WebGLRenderingContext: bufferData() method

The WebGLRenderingContext.bufferData() method of the WebGL API initializes and creates the buffer object's data store.

Syntax

js-nolint

bufferData(target, size, usage)
bufferData(target, srcData, usage)

Parameters

target
- : A {{domxref("WebGL_API/Types", "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.
  When using a {{domxref("WebGL2RenderingContext", "WebGL 2 context", "", 1)}}, the following values are available additionally:
  - 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.
size
- : A {{domxref("WebGL_API/Types", "GLsizeiptr")}} setting the size in bytes of the buffer object's data store.
srcData {{optional_inline}}
- : A {{jsxref("TypedArray")}} or a {{jsxref("DataView")}} that views an {{jsxref("ArrayBuffer")}} or {{jsxref("SharedArrayBuffer")}} that will be copied into the data store. If null, a data store is still created, but the content is uninitialized and undefined.
usage
- : A {{domxref("WebGL_API/Types", "GLenum")}} specifying the intended usage pattern of the data store for optimization purposes. Possible values:
  - gl.STATIC_DRAW
    - : The contents are intended to be specified once by the application, and used many times as the source for WebGL drawing and image specification commands.
  - gl.DYNAMIC_DRAW
    - : The contents are intended to be respecified repeatedly by the application, and used many times as the source for WebGL drawing and image specification commands.
  - gl.STREAM_DRAW
    - : The contents are intended to be specified once by the application, and used at most a few times as the source for WebGL drawing and image specification commands.
  When using a {{domxref("WebGL2RenderingContext", "WebGL 2 context", "", 1)}}, the following values are available additionally:
  - gl.STATIC_READ
    - : The contents are intended to be specified once by reading data from WebGL, and queried many times by the application.
  - gl.DYNAMIC_READ
    - : The contents are intended to be respecified repeatedly by reading data from WebGL, and queried many times by the application.
  - gl.STREAM_READ
    - : The contents are intended to be specified once by reading data from WebGL, and queried at most a few times by the application
  - gl.STATIC_COPY
    - : The contents are intended to be specified once by reading data from WebGL, and used many times as the source for WebGL drawing and image specification commands.
  - gl.DYNAMIC_COPY
    - : The contents are intended to be respecified repeatedly by reading data from WebGL, and used many times as the source for WebGL drawing and image specification commands.
  - gl.STREAM_COPY
    - : The contents are intended to be specified once by reading data from WebGL, and used at most a few times as the source for WebGL drawing and image specification commands.

Return value

None ({{jsxref("undefined")}}).

Exceptions

A gl.OUT_OF_MEMORY error is thrown if the context is unable to create a data store with the given size.
A gl.INVALID_VALUE error is thrown if size is negative.
A gl.INVALID_ENUM error is thrown if target or usage are not one of the allowed enums.

Examples

Using bufferData

const canvas = document.getElementById("canvas");
const gl = canvas.getContext("webgl");
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, 1024, gl.STATIC_DRAW);

Getting buffer information

To check the current buffer usage and buffer size, use the {{domxref("WebGLRenderingContext.getBufferParameter()")}} method.

gl.getBufferParameter(gl.ARRAY_BUFFER, gl.BUFFER_SIZE);
gl.getBufferParameter(gl.ARRAY_BUFFER, gl.BUFFER_USAGE);

Getting size of a typed array

To calculate size parameter for a typed array.

const dataArray = new Float32Array([1, 2, 3, 4]);
const sizeInBytes = dataArray.length * dataArray.BYTES_PER_ELEMENT;