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.
This extension exposes one new methods.
ext.getSupportedProfiles()Returns an array of strings containing the names of the ASTC profiles supported by the implementation.
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 byteLengthbytes if height and width are 512 ext.COMPRESSED_RGBA_ASTC_4x4_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR4x4 8.00 floor((width + 3) / 4) * floor((height + 3) / 4) * 16262144 ext.COMPRESSED_RGBA_ASTC_5x4_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR5x4 6.40 floor((width + 4) / 5) * floor((height + 3) / 4) * 16210944 ext.COMPRESSED_RGBA_ASTC_5x5_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR5x5 5.12 floor((width + 4) / 5) * floor((height + 4) / 5) * 16169744 ext.COMPRESSED_RGBA_ASTC_6x5_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR6x5 4.27 floor((width + 5) / 6) * floor((height + 4) / 5) * 16141728 ext.COMPRESSED_RGBA_ASTC_6x6_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR6x6 3.56 floor((width + 5) / 6) * floor((height + 5) / 6) * 16118336 ext.COMPRESSED_RGBA_ASTC_8x5_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR8x5 3.20 floor((width + 7) / 8) * floor((height + 4) / 5) * 16105472 ext.COMPRESSED_RGBA_ASTC_8x6_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR8x6 2.67 floor((width + 7) / 8) * floor((height + 5) / 6) * 1688064 ext.COMPRESSED_RGBA_ASTC_8x8_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR8x8 2.00 floor((width + 7) / 8) * floor((height + 7) / 8) * 1665536 ext.COMPRESSED_RGBA_ASTC_10x5_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR10x5 2.56 floor((width + 9) / 10) * floor((height + 4) / 5) * 1685696 ext.COMPRESSED_RGBA_ASTC_10x6_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR10x6 2.13 floor((width + 9) / 10) * floor((height + 5) / 6) * 1671552 ext.COMPRESSED_RGBA_ASTC_10x8_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR10x8 1.60 floor((width + 9) / 10) * floor((height + 7) / 8) * 1653248 ext.COMPRESSED_RGBA_ASTC_10x10_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR10x10 1.28 floor((width + 9) / 10) * floor((height + 9) / 10) * 1643264 ext.COMPRESSED_RGBA_ASTC_12x10_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR12x10 1.07 floor((width + 11) / 12) * floor((height + 9) / 10) * 1635776 ext.COMPRESSED_RGBA_ASTC_12x12_KHR
ext.COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR12x12 0.89 floor((width + 11) / 12) * floor((height + 11) / 12) * 1629584
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,
);