/*
 *
 *  Singe 3
 *  Copyright (C) 2006-2026 Scott Duensing <scott@kangaroopunch.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 */

// Singe - KTX2 textures:  Basis Universal (ETC1S or UASTC) images transcoded at load to the block
// format the GPU has, so one shipped file works everywhere.

#ifndef KTX2_H
#define KTX2_H

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

// What a KTX2 image may be transcoded to, best first.
typedef enum Ktx2FormatE {
	KTX2_RGBA = 0,        // Uncompressed, the fallback
	KTX2_BC7  = 1,        // Desktop GPUs
	KTX2_ASTC = 2,        // ASTC 4x4:  Apple GPUs, the Raspberry Pi 4 and phones
	KTX2_BC3  = 3,        // Older desktop GPUs
	KTX2_ETC2 = 4         // ETC2 with EAC alpha:  the one block format OpenGL ES 3 guarantees (handhelds, the Pi under GLES)
} Ktx2FormatE;

typedef struct Ktx2LevelS {
	uint8_t *data;
	size_t   size;
	int32_t  width;       // Pixels
	int32_t  height;
} Ktx2LevelT;

typedef struct Ktx2ImageS {
	Ktx2FormatE format;
	int32_t     width;
	int32_t     height;
	int32_t     levelCount;
	Ktx2LevelT *levels;   // Largest first
	bool        srgb;     // The file says its colours are sRGB
} Ktx2ImageT;

void ktx2Free(Ktx2ImageT *image);
bool ktx2Is(const void *bytes, size_t size);                                              // Starts with the KTX2 identifier
bool ktx2Transcode(const void *bytes, size_t size, Ktx2FormatE wanted, Ktx2ImageT *out);   // Every level; free with ktx2Free

#endif