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. IfdstData
is aDataView
thendstOffset
andlength
are interpreted in bytes, otherwisedstData
's element type is used. - dstOffset Optional
-
A
GLuint
specifying the element index offset to start writing indstData
. length
Optional-
A
GLuint
specifying the number of elements to copy. If this is 0 or not specified,getBufferSubData
will copy until the end ofdstData
.
Return value
None.
Exceptions
An INVALID_VALUE
error is generated if:
-
offset
+returnedData.byteLength
would extend beyond the end of the buffer returnedData
isnull
offset
is less than zero.
An INVALID_OPERATION
error is generated if:
- zero is bound to
target
-
target
isTRANSFORM_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
Specification |
---|
WebGL 2.0 Specification # 3.7.3 |
Browser compatibility
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