WebGL2RenderingContext.copyBufferSubData

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

See also

• WebGLRenderingContext.bufferData()
• WebGLRenderingContext.bufferSubData()
• WebGLRenderingContext.getBufferParameter()
• WebGL2RenderingContext.getBufferSubData()