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    WebGL2RenderingContext.copyBufferSubData()

    This is an experimental technology
    Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

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

    Syntax

    void gl.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.

    Examples

    var srcBuffer = gl.createBuffer();
var dstBuffer = gl.createBuffer();

var data = new Float32Array(vertices);
var 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 Status Comment
    WebGL 2.0
    The definition of 'copyBufferSubData' in that specification.    		 Editor's Draft Initial definition for WebGL.
    OpenGL ES 3.0
    The definition of 'glCopyBufferSubData' in that specification.    		 Standard Man page of the (similar) OpenGL API.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support No support [2] Nightly build [1] No support No support No support
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support No support No support No support No support No support No support

    [1] WebGL 2 is enabled by default in Firefox Nightly. To enable it in a release version of Firefox, set the preference webgl.enable-prototype-webgl2 to true in about:config.

    [2] To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

    See also

    Document Tags and Contributors

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     Contributors to this page: fscholz
     Last updated by: fscholz,