength would extend beyond the end of the buffer
  • returnedData is null
  • offset is less than zero.

An INVALID_OPERATION error is generated if:

  • zero is bound to target
  • target is TRANSFORM_FEEDBACK_BUFFER, and any transform feedback object is currently active.

Examples

var buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);

var arrBuffer = new ArrayBuffer(vertices.length * Float32Array.BYTES_PER_ELEMENT);
gl.getBufferSubData(gl.ARRAY_BUFFER, 0, new Float32Array(arrBuffer));

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
getBufferSubData
56
79
51
No
43
15
58
58
51
43
15
7.0
SharedArrayBuffer_as_param
60
79
79
No
47
No
60
60
?
44
No
8.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/WebGL2RenderingContext/getBufferSubData