virtualx-engine/thirdparty/libktx/lib/basis_sgd.h
acazuc a00cf02241 Add support for KTX & KTX2 image format
Add support glTF KHR_texture_basisu extension
2023-08-19 10:27:29 +02:00

85 lines
2.4 KiB
C++

/* -*- tab-width: 4; -*- */
/* vi: set sw=2 ts=4 expandtab textwidth=70: */
/*
* Copyright 2019-2020 The Khronos Group Inc.
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @internal
* @file basisu_sgd.h
* @~English
*
* @brief Declare global data for Basis LZ supercompression with ETC1S.
*
* These functions are private and should not be used outside the library.
*/
#ifndef _BASIS_SGD_H_
#define _BASIS_SGD_H_
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
// This must be the same value as cSliceDescFlagsFrameIsIFrame so we can just
// invert the bit when passing back & forth. As FrameIsIFrame is within
// a C namespace it can't easily be accessed from a c header.
enum bu_image_flags__bits_e { eBUImageIsPframe = 0x02 };
typedef uint32_t buFlags;
typedef struct ktxBasisLzGlobalHeader {
uint16_t endpointCount;
uint16_t selectorCount;
uint32_t endpointsByteLength;
uint32_t selectorsByteLength;
uint32_t tablesByteLength;
uint32_t extendedByteLength;
} ktxBasisLzGlobalHeader;
// This header is followed by imageCount "slice" descriptions.
// 1, or 2 slices per image (i.e. layer, face & slice).
// These offsets are relative to start of a mip level as given by the
// main levelIndex.
typedef struct ktxBasisLzEtc1sImageDesc {
buFlags imageFlags;
uint32_t rgbSliceByteOffset;
uint32_t rgbSliceByteLength;
uint32_t alphaSliceByteOffset;
uint32_t alphaSliceByteLength;
} ktxBasisLzEtc1sImageDesc;
#define BGD_ETC1S_IMAGE_DESCS(bgd) \
reinterpret_cast<ktxBasisLzEtc1sImageDesc*>(bgd + sizeof(ktxBasisLzGlobalHeader))
// The are followed in the global data by these ...
// uint8_t[endpointsByteLength] endpointsData;
// uint8_t[selectorsByteLength] selectorsData;
// uint8_t[tablesByteLength] tablesData;
#define BGD_ENDPOINTS_ADDR(bgd, imageCount) \
(bgd + sizeof(ktxBasisLzGlobalHeader) + sizeof(ktxBasisLzEtc1sImageDesc) * imageCount)
#define BGD_SELECTORS_ADDR(bgd, bgdh, imageCount) (BGD_ENDPOINTS_ADDR(bgd, imageCount) + bgdh.endpointsByteLength)
#define BGD_TABLES_ADDR(bgd, bgdh, imageCount) (BGD_SELECTORS_ADDR(bgd, bgdh, imageCount) + bgdh.selectorsByteLength)
#define BGD_EXTENDED_ADDR(bgd, bgdh, imageCount) (BGD_TABLES_ADDR(bgd, bgdh, imageCount) + bgdh.tablesByteLength)
// Just because this is a convenient place to put it for basis_{en,trans}code.
enum alpha_content_e {
eNone,
eAlpha,
eGreen
};
#ifdef __cplusplus
}
#endif
#endif /* _BASIS_SGD_H_ */