encoder/basisu_uastc_enc.h

// basisu_uastc_enc.h
// Copyright (C) 2019-2020 Binomial LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#include "basisu_etc.h"

#include "../transcoder/basisu_transcoder_uastc.h"

namespace basisu
{
	const uint32_t TOTAL_PACK_UASTC_LEVELS = 5;

	enum
	{
		// Fastest is the lowest quality, although it's stil substantially higher quality vs. BC1/ETC1. It supports 5 modes.
		// The output may be somewhat blocky because this setting doesn't support 2/3-subset UASTC modes, but it should be less blocky vs. BC1/ETC1.
		// This setting doesn't write BC1 hints, so BC1 transcoding will be slower. 
		// Transcoded ETC1 quality will be lower because it only considers 2 hints out of 32.
		// Avg. 43.45 dB
		cPackUASTCLevelFastest = 0,
		
		// Faster is ~3x slower than fastest. It supports 9 modes.
		// Avg. 46.49 dB
		cPackUASTCLevelFaster = 1,
		
		// Default is ~5.5x slower than fastest. It supports 14 modes.
		// Avg. 47.47 dB
		cPackUASTCLevelDefault = 2,

		// Slower is ~14.5x slower than fastest. It supports all 18 modes.
		// Avg. 48.01 dB
		cPackUASTCLevelSlower = 3,

		// VerySlow is ~200x slower than fastest. 
		// The best quality the codec is capable of, but you'll need to be patient or have a lot of cores.
		// Avg. 48.24 dB
		cPackUASTCLevelVerySlow = 4,

		cPackUASTCLevelMask = 0xF,

		// By default the encoder tries to strike a balance between UASTC and transcoded BC7 quality.
		// These flags allow you to favor only optimizing for lowest UASTC error, or lowest BC7 error.
		cPackUASTCFavorUASTCError = 8,
		cPackUASTCFavorBC7Error = 16,
						
		cPackUASTCETC1FasterHints = 64,
		cPackUASTCETC1FastestHints = 128,
		cPackUASTCETC1DisableFlipAndIndividual = 256,
	};

	// pRGBAPixels: Pointer to source 4x4 block of RGBA pixels (R first in memory).
	// block: Reference to destination UASTC block.
	// level: Controls compression speed vs. performance tradeoff.
	void encode_uastc(const uint8_t* pRGBAPixels, basist::uastc_block& output_block, uint32_t flags = cPackUASTCLevelDefault);

	struct uastc_encode_results
	{
		uint32_t m_uastc_mode;
		uint32_t m_common_pattern;
		basist::astc_block_desc m_astc;
		color_rgba m_solid_color;
		uint64_t m_astc_err;
	};
			  
	void pack_uastc(basist::uastc_block& blk, const uastc_encode_results& result, const etc_block& etc1_blk, uint32_t etc1_bias, const eac_a8_block& etc_eac_a8_blk, bool bc1_hint0, bool bc1_hint1);
	const float UASTC_RDO_DEFAULT_MAX_ALLOWED_RMS_INCREASE_RATIO = 10.0f;
	const float UASTC_RDO_DEFAULT_SKIP_BLOCK_RMS_THRESH = 8.0f;

	struct uastc_rdo_params
	{
		uastc_rdo_params()
		{
			clear();
		}

		void clear()
		{
			m_quality_scaler = 1.0f;
			m_lz_dict_size = 32768;
			m_langrangian_multiplier = 0.025f;
			m_max_allowed_rms_increase_ratio = UASTC_RDO_DEFAULT_MAX_ALLOWED_RMS_INCREASE_RATIO;
			m_skip_block_rms_thresh = UASTC_RDO_DEFAULT_SKIP_BLOCK_RMS_THRESH;
			m_endpoint_refinement = true;
			m_lz_literal_cost = 100;
		}

		// m_quality_scaler: This value controls the overall quality vs. size tradeoff. Smaller values=larger/higher quality, 0=no change, larger values=smaller/lower quality.
		// Good range to try is .2-2.5.
		float m_quality_scaler;

		// m_lz_dict_size: Size of LZ dictionary to simulate in bytes. The larger this value, the slower the encoder but the higher the quality per LZ compressed bit.
		uint32_t m_lz_dict_size;

		// m_langrangian_multiplier: The post-processor tries to reduce rate+distortion*langrangian_mul (rate is approximate LZ bits and distortion is squared error).
		// Larger values push the postprocessor towards optimizing more for lower distortion, and smaller values more for rate.
		float m_langrangian_multiplier;
		
		// m_max_allowed_rms_increase_ratio: How much the RMS error of a block is allowed to increase before a trial is rejected. 1.0=no increase allowed, 1.05=5% increase allowed, etc.
		float m_max_allowed_rms_increase_ratio;
		
		// m_skip_block_rms_thresh: Blocks with this much RMS error or more are completely skipped by the RDO encoder. 
		float m_skip_block_rms_thresh;

		// m_endpoint_refinement: If true, the post-process will attempt to refine the endpoints of blocks with modified selectors. 
		bool m_endpoint_refinement;

		uint32_t m_lz_literal_cost;
	};

	// num_blocks, pBlocks: Number of blocks and pointer to UASTC blocks to process.
	// pBlock_pixels: Pointer to an array of 4x4 blocks containing the original texture pixels. This is NOT a raster image, but a pointer to individual 4x4 blocks.
	// flags: Pass in the same flags used to encode the UASTC blocks. The flags are used to reencode the transcode hints in the same way.
	bool uastc_rdo(uint32_t num_blocks, basist::uastc_block* pBlocks, const color_rgba* pBlock_pixels, const uastc_rdo_params &params, uint32_t flags = cPackUASTCLevelDefault, job_pool* pJob_pool = nullptr, uint32_t total_jobs = 0);
} // namespace basisu