vtf-js/dist/core/utils.js

A javascript IO library for the Valve Texture Format.

import { VCompressionMethods, VFlags } from './enums.js';
/** Returns the size of a given mipmap if mipmap 0 is of size `width`,`height` */
export function getMipSize(mipmap, width, height) {
    const div = 2 ** mipmap;
    return [Math.ceil(width / div), Math.ceil(height / div)];
}
/** Returns an estimated header length for the given vtf version and resource count. */
export function getHeaderLength(version, resources = 0) {
    if (version < 2)
        return 63;
    else if (version < 3)
        return 65;
    return 80 + resources * 8;
}
/** Returns the number of faces that should be expected with the given header. */
export function getFaceCount(info) {
    if (!(info.flags & VFlags.Envmap))
        return 1;
    if (info.version < 5 && info.first_frame === -1)
        return 7;
    return 6;
}
/** Returns the first mipmap which does not exceed `target` in width or height. */
export function getThumbMip(width, height, target = 16) {
    const size = Math.max(width, height);
    return Math.ceil(Math.log2(size)) - Math.log2(target);
}
/** Clamps the value `x` between `a` and `b` */
export function clamp(x, a, b) {
    return x <= a ? a : (x >= b ? b : x);
}
/** The % operator in Javascript is for remainders. This does a proper modulo as defined by MDN. */
export function mod(n, d) {
    return ((n % d) + d) % d;
}
/** Rounds the provided integer to the next multiple of 4. */
export function ceil4(x) {
    return ((x + 3) >> 2) * 4;
}
/** Converts 0xAABBCC to 0xCCBBAA. */
export function byteswap3(x) {
    return (x & 0xff) << 16 | (x & 0xff00) | (x & 0xff0000) >> 16;
}
/** Sets the compression/decompression methods used when encoding/decoding Strata-compressed Vtfs. */
export function setCompressionMethod(fn_compress, fn_decompress) {
    compress = fn_compress;
    decompress = fn_decompress;
}
// Use native APIs by default
/** Compresses the specified Uint8Array with the given options and returns the result. */
export let compress = async (data, method, level) => {
    if (level !== -1)
        throw Error('vtf-js: Default compression backend only supports compression level `-1`. Import a `vtf-js/addons/compress/*` module or call `setCompressionMethod` to better support encoding Strata-compressed Vtfs!');
    if (method !== VCompressionMethods.Deflate)
        throw Error(`vtf-js: Default compression backend only supports Deflate compression!`);
    const inStream = new Blob([data]).stream();
    const compStream = new CompressionStream('deflate');
    const outStream = inStream.pipeThrough(compStream);
    const n = new Response(outStream);
    return new Uint8Array(await n.arrayBuffer());
};
/** Decompresses the specified Uint8Array with the given options and returns the result. `level` is not currently used, but is included in the signature for future compatibility. */
export let decompress = async (data, method, _level) => {
    if (method !== VCompressionMethods.Deflate)
        throw Error(`vtf-js: Default decompression backend only supports Deflate decompression!`);
    const inStream = new Blob([data]).stream();
    const decompStream = new DecompressionStream('deflate');
    const outStream = inStream.pipeThrough(decompStream);
    const n = new Response(outStream);
    return new Uint8Array(await n.arrayBuffer());
};