mirror of https://github.com/axmolengine/axmol.git
380 lines
9.7 KiB
C++
380 lines
9.7 KiB
C++
// SPDX-License-Identifier: Apache-2.0
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// ----------------------------------------------------------------------------
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// Copyright 2011-2021 Arm Limited
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy
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// of the License at:
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations
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// under the License.
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// ----------------------------------------------------------------------------
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/**
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* @brief Functions for generating partition tables on demand.
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*/
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#include "astcenc_internal.h"
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/**
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* @brief Generate a canonical representation of a partition pattern.
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*
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* The returned value stores two bits per texel, for up to 6x6x6 texels, where the two bits store
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* the remapped texel index. Remapping ensures that we only match on the partition pattern,
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* independent of the partition order generated by the hash.
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*
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* @param texel_count The number of texels in the block.
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* @param partition_of_texel The partition assignments, in hash order.
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* @param[out] bit_pattern The output bit pattern representation.
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*/
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static void generate_canonical_partitioning(
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int texel_count,
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const uint8_t* partition_of_texel,
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uint64_t bit_pattern[7]
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) {
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// Clear the pattern
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for (int i = 0; i < 7; i++)
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{
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bit_pattern[i] = 0;
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}
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// Store a mapping to reorder the raw partitions so that the the partitions are ordered such
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// that the lowest texel index in partition N is smaller than the lowest texel index in
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// partition N + 1.
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int mapped_index[BLOCK_MAX_PARTITIONS];
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int map_weight_count = 0;
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for (unsigned int i = 0; i < BLOCK_MAX_PARTITIONS; i++)
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{
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mapped_index[i] = -1;
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}
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for (int i = 0; i < texel_count; i++)
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{
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int index = partition_of_texel[i];
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if (mapped_index[index] == -1)
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{
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mapped_index[index] = map_weight_count++;
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}
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uint64_t xlat_index = mapped_index[index];
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bit_pattern[i >> 5] |= xlat_index << (2 * (i & 0x1F));
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}
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}
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/**
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* @brief Compare two canonical patterns to see if they are the same.
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*
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* @param part1 The first canonical bit pattern to check.
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* @param part2 The second canonical bit pattern to check.
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*
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* @return @c true if the patterns are the same, @c false otherwise.
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*/
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static bool compare_canonical_partitionings(
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const uint64_t part1[7],
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const uint64_t part2[7]
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) {
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return (part1[0] == part2[0]) && (part1[1] == part2[1]) &&
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(part1[2] == part2[2]) && (part1[3] == part2[3]) &&
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(part1[4] == part2[4]) && (part1[5] == part2[5]) &&
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(part1[6] == part2[6]);
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}
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/**
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* @brief Compare all partition patterns and remove duplicates.
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*
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* The partitioning algorithm uses a hash function for texel assignment that can produce partitions
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* which have the same texel assignment groupings. It is only useful for the compressor to test one
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* of each, so we mark duplicates as invalid.
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*
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* @param texel_count The first canonical bit pattern to check.
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* @param[in,out] pt The table of partitioning information entries.
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*/
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static void remove_duplicate_partitionings(
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int texel_count,
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partition_info pt[BLOCK_MAX_PARTITIONINGS]
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) {
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uint64_t bit_patterns[BLOCK_MAX_PARTITIONINGS * 7];
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for (unsigned int i = 0; i < BLOCK_MAX_PARTITIONINGS; i++)
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{
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generate_canonical_partitioning(texel_count, pt[i].partition_of_texel, bit_patterns + i * 7);
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for (unsigned int j = 0; j < i; j++)
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{
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if (compare_canonical_partitionings(bit_patterns + 7 * i, bit_patterns + 7 * j))
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{
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pt[i].partition_count = 0;
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break;
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}
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}
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}
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}
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/**
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* @brief Hash function used for procedural partition assignment.
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*
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* @param inp The hash seed.
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*
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* @return The hashed value.
