WEBGL_compressed_texture_astc extension

The WEBGL_compressed_texture_astc extension is part of the WebGL API and exposes Adaptive Scalable Texture Compression (ASTC) compressed texture formats to WebGL.

For more information, see the article Using ASTC Texture Compression for Game Assets by NVIDIA.

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

Note: ASTC compression is typically available on Mali ARM GPUs, Intel GPUs, and NVIDIA Tegra chips.

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

Instance methods

This extension exposes one new methods.

ext.getSupportedProfiles(): Returns an array of strings containing the names of the ASTC profiles supported by the implementation.

Constants

The compressed texture formats are exposed by 28 constants and can be used in two functions: compressedTexImage2D() and compressedTexSubImage2D().

Constants	Blocks	Bits per pixel	`ArrayBuffer` `byteLength`	bytes if height and width are 512
`ext.COMPRESSED_RGBA_ASTC_4x4_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR`	4x4	8.00	`floor((width + 3) / 4) * floor((height + 3) / 4) * 16`	262144
`ext.COMPRESSED_RGBA_ASTC_5x4_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR`	5x4	6.40	`floor((width + 4) / 5) * floor((height + 3) / 4) * 16`	210944
`ext.COMPRESSED_RGBA_ASTC_5x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR`	5x5	5.12	`floor((width + 4) / 5) * floor((height + 4) / 5) * 16`	169744
`ext.COMPRESSED_RGBA_ASTC_6x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR`	6x5	4.27	`floor((width + 5) / 6) * floor((height + 4) / 5) * 16`	141728
`ext.COMPRESSED_RGBA_ASTC_6x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR`	6x6	3.56	`floor((width + 5) / 6) * floor((height + 5) / 6) * 16`	118336
`ext.COMPRESSED_RGBA_ASTC_8x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR`	8x5	3.20	`floor((width + 7) / 8) * floor((height + 4) / 5) * 16`	105472
`ext.COMPRESSED_RGBA_ASTC_8x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR`	8x6	2.67	`floor((width + 7) / 8) * floor((height + 5) / 6) * 16`	88064
`ext.COMPRESSED_RGBA_ASTC_8x8_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR`	8x8	2.00	`floor((width + 7) / 8) * floor((height + 7) / 8) * 16`	65536
`ext.COMPRESSED_RGBA_ASTC_10x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR`	10x5	2.56	`floor((width + 9) / 10) * floor((height + 4) / 5) * 16`	85696
`ext.COMPRESSED_RGBA_ASTC_10x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR`	10x6	2.13	`floor((width + 9) / 10) * floor((height + 5) / 6) * 16`	71552
`ext.COMPRESSED_RGBA_ASTC_10x8_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR`	10x8	1.60	`floor((width + 9) / 10) * floor((height + 7) / 8) * 16`	53248
`ext.COMPRESSED_RGBA_ASTC_10x10_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR`	10x10	1.28	`floor((width + 9) / 10) * floor((height + 9) / 10) * 16`	43264
`ext.COMPRESSED_RGBA_ASTC_12x10_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR`	12x10	1.07	`floor((width + 11) / 12) * floor((height + 9) / 10) * 16`	35776
`ext.COMPRESSED_RGBA_ASTC_12x12_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR`	12x12	0.89	`floor((width + 11) / 12) * floor((height + 11) / 12) * 16`	29584

Examples

const ext = gl.getExtension("WEBGL_compressed_texture_astc");

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

gl.compressedTexImage2D(
  gl.TEXTURE_2D,
  0,
  ext.COMPRESSED_RGBA_ASTC_12x12_KHR,
  512,
  512,
  0,
  textureData,
);

Specifications

Specification
WebGL WEBGL_compressed_texture_astc Extension Specification

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`WEBGL_compressed_texture_astc`	47	79	53	No	34	12	47	47	53	34	12	5.0
`getSupportedProfiles`	47	79	53	No	34	12	47	47	53	34	12	5.0

Docs

Docs4dev

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