WebGLRenderingContext.pixelStorei() - Web APIs 编辑
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
BCD tables only load in the browser
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
See also
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