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*/
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static uint32_t hash52(
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uint32_t inp
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) {
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inp ^= inp >> 15;
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// (2^4 + 1) * (2^7 + 1) * (2^17 - 1)
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inp *= 0xEEDE0891;
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inp ^= inp >> 5;
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inp += inp << 16;
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inp ^= inp >> 7;
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inp ^= inp >> 3;
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inp ^= inp << 6;
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inp ^= inp >> 17;
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return inp;
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}
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/**
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* @brief Select texel assignment for a single coordinate.
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*
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* @param seed The seed - the partition index from the block.
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* @param x The texel X coordinate in the block.
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* @param y The texel Y coordinate in the block.
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* @param z The texel Z coordinate in the block.
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* @param partition_count The total partition count of this encoding.
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* @param small_block @c true if the blockhas fewer than 32 texels.
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*
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* @return The assigned partition index for this texel.
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*/
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static int select_partition(
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int seed,
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int x,
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int y,
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int z,
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int partition_count,
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bool small_block
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) {
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// For small blocks bias the coordinates to get better distribution
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if (small_block)
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{
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x <<= 1;
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y <<= 1;
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z <<= 1;
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}
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seed += (partition_count - 1) * 1024;
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uint32_t rnum = hash52(seed);
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uint8_t seed1 = rnum & 0xF;
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uint8_t seed2 = (rnum >> 4) & 0xF;
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uint8_t seed3 = (rnum >> 8) & 0xF;
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uint8_t seed4 = (rnum >> 12) & 0xF;
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uint8_t seed5 = (rnum >> 16) & 0xF;
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uint8_t seed6 = (rnum >> 20) & 0xF;
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uint8_t seed7 = (rnum >> 24) & 0xF;
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uint8_t seed8 = (rnum >> 28) & 0xF;
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uint8_t seed9 = (rnum >> 18) & 0xF;
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uint8_t seed10 = (rnum >> 22) & 0xF;
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uint8_t seed11 = (rnum >> 26) & 0xF;
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uint8_t seed12 = ((rnum >> 30) | (rnum << 2)) & 0xF;
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// Squaring all the seeds in order to bias their distribution towards lower values.
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seed1 *= seed1;
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seed2 *= seed2;
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seed3 *= seed3;
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seed4 *= seed4;
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seed5 *= seed5;
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seed6 *= seed6;
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seed7 *= seed7;
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seed8 *= seed8;
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seed9 *= seed9;
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seed10 *= seed10;
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seed11 *= seed11;
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seed12 *= seed12;
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int sh1, sh2;
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if (seed & 1)
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{
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sh1 = (seed & 2 ? 4 : 5);
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sh2 = (partition_count == 3 ? 6 : 5);
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}
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else
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{
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sh1 = (partition_count == 3 ? 6 : 5);
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sh2 = (seed & 2 ? 4 : 5);
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}
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int sh3 = (seed & 0x10) ? sh1 : sh2;
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seed1 >>= sh1;
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seed2 >>= sh2;
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seed3 >>= sh1;
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seed4 >>= sh2;
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seed5 >>= sh1;
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seed6 >>= sh2;
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seed7 >>= sh1;
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seed8 >>= sh2;
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seed9 >>= sh3;
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seed10 >>= sh3;
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seed11 >>= sh3;
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seed12 >>= sh3;
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int a = seed1 * x + seed2 * y + seed11 * z + (rnum >> 14);
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int b = seed3 * x + seed4 * y + seed12 * z + (rnum >> 10);
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int c = seed5 * x + seed6 * y + seed9 * z + (rnum >> 6);
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int d = seed7 * x + seed8 * y + seed10 * z + (rnum >> 2);
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// Apply the saw
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a &= 0x3F;
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b &= 0x3F;
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c &= 0x3F;
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d &= 0x3F;
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// Remove some of the components if we are to output < 4 partitions.
