WebGL
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WebGL WEBGL_compressed_texture_astc Extension Specification

Name

WEBGL_compressed_texture_astc

Contact

WebGL working group (public_webgl 'at' khronos.org)

Contributors

Christophe Riccio, Unity

Members of the WebGL working group

Version

Last modified date: December 12, 2016
Revision: 5

Number

WebGL extension #30

Dependencies

Written against the WebGL API 1.0 specification.

Overview

This extension exposes the compressed texture format defined in the KHR_texture_compression_astc_hdr OpenGL ES extension to WebGL. Consult that extension specification for behavioral definitions, including error behaviors.

ASTC textures may be encoded using either high or low dynamic range, corresponding to an "HDR profile" and "LDR profile". The compression format is designed to be extended, and for new profiles to be added in the future. For this reason, enabling the WebGL extension enables all of the profiles supported by the implementation. The supported profiles may be queried by calling getSupportedProfiles against the extension object.

When this extension is enabled:

IDL

[NoInterfaceObject]
interface WEBGL_compressed_texture_astc {
    /* Compressed Texture Format */
    const GLenum COMPRESSED_RGBA_ASTC_4x4_KHR = 0x93B0;
    const GLenum COMPRESSED_RGBA_ASTC_5x4_KHR = 0x93B1;
    const GLenum COMPRESSED_RGBA_ASTC_5x5_KHR = 0x93B2;
    const GLenum COMPRESSED_RGBA_ASTC_6x5_KHR = 0x93B3;
    const GLenum COMPRESSED_RGBA_ASTC_6x6_KHR = 0x93B4;
    const GLenum COMPRESSED_RGBA_ASTC_8x5_KHR = 0x93B5;
    const GLenum COMPRESSED_RGBA_ASTC_8x6_KHR = 0x93B6;
    const GLenum COMPRESSED_RGBA_ASTC_8x8_KHR = 0x93B7;
    const GLenum COMPRESSED_RGBA_ASTC_10x5_KHR = 0x93B8;
    const GLenum COMPRESSED_RGBA_ASTC_10x6_KHR = 0x93B9;
    const GLenum COMPRESSED_RGBA_ASTC_10x8_KHR = 0x93BA;
    const GLenum COMPRESSED_RGBA_ASTC_10x10_KHR = 0x93BB;
    const GLenum COMPRESSED_RGBA_ASTC_12x10_KHR = 0x93BC;
    const GLenum COMPRESSED_RGBA_ASTC_12x12_KHR = 0x93BD;

    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR = 0x93D0;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR = 0x93D1;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR = 0x93D2;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR = 0x93D3;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR = 0x93D4;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR = 0x93D5;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR = 0x93D6;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR = 0x93D7;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR = 0x93D8;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR = 0x93D9;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR = 0x93DA;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR = 0x93DB;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR = 0x93DC;
    const GLenum COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR = 0x93DD;

    // Profile query support.
    sequence<DOMString> getSupportedProfiles();
};
  

New Functions

sequence<DOMString> getSupportedProfiles()
Returns the names of the ASTC profiles supported by the implementation. As of this writing, valid return values will include "ldr", corresponding to the GL_KHR_texture_compression_astc_ldr extension string; and "hdr", corresponding to the GL_KHR_texture_compression_astc_hdr extension string. More profiles may be added in the future.
The intent of the getSupportedProfiles function is to allow easy reconstruction of the underlying OpenGL or OpenGL ES extension strings for environments like Emscripten, by prepending the string GL_KHR_texture_compression_astc_ to the returned profile names.

New Tokens

compressedTexImage2D(GLenum internalformat)
Accepted by the internalformat parameter: COMPRESSED_RGBA_ASTC_4x4_KHR, COMPRESSED_RGBA_ASTC_5x4_KHR, COMPRESSED_RGBA_ASTC_5x5_KHR, COMPRESSED_RGBA_ASTC_6x5_KHR, COMPRESSED_RGBA_ASTC_6x6_KHR, COMPRESSED_RGBA_ASTC_8x5_KHR, COMPRESSED_RGBA_ASTC_8x6_KHR, COMPRESSED_RGBA_ASTC_8x8_KHR, COMPRESSED_RGBA_ASTC_10x5_KHR, COMPRESSED_RGBA_ASTC_10x6_KHR, COMPRESSED_RGBA_ASTC_10x8_KHR, COMPRESSED_RGBA_ASTC_10x10_KHR, COMPRESSED_RGBA_ASTC_12x10_KHR, COMPRESSED_RGBA_ASTC_12x12_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR
compressedTexSubImage2D(GLenum internalformat)
Accepted by the internalformat parameter: COMPRESSED_RGBA_ASTC_4x4_KHR, COMPRESSED_RGBA_ASTC_5x4_KHR, COMPRESSED_RGBA_ASTC_5x5_KHR, COMPRESSED_RGBA_ASTC_6x5_KHR, COMPRESSED_RGBA_ASTC_6x6_KHR, COMPRESSED_RGBA_ASTC_8x5_KHR, COMPRESSED_RGBA_ASTC_8x6_KHR, COMPRESSED_RGBA_ASTC_8x8_KHR, COMPRESSED_RGBA_ASTC_10x5_KHR, COMPRESSED_RGBA_ASTC_10x6_KHR, COMPRESSED_RGBA_ASTC_10x8_KHR, COMPRESSED_RGBA_ASTC_10x10_KHR, COMPRESSED_RGBA_ASTC_12x10_KHR, COMPRESSED_RGBA_ASTC_12x12_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR, COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR

Errors

The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_4x4_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 3) / 4) * floor((height + 3) / 4) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_5x4_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 4) / 5) * floor((height + 3) / 4) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_5x5_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 4) / 5) * floor((height + 4) / 5) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_6x5_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 5) / 6) * floor((height + 4) / 5) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_6x6_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 5) / 6) * floor((height + 5) / 6) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_8x5_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 7) / 8) * floor((height + 4) / 5) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_8x6_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 7) / 8) * floor((height + 5) / 6) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_8x8_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 7) / 8) * floor((height + 7) / 8) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_10x5_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 9) / 10) * floor((height + 4) / 5) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_10x6_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 9) / 10) * floor((height + 5) / 6) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_10x8_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 9) / 10) * floor((height + 7) / 8) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_10x10_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 9) / 10) * floor((height + 9) / 10) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_12x10_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 11) / 12) * floor((height + 9) / 10) * 16
The error INVALID_VALUE is generated by compressedTexImage2D and compressedTexSubImage2D if the internalformat parameter is COMPRESSED_RGBA_ASTC_12x12_KHR or COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR and the byteLength of the ArrayBufferView is not:
floor((width + 11) / 12) * floor((height + 11) / 12) * 16

Revision History

Revision 1, 2015/03/10

Revision 2, 2015/08/07

Revision 3, 2015/08/10

Revision 4, 2015/08/10

Revision 5, 2016/12/12