godot/thirdparty/astcenc/astcenc_averages_and_directions.cpp

// SPDX-License-Identifier: Apache-2.0
// ----------------------------------------------------------------------------
// Copyright 2011-2023 Arm Limited
//
// 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.
// ----------------------------------------------------------------------------

/**
 * @brief Functions for finding dominant direction of a set of colors.
 */
#if !defined(ASTCENC_DECOMPRESS_ONLY)

#include "astcenc_internal.h"

#include <cassert>

/**
 * @brief Compute the average RGB color of each partition.
 *
 * The algorithm here uses a vectorized sequential scan and per-partition
 * color accumulators, using select() to mask texel lanes in other partitions.
 *
 * We only accumulate sums for N-1 partitions during the scan; the value for
 * the last partition can be computed given that we know the block-wide average
 * already.
 *
 * Because of this we could reduce the loop iteration count so it "just" spans
 * the max texel index needed for the N-1 partitions, which could need fewer
 * iterations than the full block texel count. However, this makes the loop
 * count erratic and causes more branch mispredictions so is a net loss.
 *
 * @param      pi         The partitioning to use.
 * @param      blk        The block data to process.
 * @param[out] averages   The output averages. Unused partition indices will
 *                        not be initialized, and lane<3> will be zero.
 */
static void compute_partition_averages_rgb(
	const partition_info& pi,
	const image_block& blk,
	vfloat4 averages[BLOCK_MAX_PARTITIONS]
) { … }

/**
 * @brief Compute the average RGBA color of each partition.
 *
 * The algorithm here uses a vectorized sequential scan and per-partition
 * color accumulators, using select() to mask texel lanes in other partitions.
 *
 * We only accumulate sums for N-1 partitions during the scan; the value for
 * the last partition can be computed given that we know the block-wide average
 * already.
 *
 * Because of this we could reduce the loop iteration count so it "just" spans
 * the max texel index needed for the N-1 partitions, which could need fewer
 * iterations than the full block texel count. However, this makes the loop
 * count erratic and causes more branch mispredictions so is a net loss.
 *
 * @param      pi         The partitioning to use.
 * @param      blk        The block data to process.
 * @param[out] averages   The output averages. Unused partition indices will
 *                        not be initialized.
 */
static void compute_partition_averages_rgba(
	const partition_info& pi,
	const image_block& blk,
	vfloat4 averages[BLOCK_MAX_PARTITIONS]
) { … }

/* See header for documentation. */
void compute_avgs_and_dirs_4_comp(
	const partition_info& pi,
	const image_block& blk,
	partition_metrics pm[BLOCK_MAX_PARTITIONS]
) { … }

/* See header for documentation. */
void compute_avgs_and_dirs_3_comp(
	const partition_info& pi,
	const image_block& blk,
	unsigned int omitted_component,
	partition_metrics pm[BLOCK_MAX_PARTITIONS]
) { … }

/* See header for documentation. */
void compute_avgs_and_dirs_3_comp_rgb(
	const partition_info& pi,
	const image_block& blk,
	partition_metrics pm[BLOCK_MAX_PARTITIONS]
) { … }

/* See header for documentation. */
void compute_avgs_and_dirs_2_comp(
	const partition_info& pt,
	const image_block& blk,
	unsigned int component1,
	unsigned int component2,
	partition_metrics pm[BLOCK_MAX_PARTITIONS]
) { … }

/* See header for documentation. */
void compute_error_squared_rgba(
	const partition_info& pi,
	const image_block& blk,
	const processed_line4 uncor_plines[BLOCK_MAX_PARTITIONS],
	const processed_line4 samec_plines[BLOCK_MAX_PARTITIONS],
	float line_lengths[BLOCK_MAX_PARTITIONS],
	float& uncor_error,
	float& samec_error
) { … }

/* See header for documentation. */
void compute_error_squared_rgb(
	const partition_info& pi,
	const image_block& blk,
	partition_lines3 plines[BLOCK_MAX_PARTITIONS],
	float& uncor_error,
	float& samec_error
) { … }

#endif