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	Default value	Allowed values (for param)	Specified in
gl.PACK_ROW_LENGTH	Number of pixels in a row.	GLint	0	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	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	0 to Infinity	OpenGL ES 3.0
gl.UNPACK_ROW_LENGTH	Number of pixels in a row.	GLint	0	0 to Infinity	OpenGL ES 3.0
gl.UNPACK_IMAGE_HEIGHT	Image height used for reading pixel data from memory	GLint	0	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	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	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	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

See also

• WebGLRenderingContext.readPixels()
• WebGLRenderingContext.texImage2D()
• WebGLRenderingContext.texSubImage2D()