The WEBGL_compressed_texture_es3 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.
Availability: This extension is only available to WebGL1 contexts. In WebGL2, the functionality of this extension is available on the WebGL2 context by default.
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_es3");
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_es3 The definition of 'WEBGL_compressed_texture_es3' in that specification. |
Draft | Initial definition. |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | No support | 46.0 (46.0) [1] | No support | No support | No support |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | No support | No support | ? | No support | No support | No support |
[1] Toggling the webgl.enable-draft-extensions preference in about:config is required.