app/node_modules/@babylonjs/core/Misc/khronosTextureContainer.js

/* eslint-disable @typescript-eslint/naming-convention */
import { Logger } from "../Misc/logger.js";
/**
 * for description see https://www.khronos.org/opengles/sdk/tools/KTX/
 * for file layout see https://www.khronos.org/opengles/sdk/tools/KTX/file_format_spec/
 */
export class KhronosTextureContainer {
    /**
     * Creates a new KhronosTextureContainer
     * @param data contents of the KTX container file
     * @param facesExpected should be either 1 or 6, based whether a cube texture or or
     */
    constructor(
    /** contents of the KTX container file */
    data, facesExpected) {
        this.data = data;
        /**
         * If the container has been made invalid (eg. constructor failed to correctly load array buffer)
         */
        this.isInvalid = false;
        if (!KhronosTextureContainer.IsValid(data)) {
            this.isInvalid = true;
            Logger.Error("texture missing KTX identifier");
            return;
        }
        // load the reset of the header in native 32 bit uint
        const dataSize = Uint32Array.BYTES_PER_ELEMENT;
        const headerDataView = new DataView(this.data.buffer, this.data.byteOffset + 12, 13 * dataSize);
        const endianness = headerDataView.getUint32(0, true);
        const littleEndian = endianness === 0x04030201;
        this.glType = headerDataView.getUint32(1 * dataSize, littleEndian); // must be 0 for compressed textures
        this.glTypeSize = headerDataView.getUint32(2 * dataSize, littleEndian); // must be 1 for compressed textures
        this.glFormat = headerDataView.getUint32(3 * dataSize, littleEndian); // must be 0 for compressed textures
        this.glInternalFormat = headerDataView.getUint32(4 * dataSize, littleEndian); // the value of arg passed to gl.compressedTexImage2D(,,x,,,,)
        this.glBaseInternalFormat = headerDataView.getUint32(5 * dataSize, littleEndian); // specify GL_RGB, GL_RGBA, GL_ALPHA, etc (un-compressed only)
        this.pixelWidth = headerDataView.getUint32(6 * dataSize, littleEndian); // level 0 value of arg passed to gl.compressedTexImage2D(,,,x,,,)
        this.pixelHeight = headerDataView.getUint32(7 * dataSize, littleEndian); // level 0 value of arg passed to gl.compressedTexImage2D(,,,,x,,)
        this.pixelDepth = headerDataView.getUint32(8 * dataSize, littleEndian); // level 0 value of arg passed to gl.compressedTexImage3D(,,,,,x,,)
        this.numberOfArrayElements = headerDataView.getUint32(9 * dataSize, littleEndian); // used for texture arrays
        this.numberOfFaces = headerDataView.getUint32(10 * dataSize, littleEndian); // used for cubemap textures, should either be 1 or 6
        this.numberOfMipmapLevels = headerDataView.getUint32(11 * dataSize, littleEndian); // number of levels; disregard possibility of 0 for compressed textures
        this.bytesOfKeyValueData = headerDataView.getUint32(12 * dataSize, littleEndian); // the amount of space after the header for meta-data
        // Make sure we have a compressed type.  Not only reduces work, but probably better to let dev know they are not compressing.
        if (this.glType !== 0) {
            Logger.Error("only compressed formats currently supported");
            this.isInvalid = true;
            return;
        }
        else {
            // value of zero is an indication to generate mipmaps @ runtime.  Not usually allowed for compressed, so disregard.
            this.numberOfMipmapLevels = Math.max(1, this.numberOfMipmapLevels);
        }
        if (this.pixelHeight === 0 || this.pixelDepth !== 0) {
            Logger.Error("only 2D textures currently supported");
            this.isInvalid = true;
            return;
        }
        if (this.numberOfArrayElements !== 0) {
            Logger.Error("texture arrays not currently supported");
            this.isInvalid = true;
            return;
        }
        if (this.numberOfFaces !== facesExpected) {
            Logger.Error("number of faces expected" + facesExpected + ", but found " + this.numberOfFaces);
            this.isInvalid = true;
            return;
        }
        // we now have a completely validated file, so could use existence of loadType as success
        // would need to make this more elaborate & adjust checks above to support more than one load type
        this.loadType = KhronosTextureContainer.COMPRESSED_2D;
    }
    /**
     * Uploads KTX content to a Babylon Texture.
     * It is assumed that the texture has already been created & is currently bound
     * @internal
     */
    uploadLevels(texture, loadMipmaps) {
        switch (this.loadType) {
            case KhronosTextureContainer.COMPRESSED_2D:
                this._upload2DCompressedLevels(texture, loadMipmaps);
                break;
            case KhronosTextureContainer.TEX_2D:
            case KhronosTextureContainer.COMPRESSED_3D:
            case KhronosTextureContainer.TEX_3D:
        }
    }
    _upload2DCompressedLevels(texture, loadMipmaps) {
        // initialize width & height for level 1
        let dataOffset = KhronosTextureContainer.HEADER_LEN + this.bytesOfKeyValueData;
        let width = this.pixelWidth;
        let height = this.pixelHeight;
        const mipmapCount = loadMipmaps ? this.numberOfMipmapLevels : 1;
        for (let level = 0; level < mipmapCount; level++) {
            const imageSize = new Int32Array(this.data.buffer, this.data.byteOffset + dataOffset, 1)[0]; // size per face, since not supporting array cubemaps
            dataOffset += 4; //image data starts from next multiple of 4 offset. Each face refers to same imagesize field above.
            for (let face = 0; face < this.numberOfFaces; face++) {
                const byteArray = new Uint8Array(this.data.buffer, this.data.byteOffset + dataOffset, imageSize);
                const engine = texture.getEngine();
                engine._uploadCompressedDataToTextureDirectly(texture, texture.format, width, height, byteArray, face, level);
                dataOffset += imageSize; // add size of the image for the next face/mipmap
                dataOffset += 3 - ((imageSize + 3) % 4); // add padding for odd sized image
            }
            width = Math.max(1.0, width * 0.5);
            height = Math.max(1.0, height * 0.5);
        }
    }
    /**
     * Checks if the given data starts with a KTX file identifier.
     * @param data the data to check
     * @returns true if the data is a KTX file or false otherwise
     */
    static IsValid(data) {
        if (data.byteLength >= 12) {
            // '«', 'K', 'T', 'X', ' ', '1', '1', '»', '\r', '\n', '\x1A', '\n'
            const identifier = new Uint8Array(data.buffer, data.byteOffset, 12);
            if (identifier[0] === 0xab &&
                identifier[1] === 0x4b &&
                identifier[2] === 0x54 &&
                identifier[3] === 0x58 &&
                identifier[4] === 0x20 &&
                identifier[5] === 0x31 &&
                identifier[6] === 0x31 &&
                identifier[7] === 0xbb &&
                identifier[8] === 0x0d &&
                identifier[9] === 0x0a &&
                identifier[10] === 0x1a &&
                identifier[11] === 0x0a) {
                return true;
            }
        }
        return false;
    }
}
KhronosTextureContainer.HEADER_LEN = 12 + 13 * 4; // identifier + header elements (not including key value meta-data pairs)
// load types
KhronosTextureContainer.COMPRESSED_2D = 0; // uses a gl.compressedTexImage2D()
KhronosTextureContainer.COMPRESSED_3D = 1; // uses a gl.compressedTexImage3D()
KhronosTextureContainer.TEX_2D = 2; // uses a gl.texImage2D()
KhronosTextureContainer.TEX_3D = 3; // uses a gl.texImage3D()
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