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The WEBGL_compressed_texture_atc extension is part of the WebGL API and exposes 3 ATC compressed texture formats. ATC is a proprietary compression algorithm for compressing textures on handheld devices.
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: ATC compression is typically available on mobile devices with Adreno GPUs, that are currently only built into Qualcomm Snapdragon devices.
This extension is available to both, WebGL1 and WebGL2 contexts.
Constants
The compressed texture formats are exposed by 3 constants and can be used in two functions: compressedTexImage2D() and compressedTexSubImage2D().
ext.COMPRESSED_RGB_ATC_WEBGL- Compresses RGB textures with no alpha channel.
ext.COMPRESSED_RGBA_ATC_EXPLICIT_ALPHA_WEBGL- Compresses RGBA textures using explicit alpha encoding (useful when alpha transitions are sharp).
ext.COMPRESSED_RGBA_ATC_INTERPOLATED_ALPHA_WEBGL- Compresses RGBA textures using interpolated alpha encoding (useful when alpha transitions are gradient).
Examples
var ext = gl.getExtension("WEBGL_compressed_texture_atc");
var texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.compressedTexImage2D(gl.TEXTURE_2D, 0, ext.COMPRESSED_RGB_ATC_WEBGL, 512, 512, 0, textureData);
Specifications
| Specification | Status | Comment |
|---|---|---|
| WEBGL_compressed_texture_atc The definition of 'WEBGL_compressed_texture_atc' in that specification. |
Draft | Initial definition. |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | ? | 18.0 (18.0) | ? | ? | ? |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | ? | ? | ? | ? | ? | ? |