WebGL2RenderingContext: copyBufferSubData() method

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

Syntax

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 (undefined).

Examples

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

const data = new Float32Array(vertices);
const 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

Browser compatibility

See also

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