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The WebGLRenderingContext.pixelStorei() method of the WebGL API specifies the pixel storage modes.
Syntax
void gl.pixelStorei(pname, param);
Parameters
- pname
- A
Glenumspecifying which parameter to set. See below for possible values. - param
- A
GLintspecifying a value to set thepnameparameter 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 (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic support | 9 | 12 | 4.0 (2.0) | 11 | 12 | 5.1 |
| Feature | Android | Chrome for Android | Edge | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|---|---|
| Basic support | ? | 25 | (Yes) | 4.0 (2.0) | 1.0 | ? | 12 | 8.0 |