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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	Status	Comment
WebGL 1.0 The definition of 'pixelStorei' in that specification.	Recommendation	Initial definition for WebGL.
WebGL 1.0 The definition of 'Pixel Storage Parameters' in that specification.	Recommendation	Additional pixel storage parameters that aren't specified in OpenGL.
OpenGL ES 2.0 The definition of 'glPixelStorei' in that specification.	Standard	Man page of the OpenGL ES 2.0 API.
WebGL 2.0 The definition of 'pixelStorei' in that specification.	Editor's Draft	Updated definition for WebGL 2.
OpenGL ES 3.0 The definition of 'glPixelStorei' in that specification.	Standard	Man page of the OpenGL ES 3.0 API.

Browser compatibility

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	9	12	4	11	12	5.1
`WebGL2`	56	No	51	No	43	No

Feature	Android webview	Chrome for Android	Edge mobile	Firefox for Android	IE mobile	Opera Android	iOS Safari
Basic support	Yes	25	Yes	Yes	11	12	8.1
`WebGL2`	58	58	No	51	No	43	No