OpenSpace/modules/globebrowsing/chunk/chunknode.cpp

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2017                                                               *
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#include <modules/globebrowsing/chunk/chunknode.h>

#include <ghoul/misc/assert.h>

#include <stack>
#include <queue>

namespace openspace::globebrowsing {

ChunkNode::ChunkNode(const Chunk& chunk, ChunkNode* parent)
    : _parent(parent)
    , _children({ {nullptr, nullptr, nullptr, nullptr} })
    , _chunk(chunk)
{}

bool ChunkNode::isRoot() const {
    return _parent == nullptr;
}

bool ChunkNode::isLeaf() const {
    return _children[0] == nullptr;
}

bool ChunkNode::updateChunkTree(const RenderData& data) {
    if (isLeaf()) {
        Chunk::Status status = _chunk.update(data);
        if (status == Chunk::Status::WantSplit) {
            split();
        }
        return status == Chunk::Status::WantMerge;
    }
    else {
        char requestedMergeMask = 0;
        for (int i = 0; i < 4; ++i) {
            if (_children[i]->updateChunkTree(data)) {
                requestedMergeMask |= (1 << i);
            }
        }

        bool allChildrenWantsMerge = requestedMergeMask == 0xf;
        bool thisChunkWantsSplit = _chunk.update(data) == Chunk::Status::WantSplit;

        if (allChildrenWantsMerge && !thisChunkWantsSplit) {
            merge();
        }

        return false;
    }
}

void ChunkNode::depthFirst(const std::function<void(const ChunkNode&)>& f) const {
    f(*this);
    if (!isLeaf()) {
        for (int i = 0; i < 4; ++i) {
            _children[i]->depthFirst(f);
        }
    }
}

void ChunkNode::breadthFirst(const std::function<void(const ChunkNode&)>& f) const {
    std::queue<const ChunkNode*> Q;

    // Loop through nodes in breadths first order
    Q.push(this);
    while (Q.size() > 0) {
        const ChunkNode* node = Q.front();
        Q.pop();

        f(*node);

        // Add children to queue, if any
        if (!node->isLeaf()) {
            for (int i = 0; i < 4; ++i) {
                Q.push(node->_children[i].get());
            }
        }
    }
}

void ChunkNode::reverseBreadthFirst(const std::function<void(const ChunkNode&)>& f) const
{
    std::stack<const ChunkNode*> S;
    std::queue<const ChunkNode*> Q;

    // Loop through nodes in breadths first order
    Q.push(this);
    while (Q.size() > 0) {
        const ChunkNode* node = Q.front(); 
        Q.pop();

        // Add node to future stack
        S.push(node);

        // Add children to queue, if any
        if (!node->isLeaf()) {
            for (const auto& c : node->_children) {
                Q.push(c.get());
            }
            //for (int i = 0; i < 4; ++i) {
            //    Q.push(node->_children[i].get());
            //}
        }
    }

    // Loop through all nodes in stack, this will be reversed breadth first 
    while (S.size() > 0) {
        f(*S.top());
        S.pop();
    }
}

const ChunkNode& ChunkNode::find(const Geodetic2& location) const {
    const ChunkNode* node = this;

    while (!node->isLeaf()) {
        const Geodetic2 center = node->_chunk.surfacePatch().center();
        int index = 0;
        if (center.lon < location.lon) {
            ++index;
        }
        if (location.lat < center.lat) {
            ++index;
            ++index;
        }
        node = &(node->getChild(static_cast<Quad>(index)));
    }
    return *node;
}

const ChunkNode& ChunkNode::getChild(Quad quad) const {
    return *_children[quad];
}

void ChunkNode::split(int depth) {
    if (depth > 0 && isLeaf()) {
        for (size_t i = 0; i < _children.size(); ++i) {
            Chunk chunk(_chunk.owner(), _chunk.tileIndex().child(static_cast<Quad>(i)));
            _children[i] = std::make_unique<ChunkNode>(chunk, this);
        }
    }

    if (depth - 1 > 0) {
        for (size_t i = 0; i < _children.size(); ++i) {
            _children[i]->split(depth - 1);
        }
    }
}

void ChunkNode::merge() {
    for (size_t i = 0; i < _children.size(); ++i) {
        if (_children[i] != nullptr) {
            _children[i]->merge();
        }
        _children[i] = nullptr;
    }
    
    ghoul_assert(isLeaf(), "ChunkNode must be leaf after merge");
}

const Chunk& ChunkNode::getChunk() const {
    return _chunk;
}

} // namespace openspace::globebrowsing