be_finder.cpp

//
// Created by xhy on 2021/8/23.
//
#include "be_finder.h"
#include <cstdio>
#include <vector>
#include "be_random.h"
#include <cassert>

namespace {
    uint32_t cal_candicate_seed(const Vec2i &p, int salt) {
        return salt - 245998635 * p.z - 1724254968 * p.x;
    }
}

StructureFinder::StructureFinder(const Pos &search_center, size_t range, BEStructureConfig config) {
    //init search center
    //先转成区块坐标
    auto chunk_pos_center = scala_down(search_center, 16);
    //再转成区域坐标
    this->center_ = scala_down(chunk_pos_center, config.spacing);
    this->config_ = config;
    LOG("search center's area position is[%d,%d]", center_.x, center_.z);
    LOG("structure config is:\nSpacing:     [%d]Spawn range:    [%d] Salt:     [%d]", config_.spacing,
        config_.spawnRange,
        config_.salt);

    int area_width = this->config_.spacing * 16;
    LOG("area width is %d", area_width);
    radius_ = static_cast<int>(range) / area_width;
    if (range % config.spacing != 0)
        ++radius_;
    --radius_;
    LOG("serach radius is %d", radius_);
    for (int i = -radius_; i <= radius_; i++) {
        for (int j = -radius_; j <= radius_; j++) {
            Vec2i area_pos = {this->center_.x + i, this->center_.z + j};
            areas_.emplace_back(area_pos, cal_candicate_seed(area_pos, config_.salt));
        }
    }

    auto min_chunk = scala_up(areas_[0].area_pos, this->config_.spacing).min;
    auto max_chunk = scala_up(areas_[areas_.size() - 1].area_pos, config_.spacing).max;
    auto min_pos = scala_up(min_chunk, 16).min;
    auto max_pos = scala_up(max_chunk, 16).max;

    LOG("total %zu areas need search, range is [%d %d] -- [%d %d]", areas_.size(), min_pos.x, min_pos.z,
        max_pos.x, max_pos.z);
}


std::vector<Pos> StructureFinder::get_candicate_positions(uint32_t seed) {
    std::vector<Pos> p;
    for (auto &area: this->areas_) {
        auto pos = get_candicate_pos_in_area(area.area_pos, area.candicate_area_seed + seed);
        p.push_back(pos);
    }
    return p;
}

Pos StructureFinder::get_candicate_pos_in_area(const AreaPos &p, uint32_t area_seed) const {
    assert(config_.num == 2 || config_.num == 4);
    auto box = scala_up(p, config_.spacing);
    uint32_t *mt = mt_n_get(area_seed, config_.num);
    uint32_t r1 = mt[0] % config_.spawnRange;
    uint32_t r2 = mt[1] % config_.spawnRange;
    uint32_t avg_x, avg_z;
    if (config_.num == 2) {
        avg_x = r1;
        avg_z = r2;
    } else {
        uint32_t r3 = mt[2] % config_.spawnRange;
        uint32_t r4 = mt[3] % config_.spawnRange;
        avg_x = static_cast<int>((r1 + r2) / 2);
        avg_z = static_cast<int>((r3 + r4) / 2);
    }
    int i = get_cong_with_module(box.min.x, config_.spacing, avg_x);
    int j = get_cong_with_module(box.min.z, config_.spacing, avg_z);
    return {i, j};
}