WebGLRenderingContext.bufferData

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

Syntax

// WebGL1: 
void gl.bufferData(target, size, usage); 
void gl.bufferData(target, ArrayBuffer? srcData, usage); 
void gl.bufferData(target, ArrayBufferView srcData, usage); 

// WebGL2: 
void gl.bufferData(target, ArrayBufferView srcData, usage, srcOffset, 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.
• When using a WebGL 2 context, 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 GLsizeiptr setting the size of the buffer object's data store.

srcData Optional

An ArrayBuffer, SharedArrayBuffer or one of the ArrayBufferView typed array types 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 GLenum specifying the usage pattern of the data store. Possible values:

• gl.STATIC_DRAW: Contents of the buffer are likely to be used often and not change often. Contents are written to the buffer, but not read.
• gl.DYNAMIC_DRAW: Contents of the buffer are likely to be used often and change often. Contents are written to the buffer, but not read.
• gl.STREAM_DRAW: Contents of the buffer are likely to not be used often. Contents are written to the buffer, but not read.
• When using a WebGL 2 context, the following values are available additionally:
  • gl.STATIC_READ: Contents of the buffer are likely to be used often and not change often. Contents are read from the buffer, but not written.
  • gl.DYNAMIC_READ: Contents of the buffer are likely to be used often and change often. Contents are read from the buffer, but not written.
  • gl.STREAM_READ: Contents of the buffer are likely to not be used often. Contents are read from the buffer, but not written.
  • gl.STATIC_COPY: Contents of the buffer are likely to be used often and not change often. Contents are neither written or read by the user.
  • gl.DYNAMIC_COPY: Contents of the buffer are likely to be used often and change often. Contents are neither written or read by the user.
  • gl.STREAM_COPY: Contents of the buffer are likely to be used often and not change often. Contents are neither written or read by the user.

srcOffset

A GLuint specifying the element index offset where to start reading the buffer.

length Optional

A GLuint defaulting to 0.

Return value

None.

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

var canvas = document.getElementById('canvas');
var gl = canvas.getContext('webgl');
var 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 WebGLRenderingContext.getBufferParameter() method.

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

Specifications

Browser compatibility

See also

• WebGLRenderingContext.createBuffer()
• WebGLRenderingContext.bufferSubData()
• Other buffers: WebGLFramebuffer, WebGLRenderbuffer