The WEBGL_compressed_texture_etc extension is part of the WebGL API and exposes 10 ETC/EAC 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.
Constants
The compressed texture formats are exposed by 10 constants and can be used in two functions: compressedTexImage2D() and compressedTexSubImage2D().
ext.COMPRESSED_R11_EAC- One-channel (red) unsigned format compression.
ext.COMPRESSED_SIGNED_R11_EAC- One-channel (red) signed format compression.
ext.COMPRESSED_RG11_EAC- Two-channel (red and green) unsigned format compression.
ext.COMPRESSED_SIGNED_RG11_EAC- Two-channel (red and green) signed format compression.
ext.COMPRESSED_RGB8_ETC2- Compresses RGB8 data with no alpha channel.
ext.COMPRESSED_RGBA8_ETC2_EAC- Compresses RGBA8 data. The RGB part is encoded the same as
RGB_ETC2, but the alpha part is encoded separately. ext.COMPRESSED_SRGB8_ETC2- Compresses sRGB8 data with no alpha channel.
ext.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC- Compresses sRGBA8 data. The sRGB part is encoded the same as
SRGB_ETC2, but the alpha part is encoded separately. ext.COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2- Similar to
RGB8_ETC, but with ability to punch through the alpha channel, which means to make it completely opaque or transparent. ext.COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2- Similar to
SRGB8_ETC, but with ability to punch through the alpha channel, which means to make it completely opaque or transparent.
Examples
var ext = gl.getExtension('WEBGL_compressed_texture_etc');
var texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.compressedTexImage2D(gl.TEXTURE_2D, 0, ext.COMPRESSED_RGBA8_ETC2_EAC, 512, 512, 0, textureData);
Specifications
| Specification | Status | Comment |
|---|---|---|
| WEBGL_compressed_texture_etc The definition of 'WEBGL_compressed_texture_etc' in that specification. |
Draft | Initial definition. |
Browser compatibility
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.
| Feature | Chrome | Firefox | Edge | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic Support | ? | 51.0 | (No) | ? | ? | ? |
| Feature | Android | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
|---|---|---|---|---|---|---|---|
| Basic Support | ? | ? | (No) | ? | ? | ? | ? |
Compatibility notes
- This extension was named
WEBGL_compressed_texture_es3from Firefox 46 to Firefox 51 and used to be available on the WebGL 2 context by default – this is not the case anymore. You have to enable it on both, WebGL 1 and WebGL 2 contexts, in order to use it.