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WEBGL compressed texture etc

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.

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

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

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	?	No	51	?	?	?

Feature	Android webview	Chrome for Android	Edge mobile	Firefox for Android	IE mobile	Opera Android	iOS Safari
Basic support	?	?	No	?	?	?	?

Compatibility notes