WebGLRenderingContext.pixelStorei()

The WebGLRenderingContext.pixelStorei() method of the WebGL API specifies the pixel storage modes.

Syntax

void gl.pixelStorei(pname, param);

Parameters

pname: A GLenum specifying which parameter to set. See below for possible values.
param: A GLint specifying a value to set the pname parameter to. See below for possible values.

Return value

None.

Pixel storage parameters

Parameter name (for `pname`)	Description	Type	Default value	Allowed values (for `param`)	Specified in
`gl.PACK_ALIGNMENT`	Packing of pixel data into memory	`GLint`	4	1, 2, 4, 8	OpenGL ES 2.0
`gl.UNPACK_ALIGNMENT`	Unpacking of pixel data from memory.	`GLint`	4	1, 2, 4, 8	OpenGL ES 2.0
`gl.UNPACK_FLIP_Y_WEBGL`	Flips the source data along its vertical axis if true.	`GLboolean`	false	true, false	WebGL
`gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL`	Multiplies the alpha channel into the other color channels	`GLboolean`	false	true, false	WebGL
`gl.UNPACK_COLORSPACE_CONVERSION_WEBGL`	Default color space conversion or no color space conversion.	`GLenum`	`gl.BROWSER_DEFAULT_WEBGL`	`gl.BROWSER_DEFAULT_WEBGL`, `gl.NONE`	WebGL

When using a WebGL 2 context, the following values are available additionally:

Constant	Description	Type	Allowed values (for `param`)	Specified in
`gl.PACK_ROW_LENGTH`	Number of pixels in a row.	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.PACK_SKIP_PIXELS`	Number of pixel locations skipped before the first pixel is written into memory.	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.PACK_SKIP_ROWS`	Number of rows of pixel locations skipped before the first pixel is written into memory	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.UNPACK_ROW_LENGTH`	Number of pixels in a row.	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.UNPACK_IMAGE_HEIGHT`	Image height used for reading pixel data from memory	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.UNPACK_SKIP_PIXELS`	Number of pixel images skipped before the first pixel is read from memory	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.UNPACK_SKIP_ROWS`	Number of rows of pixel locations skipped before the first pixel is read from memory	`GLint`	0 to `Infinity`	OpenGL ES 3.0
`gl.UNPACK_SKIP_IMAGES`	Number of pixel images skipped before the first pixel is read from memory	`GLint`	0 to `Infinity`	OpenGL ES 3.0

Examples

Setting the pixel storage mode affects the WebGLRenderingContext.readPixels() operations, as well as unpacking of textures with the WebGLRenderingContext.texImage2D() and WebGLRenderingContext.texSubImage2D() methods.

var tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, tex);
gl.pixelStorei(gl.PACK_ALIGNMENT, 4);

To check the values for packing and unpacking of pixel data, you can query the same pixel storage parameters with WebGLRenderingContext.getParameter().

gl.getParameter(gl.PACK_ALIGNMENT);
gl.getParameter(gl.UNPACK_ALIGNMENT);

Specifications

Specification
WebGL Specification (WebGL) # 5.14.3
WebGL Specification (WebGL) # PIXEL_STORAGE_PARAMETERS
WebGL 2.0 Specification (WebGL 2.0) # 3.7.2

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`pixelStorei`	9	12	4	11	12	5.1	≤37	25	Yes	12	8	1.5
`WebGL2`	56	79	51	No	43	No	58	58	51	43	No	7.0