WebGLRenderingContext: pixelStorei() method
The WebGLRenderingContext.pixelStorei() method of the WebGL API specifies the pixel storage modes.
Syntax
js
pixelStorei(pname, param)
Parameters
Return value
None (undefined).
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.
js
const 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().
js
gl.getParameter(gl.PACK_ALIGNMENT);
gl.getParameter(gl.UNPACK_ALIGNMENT);
Specifications
| Specification |
|---|
| WebGL Specification # 5.14.3 |
| WebGL Specification # PIXEL_STORAGE_PARAMETERS |
| WebGL 2.0 Specification # 3.7.2 |
Browser compatibility
BCD tables only load in the browser