import {

LinearEncoding,

REVISION,

RGBAFormat,

sRGBEncoding,

UnsignedByteType

} from "three";

/**

* Determines the texture inline decoding.

*

* @param {Texture} texture - A texture.

* @param {Boolean} isWebGL2 - Whether the context is WebGL 2.

* @return {String} The decoding.

* @ignore

*/

export function getTextureDecoding(texture, isWebGL2) {

let decoding = "texel";

if(texture !== null) {

// Usage of SRGB8_ALPHA8 was introduced in three r133 and disabled temporarily in r135.

const revision = Number.parseInt(REVISION);

// Disable inline decoding for sRGB textures in WebGL 2.

const sRGB8Alpha8 = (

isWebGL2 &&

revision >= 133 && revision !== 135 &&

texture.format === RGBAFormat &&

texture.type === UnsignedByteType &&

texture.encoding === sRGBEncoding

);

if(!sRGB8Alpha8) {

switch(texture.encoding) {

case sRGBEncoding:

decoding = "sRGBToLinear(texel)";

break;

case LinearEncoding:

decoding = "texel";

break;

default:

throw new Error(`Unsupported encoding: ${texture.encoding}`);

}

}

}

return decoding;

}