WEBGL_compressed_texture_astc

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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.

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

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

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

var ext = gl.getExtension('WEBGL_compressed_texture_astc');
var 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	Status	Comment
WEBGL_compressed_texture_astc The definition of 'WEBGL_compressed_texture_astc' in that specification.	Recommendation	Initial definition.

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
`getSupportedProfiles`	47	No	53.0	?	?	?

Feature	Android	Chrome for Android	Edge mobile	Firefox for Android	IE mobile	Opera Android	iOS Safari
`getSupportedProfiles`	?	47	No	53.0	?	?	?

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