WEBGL_compressed_texture_pvrtc - Web APIs 编辑

The WEBGL_compressed_texture_pvrtc extension is part of the WebGL API and exposes four PVRTC compressed texture formats.

Compressed textures reduce the amount of memory needed to store a texture on the GPU, allowing for higher resolution textures or more of the same resolution textures.

WebGL extensions are available using the WebGLRenderingContext.getExtension() method. For more information, see also Using Extensions in the WebGL tutorial.

Availability: PVRTC is typically only available on mobile devices with PowerVR chipsets. It is used in all generations of the iPhone, iPod Touch and iPad and supported on certain Android devices that use a PowerVR GPU.

This extension is available to both, WebGL1 and WebGL2 contexts.

Note: On iOS devices, this extension is named WEBKIT_WEBGL_compressed_texture_pvrtc.

Constants

The compressed texture formats are exposed by four constants and can be used in two functions: compressedTexImage2D() (where the height and width parameters must be powers of 2) and compressedTexSubImage2D() (where the height and width parameters must equal the current values of the existing texture and the xoffset and yoffset parameters must be 0).

ext.COMPRESSED_RGB_PVRTC_4BPPV1_IMG

RGB compression in 4-bit mode. One block for each 4×4 pixels.

ext.COMPRESSED_RGBA_PVRTC_4BPPV1_IMG

RGBA compression in 4-bit mode. One block for each 4×4 pixels.

ext.COMPRESSED_RGB_PVRTC_2BPPV1_IMG

RGB compression in 2-bit mode. One block for each 8×4 pixels.

ext.COMPRESSED_RGBA_PVRTC_2BPPV1_IMG

RGBA compression in 2-bit mode. One block for each 8×4 pixels.

Examples

var ext = gl.getExtension('WEBGL_compressed_texture_pvrtc');

var texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);

gl.compressedTexImage2D(gl.TEXTURE_2D, 0, ext.COMPRESSED_RGB_PVRTC_4BPPV1_IMG, 512, 512, 0, textureData);

Specifications

Browser compatibility

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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

• PVRTC Texture Compression – Wikipedia
• WebGLRenderingContext.getExtension()
• WebGLRenderingContext.compressedTexImage2D()
• WebGLRenderingContext.compressedTexSubImage2D()
• WebGLRenderingContext.getParameter()