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
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

Feature Chrome Edge Firefox Internet Explorer Opera Safari Servo
Basic Support9124.011125.1No support
WebGL2No support1No support51.0No supportNo supportNo supportNo support
Feature Android Chrome for Android Edge Mobile Firefox for Android IE Mobile Opera Mobile Safari Mobile
Basic Support(Yes)25(Yes)4.0128.1
WebGL2No supportNo support(Yes)51.0No supportNo support

1. To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

See also

Document Tags and Contributors

 Contributors to this page: teoli, player1537, fscholz
 Last updated by: teoli,