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if (partition_count <= 3)
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{
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d = 0;
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}
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if (partition_count <= 2)
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{
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c = 0;
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}
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if (partition_count <= 1)
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{
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b = 0;
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}
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int partition;
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if (a >= b && a >= c && a >= d)
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{
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partition = 0;
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}
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else if (b >= c && b >= d)
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{
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partition = 1;
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}
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else if (c >= d)
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{
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partition = 2;
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}
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else
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{
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partition = 3;
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}
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return partition;
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}
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/**
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* @brief Generate a single partition info structure.
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*
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* @param bsd The block size information.
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* @param partition_count The partition count of this partitioning.
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* @param partition_index The partition index / see of this partitioning.
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* @param[out] pi The partition info structure to populate.
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*/
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static void generate_one_partition_info_entry(
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const block_size_descriptor& bsd,
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int partition_count,
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int partition_index,
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partition_info& pi
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) {
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int texels_per_block = bsd.texel_count;
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bool small_block = texels_per_block < 32;
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uint8_t *partition_of_texel = pi.partition_of_texel;
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// Assign texels to partitions
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int texel_idx = 0;
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int counts[BLOCK_MAX_PARTITIONS] { 0 };
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for (unsigned int z = 0; z < bsd.zdim; z++)
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{
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for (unsigned int y = 0; y < bsd.ydim; y++)
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{
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for (unsigned int x = 0; x < bsd.xdim; x++)
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{
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uint8_t part = select_partition(partition_index, x, y, z, partition_count, small_block);
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pi.texels_of_partition[part][counts[part]++] = texel_idx++;
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*partition_of_texel++ = part;
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}
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}
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}
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// Fill loop tail so we can overfetch later
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for (int i = 0; i < partition_count; i++)
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{
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int ptex_count = counts[i];
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int ptex_count_simd = round_up_to_simd_multiple_vla(ptex_count);
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for (int j = ptex_count; j < ptex_count_simd; j++)
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{
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pi.texels_of_partition[i][j] = pi.texels_of_partition[i][ptex_count - 1];
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}
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}
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if (counts[0] == 0)
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{
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pi.partition_count = 0;
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}
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else if (counts[1] == 0)
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{
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pi.partition_count = 1;
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}
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else if (counts[2] == 0)
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{
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pi.partition_count = 2;
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}
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else if (counts[3] == 0)
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{
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pi.partition_count = 3;
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}
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else
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{
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pi.partition_count = 4;
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}
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for (unsigned int i = 0; i < BLOCK_MAX_PARTITIONS; i++)
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{
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pi.partition_texel_count[i] = counts[i];
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pi.coverage_bitmaps[i] = 0ULL;
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}
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unsigned int texels_to_process = astc::min(bsd.texel_count, BLOCK_MAX_KMEANS_TEXELS);
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for (unsigned int i = 0; i < texels_to_process; i++)
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{
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unsigned int idx = bsd.kmeans_texels[i];
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pi.coverage_bitmaps[pi.partition_of_texel[idx]] |= 1ULL << i;
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}
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}
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/* See header for documentation. */
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void init_partition_tables(
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block_size_descriptor& bsd
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) {
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partition_info *par_tab2 = bsd.partitions;
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partition_info *par_tab3 = par_tab2 + BLOCK_MAX_PARTITIONINGS;
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partition_info *par_tab4 = par_tab3 + BLOCK_MAX_PARTITIONINGS;
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partition_info *par_tab1 = par_tab4 + BLOCK_MAX_PARTITIONINGS;
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generate_one_partition_info_entry(bsd, 1, 0, *par_tab1);
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for (int i = 0; i < 1024; i++)
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{
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generate_one_partition_info_entry(bsd, 2, i, par_tab2[i]);
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generate_one_partition_info_entry(bsd, 3, i, par_tab3[i]);
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generate_one_partition_info_entry(bsd, 4, i, par_tab4[i]);
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}
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remove_duplicate_partitionings(bsd.texel_count, par_tab2);
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remove_duplicate_partitionings(bsd.texel_count, par_tab3);
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remove_duplicate_partitionings(bsd.texel_count, par_tab4);
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}
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