OpenSpace/modules/globebrowsing/chunk/chunkindex.cpp

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2016                                                               *
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#include <modules/globebrowsing/chunk/chunkindex.h>
#include <modules/globebrowsing/geometry/geodetic2.h>

#include <sstream>

namespace {
    const std::string _loggerCat = "ChunkIndex";
}

namespace openspace {

    /**
    Creates the geodetic tile index for the Geodetic patch that covers the
    point p at the specified level
    */
    ChunkIndex::ChunkIndex(const Geodetic2& point, int level)
    : level(level) {
        int numIndicesAtLevel = 1 << level;
        double u = 0.5 + point.lon / (2 * M_PI);
        double v = 0.25 - point.lat / (2 * M_PI);
        double xIndexSpace = u * numIndicesAtLevel;
        double yIndexSpace = v * numIndicesAtLevel;

        x = floor(xIndexSpace);
        y = floor(yIndexSpace);
    }

    ChunkIndex ChunkIndex::child(Quad q) const {
        return ChunkIndex(2 * x + q % 2, 2 * y + q / 2, level + 1);
    }

    ChunkIndex ChunkIndex::parent() const {
        //ghoul_assert(level > 0, "tile at level 0 has no parent!");
        return ChunkIndex(x / 2, y / 2, level - 1);
    }

    ChunkIndex& ChunkIndex::operator--() {
        x /= 2;
        y /= 2;
        level--;
        return *this;
    }

    ChunkIndex ChunkIndex::operator--(int) {
        ChunkIndex tmp(*this);
        --(*this);
        return tmp;
    }

    ChunkIndex& ChunkIndex::operator-=(unsigned int levels) {
        x <<= levels;
        y <<= levels;
        level -= levels;
        return *this;
    }


    /**
    Gets the tile at a specified offset from this tile.
    Accepts delta indices ranging from [-2^level, Infinity[
    */
    ChunkIndex ChunkIndex::getRelatedTile(int deltaX, int deltaY) const {
        int indicesAtThisLevel = 1 << level;
        int newX = (indicesAtThisLevel + x + deltaX) % indicesAtThisLevel;
        int newY = (indicesAtThisLevel + y + deltaY) % indicesAtThisLevel;
        return ChunkIndex(newX, newY, level);
    }

    int ChunkIndex::manhattan(const ChunkIndex& other) const {
        ghoul_assert(level == other.level, "makes no sense if not on same level");
        return std::abs(x - other.x) + std::abs(y - other.y);
    }


    /**
    Creates a hash which can be used as key in hash maps
        BITS | USAGE
         0-6 | level
        6-26 | x
       26-46 | y
       46-64 | reserved for future use, e.g. time key
    */
    ChunkHashKey ChunkIndex::hashKey() const {
        ChunkHashKey key = 0LL;
        key |= level;
        key |= x << 6;
        key |= ((ChunkHashKey)y) << 26;
        return key;
    }


    std::string ChunkIndex::toString() const {
        std::stringstream ss;
        for (int i = level; i > 0; i--){
            char digit = '0';
            int mask = 1 << (i - 1);
            if ((x & mask) != 0) {
                digit++;
            }
            if ((y & mask) != 0) {
                digit++;
                digit++;
            }
            ss << digit;
        }
        return ss.str();
    }

    bool ChunkIndex::operator==(const ChunkIndex& other) const {
        return x == other.x && y == other.y && level == other.level;
    }

    std::ostream& operator<<(std::ostream& os, const ChunkIndex& ci) {
        os << "{ x = " << ci.x << ", y = " << ci.y << ", level = " << ci.level << " }";
        return os;
    }


} // namespace openspace