52 lines
1.5 KiB
C++
52 lines
1.5 KiB
C++
#include "vf/Streaming.h"
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#include <algorithm>
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namespace vf {
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namespace {
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long long distanceSquared(ColumnCoord a, ColumnCoord b) {
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long long dx = a.x - b.x;
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long long dz = a.z - b.z;
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return dx * dx + dz * dz;
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}
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} // namespace
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std::vector<ColumnCoord> columnsInRadius(ColumnCoord centre, int radius) {
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std::vector<ColumnCoord> columns;
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long long limit = static_cast<long long>(radius) * radius;
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for (int dz = -radius; dz <= radius; ++dz) {
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for (int dx = -radius; dx <= radius; ++dx) {
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ColumnCoord column{centre.x + dx, centre.z + dz};
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if (distanceSquared(column, centre) <= limit) columns.push_back(column);
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}
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}
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std::stable_sort(columns.begin(), columns.end(),
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[&](ColumnCoord lhs, ColumnCoord rhs) {
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return distanceSquared(lhs, centre) < distanceSquared(rhs, centre);
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});
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return columns;
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}
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StreamDelta ChunkStreamer::update(ColumnCoord centre) {
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StreamDelta delta;
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for (ColumnCoord column : columnsInRadius(centre, config.loadRadius)) {
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if (resident.count(column) == 0) delta.load.push_back(column);
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}
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long long unloadLimit = static_cast<long long>(config.unloadRadius) * config.unloadRadius;
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for (ColumnCoord column : resident) {
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if (distanceSquared(column, centre) > unloadLimit) delta.unload.push_back(column);
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}
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for (ColumnCoord column : delta.load) resident.insert(column);
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for (ColumnCoord column : delta.unload) resident.erase(column);
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return delta;
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}
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} // namespace vf
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