WebGL2RenderingContext: getBufferSubData() 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.
* Some parts of this feature may have varying levels of support.
Note: This feature is available in Web Workers.
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
getBufferSubData(target, srcByteOffset, dstData)
getBufferSubData(target, srcByteOffset, dstData, dstOffset)
getBufferSubData(target, srcByteOffset, dstData, dstOffset, length)
Parameters
target-
A
GLenumspecifying 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
GLintptrspecifying the byte offset from which to start reading from the buffer. dstData-
A
TypedArrayor aDataViewobject to copy the data to. IfdstDatais aDataViewthendstOffsetandlengthare interpreted in bytes, otherwisedstData's element type is used. dstOffsetOptional-
A
GLuintspecifying the element index offset to start writing indstData. lengthOptional-
A
GLuintspecifying the number of elements to copy. If this is 0 or not specified,getBufferSubDatawill copy until the end ofdstData.
Return value
None (undefined).
Exceptions
An INVALID_VALUE error is generated if:
offset+returnedData.byteLengthwould extend beyond the end of the bufferreturnedDataisnulloffsetis less than zero.
An INVALID_OPERATION error is generated if:
- zero is bound to
target targetisTRANSFORM_FEEDBACK_BUFFER, and any transform feedback object is currently active.
Examples
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
const arrBuffer = new ArrayBuffer(
vertices.length * Float32Array.BYTES_PER_ELEMENT,
);
gl.getBufferSubData(gl.ARRAY_BUFFER, 0, new Float32Array(arrBuffer));
Specifications
| Specification |
|---|
| WebGL 2.0 Specification # 3.7.3 |
Browser compatibility
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