Function ktxCheckHeader2_

lib/checkheader.c:183–299

* @internal * @~English * @brief Check a KTX2 file header. * * As well as checking that the header identifies a KTX 2 file, the function * sanity checks the values and returns information about the texture in a * struct KTX_supplementary_info. * * @param pHeader pointer to the KTX header to check * @param pSuppInfo pointer to a KTX_supplementary_info structure in which to *

 * @author Mark Callow, HI Corporation
 */
KTX_error_code ktxCheckHeader2_(KTX_header2* pHeader,
                                KTX_supplemental_info* pSuppInfo)
{
// supp info is compressed, generateMipmaps and num dimensions. Don't need
// compressed as formatSize gives us that. I think the other 2 aren't needed.
    ktx_uint8_t identifier_reference[12] = KTX2_IDENTIFIER_REF;

    assert(pHeader != NULL && pSuppInfo != NULL);
    ktx_uint32_t max_dim;

    /* Compare identifier, is this a KTX file? */
    if (memcmp(pHeader->identifier, identifier_reference, 12) != 0)
    {
        return KTX_UNKNOWN_FILE_FORMAT;
    }

    /* Check format */
    if (isProhibitedFormat(pHeader->vkFormat))
    {
        return KTX_FILE_DATA_ERROR;
    }
    if (!isValidFormat(pHeader->vkFormat))
    {
        return KTX_UNSUPPORTED_FEATURE;
    }
    if (pHeader->supercompressionScheme == KTX_SS_BASIS_LZ && pHeader->vkFormat != VK_FORMAT_UNDEFINED)
    {
        return KTX_FILE_DATA_ERROR;
    }

    /* Check texture dimensions. KTX files can store 8 types of textures:
       1D, 2D, 3D, cube, and array variants of these. There is currently
       no extension for 3D array textures in any 3D API. */
    if ((pHeader->pixelWidth == 0) ||
        (pHeader->pixelDepth > 0 && pHeader->pixelHeight == 0))
    {
        /* texture must have width */
        /* texture must have height if it has depth */
        return KTX_FILE_DATA_ERROR;
    }

    if (pHeader->pixelDepth > 0)
    {
        if (pHeader->layerCount > 0)
        {
            /* No 3D array textures yet. */
            return KTX_UNSUPPORTED_FEATURE;
        }
        pSuppInfo->textureDimension = 3;
    }
    else if (pHeader->pixelHeight > 0)
    {
        pSuppInfo->textureDimension = 2;
    }
    else
    {
        pSuppInfo->textureDimension = 1;
    }